![Andrew Morton](/assets/img/avatar_default.png)
We need the boot CPU's tvec_bases[] entry to be initialised super-early in boot, for early_serial_setup(). That runs within setup_arch(), before even per-cpu areas are initialised. The patch changes tvec_bases to use compile-time initialisation, and adds a separate array `tvec_base_done' to keep track of which CPU has had its tvec_bases[] entry initialised (because we can no longer use the zeroness of that tvec_bases[] entry to determine whether it has been initialised). Thanks to Eugene Surovegin <ebs@ebshome.net> for diagnosing this. Cc: Eugene Surovegin <ebs@ebshome.net> Cc: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1566 lines
41 KiB
C
1566 lines
41 KiB
C
/*
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* linux/kernel/timer.c
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*
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* Kernel internal timers, kernel timekeeping, basic process system calls
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
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*
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* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
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* "A Kernel Model for Precision Timekeeping" by Dave Mills
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* 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
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* serialize accesses to xtime/lost_ticks).
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* Copyright (C) 1998 Andrea Arcangeli
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* 1999-03-10 Improved NTP compatibility by Ulrich Windl
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* 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love
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* 2000-10-05 Implemented scalable SMP per-CPU timer handling.
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* Copyright (C) 2000, 2001, 2002 Ingo Molnar
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* Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
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*/
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#include <linux/kernel_stat.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/notifier.h>
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#include <linux/thread_info.h>
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#include <linux/time.h>
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#include <linux/jiffies.h>
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#include <linux/posix-timers.h>
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#include <linux/cpu.h>
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#include <linux/syscalls.h>
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#include <linux/delay.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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#include <asm/div64.h>
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#include <asm/timex.h>
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#include <asm/io.h>
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#ifdef CONFIG_TIME_INTERPOLATION
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static void time_interpolator_update(long delta_nsec);
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#else
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#define time_interpolator_update(x)
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#endif
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u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
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EXPORT_SYMBOL(jiffies_64);
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/*
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* per-CPU timer vector definitions:
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*/
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#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
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#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
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#define TVN_SIZE (1 << TVN_BITS)
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#define TVR_SIZE (1 << TVR_BITS)
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#define TVN_MASK (TVN_SIZE - 1)
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#define TVR_MASK (TVR_SIZE - 1)
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typedef struct tvec_s {
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struct list_head vec[TVN_SIZE];
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} tvec_t;
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typedef struct tvec_root_s {
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struct list_head vec[TVR_SIZE];
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} tvec_root_t;
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struct tvec_t_base_s {
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spinlock_t lock;
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struct timer_list *running_timer;
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unsigned long timer_jiffies;
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tvec_root_t tv1;
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tvec_t tv2;
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tvec_t tv3;
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tvec_t tv4;
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tvec_t tv5;
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} ____cacheline_aligned_in_smp;
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typedef struct tvec_t_base_s tvec_base_t;
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tvec_base_t boot_tvec_bases;
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EXPORT_SYMBOL(boot_tvec_bases);
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static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = { &boot_tvec_bases };
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static inline void set_running_timer(tvec_base_t *base,
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struct timer_list *timer)
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{
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#ifdef CONFIG_SMP
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base->running_timer = timer;
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#endif
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}
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static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
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{
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unsigned long expires = timer->expires;
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unsigned long idx = expires - base->timer_jiffies;
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struct list_head *vec;
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if (idx < TVR_SIZE) {
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int i = expires & TVR_MASK;
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vec = base->tv1.vec + i;
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} else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
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int i = (expires >> TVR_BITS) & TVN_MASK;
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vec = base->tv2.vec + i;
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} else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
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int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
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vec = base->tv3.vec + i;
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} else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
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int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
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vec = base->tv4.vec + i;
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} else if ((signed long) idx < 0) {
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/*
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* Can happen if you add a timer with expires == jiffies,
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* or you set a timer to go off in the past
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*/
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vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
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} else {
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int i;
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/* If the timeout is larger than 0xffffffff on 64-bit
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* architectures then we use the maximum timeout:
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*/
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if (idx > 0xffffffffUL) {
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idx = 0xffffffffUL;
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expires = idx + base->timer_jiffies;
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}
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i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
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vec = base->tv5.vec + i;
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}
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/*
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* Timers are FIFO:
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*/
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list_add_tail(&timer->entry, vec);
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}
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/***
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* init_timer - initialize a timer.
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* @timer: the timer to be initialized
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*
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* init_timer() must be done to a timer prior calling *any* of the
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* other timer functions.
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*/
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void fastcall init_timer(struct timer_list *timer)
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{
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timer->entry.next = NULL;
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timer->base = per_cpu(tvec_bases, raw_smp_processor_id());
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}
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EXPORT_SYMBOL(init_timer);
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static inline void detach_timer(struct timer_list *timer,
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int clear_pending)
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{
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struct list_head *entry = &timer->entry;
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__list_del(entry->prev, entry->next);
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if (clear_pending)
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entry->next = NULL;
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entry->prev = LIST_POISON2;
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}
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/*
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* We are using hashed locking: holding per_cpu(tvec_bases).lock
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* means that all timers which are tied to this base via timer->base are
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* locked, and the base itself is locked too.
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*
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* So __run_timers/migrate_timers can safely modify all timers which could
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* be found on ->tvX lists.
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*
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* When the timer's base is locked, and the timer removed from list, it is
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* possible to set timer->base = NULL and drop the lock: the timer remains
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* locked.
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*/
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static tvec_base_t *lock_timer_base(struct timer_list *timer,
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unsigned long *flags)
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{
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tvec_base_t *base;
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for (;;) {
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base = timer->base;
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if (likely(base != NULL)) {
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spin_lock_irqsave(&base->lock, *flags);
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if (likely(base == timer->base))
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return base;
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/* The timer has migrated to another CPU */
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spin_unlock_irqrestore(&base->lock, *flags);
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}
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cpu_relax();
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}
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}
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int __mod_timer(struct timer_list *timer, unsigned long expires)
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{
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tvec_base_t *base, *new_base;
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unsigned long flags;
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int ret = 0;
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BUG_ON(!timer->function);
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base = lock_timer_base(timer, &flags);
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if (timer_pending(timer)) {
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detach_timer(timer, 0);
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ret = 1;
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}
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new_base = __get_cpu_var(tvec_bases);
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if (base != new_base) {
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/*
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* We are trying to schedule the timer on the local CPU.
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* However we can't change timer's base while it is running,
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* otherwise del_timer_sync() can't detect that the timer's
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* handler yet has not finished. This also guarantees that
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* the timer is serialized wrt itself.
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*/
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if (likely(base->running_timer != timer)) {
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/* See the comment in lock_timer_base() */
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timer->base = NULL;
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spin_unlock(&base->lock);
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base = new_base;
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spin_lock(&base->lock);
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timer->base = base;
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}
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}
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timer->expires = expires;
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internal_add_timer(base, timer);
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spin_unlock_irqrestore(&base->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL(__mod_timer);
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/***
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* add_timer_on - start a timer on a particular CPU
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* @timer: the timer to be added
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* @cpu: the CPU to start it on
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*
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* This is not very scalable on SMP. Double adds are not possible.
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*/
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void add_timer_on(struct timer_list *timer, int cpu)
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{
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tvec_base_t *base = per_cpu(tvec_bases, cpu);
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unsigned long flags;
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BUG_ON(timer_pending(timer) || !timer->function);
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spin_lock_irqsave(&base->lock, flags);
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timer->base = base;
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internal_add_timer(base, timer);
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spin_unlock_irqrestore(&base->lock, flags);
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}
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/***
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* mod_timer - modify a timer's timeout
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* @timer: the timer to be modified
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*
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* mod_timer is a more efficient way to update the expire field of an
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* active timer (if the timer is inactive it will be activated)
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*
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* mod_timer(timer, expires) is equivalent to:
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*
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* del_timer(timer); timer->expires = expires; add_timer(timer);
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*
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* Note that if there are multiple unserialized concurrent users of the
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* same timer, then mod_timer() is the only safe way to modify the timeout,
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* since add_timer() cannot modify an already running timer.
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*
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* The function returns whether it has modified a pending timer or not.
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* (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
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* active timer returns 1.)
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*/
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int mod_timer(struct timer_list *timer, unsigned long expires)
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{
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BUG_ON(!timer->function);
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/*
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* This is a common optimization triggered by the
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* networking code - if the timer is re-modified
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* to be the same thing then just return:
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*/
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if (timer->expires == expires && timer_pending(timer))
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return 1;
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return __mod_timer(timer, expires);
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}
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EXPORT_SYMBOL(mod_timer);
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/***
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* del_timer - deactive a timer.
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* @timer: the timer to be deactivated
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*
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* del_timer() deactivates a timer - this works on both active and inactive
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* timers.
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*
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* The function returns whether it has deactivated a pending timer or not.
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* (ie. del_timer() of an inactive timer returns 0, del_timer() of an
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* active timer returns 1.)
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*/
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int del_timer(struct timer_list *timer)
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{
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tvec_base_t *base;
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unsigned long flags;
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int ret = 0;
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if (timer_pending(timer)) {
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base = lock_timer_base(timer, &flags);
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if (timer_pending(timer)) {
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detach_timer(timer, 1);
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ret = 1;
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}
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spin_unlock_irqrestore(&base->lock, flags);
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}
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return ret;
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}
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EXPORT_SYMBOL(del_timer);
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#ifdef CONFIG_SMP
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/*
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* This function tries to deactivate a timer. Upon successful (ret >= 0)
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* exit the timer is not queued and the handler is not running on any CPU.
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*
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* It must not be called from interrupt contexts.
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*/
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int try_to_del_timer_sync(struct timer_list *timer)
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{
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tvec_base_t *base;
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unsigned long flags;
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int ret = -1;
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base = lock_timer_base(timer, &flags);
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if (base->running_timer == timer)
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goto out;
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ret = 0;
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if (timer_pending(timer)) {
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detach_timer(timer, 1);
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ret = 1;
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}
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out:
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spin_unlock_irqrestore(&base->lock, flags);
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return ret;
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}
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/***
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* del_timer_sync - deactivate a timer and wait for the handler to finish.
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* @timer: the timer to be deactivated
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*
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* This function only differs from del_timer() on SMP: besides deactivating
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* the timer it also makes sure the handler has finished executing on other
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* CPUs.
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*
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* Synchronization rules: callers must prevent restarting of the timer,
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* otherwise this function is meaningless. It must not be called from
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* interrupt contexts. The caller must not hold locks which would prevent
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* completion of the timer's handler. The timer's handler must not call
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* add_timer_on(). Upon exit the timer is not queued and the handler is
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* not running on any CPU.
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*
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* The function returns whether it has deactivated a pending timer or not.
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*/
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int del_timer_sync(struct timer_list *timer)
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{
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for (;;) {
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int ret = try_to_del_timer_sync(timer);
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if (ret >= 0)
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return ret;
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}
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}
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EXPORT_SYMBOL(del_timer_sync);
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#endif
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static int cascade(tvec_base_t *base, tvec_t *tv, int index)
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{
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/* cascade all the timers from tv up one level */
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struct list_head *head, *curr;
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head = tv->vec + index;
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curr = head->next;
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/*
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* We are removing _all_ timers from the list, so we don't have to
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* detach them individually, just clear the list afterwards.
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*/
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while (curr != head) {
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struct timer_list *tmp;
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tmp = list_entry(curr, struct timer_list, entry);
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BUG_ON(tmp->base != base);
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curr = curr->next;
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internal_add_timer(base, tmp);
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}
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INIT_LIST_HEAD(head);
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return index;
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}
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/***
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* __run_timers - run all expired timers (if any) on this CPU.
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* @base: the timer vector to be processed.
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*
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* This function cascades all vectors and executes all expired timer
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* vectors.
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*/
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#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK
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static inline void __run_timers(tvec_base_t *base)
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{
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struct timer_list *timer;
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spin_lock_irq(&base->lock);
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while (time_after_eq(jiffies, base->timer_jiffies)) {
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struct list_head work_list = LIST_HEAD_INIT(work_list);
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struct list_head *head = &work_list;
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int index = base->timer_jiffies & TVR_MASK;
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/*
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* Cascade timers:
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*/
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if (!index &&
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(!cascade(base, &base->tv2, INDEX(0))) &&
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(!cascade(base, &base->tv3, INDEX(1))) &&
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!cascade(base, &base->tv4, INDEX(2)))
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cascade(base, &base->tv5, INDEX(3));
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++base->timer_jiffies;
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list_splice_init(base->tv1.vec + index, &work_list);
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while (!list_empty(head)) {
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void (*fn)(unsigned long);
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unsigned long data;
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timer = list_entry(head->next,struct timer_list,entry);
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fn = timer->function;
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data = timer->data;
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set_running_timer(base, timer);
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detach_timer(timer, 1);
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spin_unlock_irq(&base->lock);
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{
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int preempt_count = preempt_count();
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fn(data);
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if (preempt_count != preempt_count()) {
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printk(KERN_WARNING "huh, entered %p "
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"with preempt_count %08x, exited"
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" with %08x?\n",
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fn, preempt_count,
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preempt_count());
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BUG();
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}
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}
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spin_lock_irq(&base->lock);
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}
|
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}
|
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set_running_timer(base, NULL);
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spin_unlock_irq(&base->lock);
|
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}
|
|
|
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#ifdef CONFIG_NO_IDLE_HZ
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/*
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* Find out when the next timer event is due to happen. This
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* is used on S/390 to stop all activity when a cpus is idle.
|
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* This functions needs to be called disabled.
|
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*/
|
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unsigned long next_timer_interrupt(void)
|
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{
|
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tvec_base_t *base;
|
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struct list_head *list;
|
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struct timer_list *nte;
|
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unsigned long expires;
|
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unsigned long hr_expires = MAX_JIFFY_OFFSET;
|
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ktime_t hr_delta;
|
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tvec_t *varray[4];
|
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int i, j;
|
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|
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hr_delta = hrtimer_get_next_event();
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if (hr_delta.tv64 != KTIME_MAX) {
|
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struct timespec tsdelta;
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tsdelta = ktime_to_timespec(hr_delta);
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hr_expires = timespec_to_jiffies(&tsdelta);
|
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if (hr_expires < 3)
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return hr_expires + jiffies;
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}
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hr_expires += jiffies;
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|
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base = __get_cpu_var(tvec_bases);
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spin_lock(&base->lock);
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expires = base->timer_jiffies + (LONG_MAX >> 1);
|
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list = NULL;
|
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|
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/* Look for timer events in tv1. */
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j = base->timer_jiffies & TVR_MASK;
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do {
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list_for_each_entry(nte, base->tv1.vec + j, entry) {
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expires = nte->expires;
|
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if (j < (base->timer_jiffies & TVR_MASK))
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list = base->tv2.vec + (INDEX(0));
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goto found;
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}
|
|
j = (j + 1) & TVR_MASK;
|
|
} while (j != (base->timer_jiffies & TVR_MASK));
|
|
|
|
/* Check tv2-tv5. */
|
|
varray[0] = &base->tv2;
|
|
varray[1] = &base->tv3;
|
|
varray[2] = &base->tv4;
|
|
varray[3] = &base->tv5;
|
|
for (i = 0; i < 4; i++) {
|
|
j = INDEX(i);
|
|
do {
|
|
if (list_empty(varray[i]->vec + j)) {
|
|
j = (j + 1) & TVN_MASK;
|
|
continue;
|
|
}
|
|
list_for_each_entry(nte, varray[i]->vec + j, entry)
|
|
if (time_before(nte->expires, expires))
|
|
expires = nte->expires;
|
|
if (j < (INDEX(i)) && i < 3)
|
|
list = varray[i + 1]->vec + (INDEX(i + 1));
|
|
goto found;
|
|
} while (j != (INDEX(i)));
|
|
}
|
|
found:
|
|
if (list) {
|
|
/*
|
|
* The search wrapped. We need to look at the next list
|
|
* from next tv element that would cascade into tv element
|
|
* where we found the timer element.
|
|
*/
|
|
list_for_each_entry(nte, list, entry) {
|
|
if (time_before(nte->expires, expires))
|
|
expires = nte->expires;
|
|
}
|
|
}
|
|
spin_unlock(&base->lock);
|
|
|
|
if (time_before(hr_expires, expires))
|
|
return hr_expires;
|
|
|
|
return expires;
|
|
}
|
|
#endif
|
|
|
|
/******************************************************************/
|
|
|
|
/*
|
|
* Timekeeping variables
|
|
*/
|
|
unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
|
|
unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */
|
|
|
|
/*
|
|
* The current time
|
|
* wall_to_monotonic is what we need to add to xtime (or xtime corrected
|
|
* for sub jiffie times) to get to monotonic time. Monotonic is pegged
|
|
* at zero at system boot time, so wall_to_monotonic will be negative,
|
|
* however, we will ALWAYS keep the tv_nsec part positive so we can use
|
|
* the usual normalization.
|
|
*/
|
|
struct timespec xtime __attribute__ ((aligned (16)));
|
|
struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
|
|
|
|
EXPORT_SYMBOL(xtime);
|
|
|
|
/* Don't completely fail for HZ > 500. */
|
|
int tickadj = 500/HZ ? : 1; /* microsecs */
|
|
|
|
|
|
/*
|
|
* phase-lock loop variables
|
|
*/
|
|
/* TIME_ERROR prevents overwriting the CMOS clock */
|
|
int time_state = TIME_OK; /* clock synchronization status */
|
|
int time_status = STA_UNSYNC; /* clock status bits */
|
|
long time_offset; /* time adjustment (us) */
|
|
long time_constant = 2; /* pll time constant */
|
|
long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */
|
|
long time_precision = 1; /* clock precision (us) */
|
|
long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
|
|
long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
|
|
static long time_phase; /* phase offset (scaled us) */
|
|
long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
|
|
/* frequency offset (scaled ppm)*/
|
|
static long time_adj; /* tick adjust (scaled 1 / HZ) */
|
|
long time_reftime; /* time at last adjustment (s) */
|
|
long time_adjust;
|
|
long time_next_adjust;
|
|
|
|
/*
|
|
* this routine handles the overflow of the microsecond field
|
|
*
|
|
* The tricky bits of code to handle the accurate clock support
|
|
* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
|
|
* They were originally developed for SUN and DEC kernels.
|
|
* All the kudos should go to Dave for this stuff.
|
|
*
|
|
*/
|
|
static void second_overflow(void)
|
|
{
|
|
long ltemp;
|
|
|
|
/* Bump the maxerror field */
|
|
time_maxerror += time_tolerance >> SHIFT_USEC;
|
|
if (time_maxerror > NTP_PHASE_LIMIT) {
|
|
time_maxerror = NTP_PHASE_LIMIT;
|
|
time_status |= STA_UNSYNC;
|
|
}
|
|
|
|
/*
|
|
* Leap second processing. If in leap-insert state at the end of the
|
|
* day, the system clock is set back one second; if in leap-delete
|
|
* state, the system clock is set ahead one second. The microtime()
|
|
* routine or external clock driver will insure that reported time is
|
|
* always monotonic. The ugly divides should be replaced.
|
|
*/
|
|
switch (time_state) {
|
|
case TIME_OK:
|
|
if (time_status & STA_INS)
|
|
time_state = TIME_INS;
|
|
else if (time_status & STA_DEL)
|
|
time_state = TIME_DEL;
|
|
break;
|
|
case TIME_INS:
|
|
if (xtime.tv_sec % 86400 == 0) {
|
|
xtime.tv_sec--;
|
|
wall_to_monotonic.tv_sec++;
|
|
/*
|
|
* The timer interpolator will make time change
|
|
* gradually instead of an immediate jump by one second
|
|
*/
|
|
time_interpolator_update(-NSEC_PER_SEC);
|
|
time_state = TIME_OOP;
|
|
clock_was_set();
|
|
printk(KERN_NOTICE "Clock: inserting leap second "
|
|
"23:59:60 UTC\n");
|
|
}
|
|
break;
|
|
case TIME_DEL:
|
|
if ((xtime.tv_sec + 1) % 86400 == 0) {
|
|
xtime.tv_sec++;
|
|
wall_to_monotonic.tv_sec--;
|
|
/*
|
|
* Use of time interpolator for a gradual change of
|
|
* time
|
|
*/
|
|
time_interpolator_update(NSEC_PER_SEC);
|
|
time_state = TIME_WAIT;
|
|
clock_was_set();
|
|
printk(KERN_NOTICE "Clock: deleting leap second "
|
|
"23:59:59 UTC\n");
|
|
}
|
|
break;
|
|
case TIME_OOP:
|
|
time_state = TIME_WAIT;
|
|
break;
|
|
case TIME_WAIT:
|
|
if (!(time_status & (STA_INS | STA_DEL)))
|
|
time_state = TIME_OK;
|
|
}
|
|
|
|
/*
|
|
* Compute the phase adjustment for the next second. In PLL mode, the
|
|
* offset is reduced by a fixed factor times the time constant. In FLL
|
|
* mode the offset is used directly. In either mode, the maximum phase
|
|
* adjustment for each second is clamped so as to spread the adjustment
|
|
* over not more than the number of seconds between updates.
|
|
*/
|
|
ltemp = time_offset;
|
|
if (!(time_status & STA_FLL))
|
|
ltemp = shift_right(ltemp, SHIFT_KG + time_constant);
|
|
ltemp = min(ltemp, (MAXPHASE / MINSEC) << SHIFT_UPDATE);
|
|
ltemp = max(ltemp, -(MAXPHASE / MINSEC) << SHIFT_UPDATE);
|
|
time_offset -= ltemp;
|
|
time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
|
|
|
|
/*
|
|
* Compute the frequency estimate and additional phase adjustment due
|
|
* to frequency error for the next second.
|
|
*/
|
|
ltemp = time_freq;
|
|
time_adj += shift_right(ltemp,(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE));
|
|
|
|
#if HZ == 100
|
|
/*
|
|
* Compensate for (HZ==100) != (1 << SHIFT_HZ). Add 25% and 3.125% to
|
|
* get 128.125; => only 0.125% error (p. 14)
|
|
*/
|
|
time_adj += shift_right(time_adj, 2) + shift_right(time_adj, 5);
|
|
#endif
|
|
#if HZ == 250
|
|
/*
|
|
* Compensate for (HZ==250) != (1 << SHIFT_HZ). Add 1.5625% and
|
|
* 0.78125% to get 255.85938; => only 0.05% error (p. 14)
|
|
*/
|
|
time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
|
|
#endif
|
|
#if HZ == 1000
|
|
/*
|
|
* Compensate for (HZ==1000) != (1 << SHIFT_HZ). Add 1.5625% and
|
|
* 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
|
|
*/
|
|
time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Returns how many microseconds we need to add to xtime this tick
|
|
* in doing an adjustment requested with adjtime.
|
|
*/
|
|
static long adjtime_adjustment(void)
|
|
{
|
|
long time_adjust_step;
|
|
|
|
time_adjust_step = time_adjust;
|
|
if (time_adjust_step) {
|
|
/*
|
|
* We are doing an adjtime thing. Prepare time_adjust_step to
|
|
* be within bounds. Note that a positive time_adjust means we
|
|
* want the clock to run faster.
|
|
*
|
|
* Limit the amount of the step to be in the range
|
|
* -tickadj .. +tickadj
|
|
*/
|
|
time_adjust_step = min(time_adjust_step, (long)tickadj);
|
|
time_adjust_step = max(time_adjust_step, (long)-tickadj);
|
|
}
|
|
return time_adjust_step;
|
|
}
|
|
|
|
/* in the NTP reference this is called "hardclock()" */
|
|
static void update_wall_time_one_tick(void)
|
|
{
|
|
long time_adjust_step, delta_nsec;
|
|
|
|
time_adjust_step = adjtime_adjustment();
|
|
if (time_adjust_step)
|
|
/* Reduce by this step the amount of time left */
|
|
time_adjust -= time_adjust_step;
|
|
delta_nsec = tick_nsec + time_adjust_step * 1000;
|
|
/*
|
|
* Advance the phase, once it gets to one microsecond, then
|
|
* advance the tick more.
|
|
*/
|
|
time_phase += time_adj;
|
|
if ((time_phase >= FINENSEC) || (time_phase <= -FINENSEC)) {
|
|
long ltemp = shift_right(time_phase, (SHIFT_SCALE - 10));
|
|
time_phase -= ltemp << (SHIFT_SCALE - 10);
|
|
delta_nsec += ltemp;
|
|
}
|
|
xtime.tv_nsec += delta_nsec;
|
|
time_interpolator_update(delta_nsec);
|
|
|
|
/* Changes by adjtime() do not take effect till next tick. */
|
|
if (time_next_adjust != 0) {
|
|
time_adjust = time_next_adjust;
|
|
time_next_adjust = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return how long ticks are at the moment, that is, how much time
|
|
* update_wall_time_one_tick will add to xtime next time we call it
|
|
* (assuming no calls to do_adjtimex in the meantime).
|
|
* The return value is in fixed-point nanoseconds with SHIFT_SCALE-10
|
|
* bits to the right of the binary point.
|
|
* This function has no side-effects.
|
|
*/
|
|
u64 current_tick_length(void)
|
|
{
|
|
long delta_nsec;
|
|
|
|
delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
|
|
return ((u64) delta_nsec << (SHIFT_SCALE - 10)) + time_adj;
|
|
}
|
|
|
|
/*
|
|
* Using a loop looks inefficient, but "ticks" is
|
|
* usually just one (we shouldn't be losing ticks,
|
|
* we're doing this this way mainly for interrupt
|
|
* latency reasons, not because we think we'll
|
|
* have lots of lost timer ticks
|
|
*/
|
|
static void update_wall_time(unsigned long ticks)
|
|
{
|
|
do {
|
|
ticks--;
|
|
update_wall_time_one_tick();
|
|
if (xtime.tv_nsec >= 1000000000) {
|
|
xtime.tv_nsec -= 1000000000;
|
|
xtime.tv_sec++;
|
|
second_overflow();
|
|
}
|
|
} while (ticks);
|
|
}
|
|
|
|
/*
|
|
* Called from the timer interrupt handler to charge one tick to the current
|
|
* process. user_tick is 1 if the tick is user time, 0 for system.
|
|
*/
|
|
void update_process_times(int user_tick)
|
|
{
|
|
struct task_struct *p = current;
|
|
int cpu = smp_processor_id();
|
|
|
|
/* Note: this timer irq context must be accounted for as well. */
|
|
if (user_tick)
|
|
account_user_time(p, jiffies_to_cputime(1));
|
|
else
|
|
account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
|
|
run_local_timers();
|
|
if (rcu_pending(cpu))
|
|
rcu_check_callbacks(cpu, user_tick);
|
|
scheduler_tick();
|
|
run_posix_cpu_timers(p);
|
|
}
|
|
|
|
/*
|
|
* Nr of active tasks - counted in fixed-point numbers
|
|
*/
|
|
static unsigned long count_active_tasks(void)
|
|
{
|
|
return nr_active() * FIXED_1;
|
|
}
|
|
|
|
/*
|
|
* Hmm.. Changed this, as the GNU make sources (load.c) seems to
|
|
* imply that avenrun[] is the standard name for this kind of thing.
|
|
* Nothing else seems to be standardized: the fractional size etc
|
|
* all seem to differ on different machines.
|
|
*
|
|
* Requires xtime_lock to access.
|
|
*/
|
|
unsigned long avenrun[3];
|
|
|
|
EXPORT_SYMBOL(avenrun);
|
|
|
|
/*
|
|
* calc_load - given tick count, update the avenrun load estimates.
|
|
* This is called while holding a write_lock on xtime_lock.
|
|
*/
|
|
static inline void calc_load(unsigned long ticks)
|
|
{
|
|
unsigned long active_tasks; /* fixed-point */
|
|
static int count = LOAD_FREQ;
|
|
|
|
count -= ticks;
|
|
if (count < 0) {
|
|
count += LOAD_FREQ;
|
|
active_tasks = count_active_tasks();
|
|
CALC_LOAD(avenrun[0], EXP_1, active_tasks);
|
|
CALC_LOAD(avenrun[1], EXP_5, active_tasks);
|
|
CALC_LOAD(avenrun[2], EXP_15, active_tasks);
|
|
}
|
|
}
|
|
|
|
/* jiffies at the most recent update of wall time */
|
|
unsigned long wall_jiffies = INITIAL_JIFFIES;
|
|
|
|
/*
|
|
* This read-write spinlock protects us from races in SMP while
|
|
* playing with xtime and avenrun.
|
|
*/
|
|
#ifndef ARCH_HAVE_XTIME_LOCK
|
|
seqlock_t xtime_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED;
|
|
|
|
EXPORT_SYMBOL(xtime_lock);
|
|
#endif
|
|
|
|
/*
|
|
* This function runs timers and the timer-tq in bottom half context.
|
|
*/
|
|
static void run_timer_softirq(struct softirq_action *h)
|
|
{
|
|
tvec_base_t *base = __get_cpu_var(tvec_bases);
|
|
|
|
hrtimer_run_queues();
|
|
if (time_after_eq(jiffies, base->timer_jiffies))
|
|
__run_timers(base);
|
|
}
|
|
|
|
/*
|
|
* Called by the local, per-CPU timer interrupt on SMP.
|
|
*/
|
|
void run_local_timers(void)
|
|
{
|
|
raise_softirq(TIMER_SOFTIRQ);
|
|
softlockup_tick();
|
|
}
|
|
|
|
/*
|
|
* Called by the timer interrupt. xtime_lock must already be taken
|
|
* by the timer IRQ!
|
|
*/
|
|
static inline void update_times(void)
|
|
{
|
|
unsigned long ticks;
|
|
|
|
ticks = jiffies - wall_jiffies;
|
|
if (ticks) {
|
|
wall_jiffies += ticks;
|
|
update_wall_time(ticks);
|
|
}
|
|
calc_load(ticks);
|
|
}
|
|
|
|
/*
|
|
* The 64-bit jiffies value is not atomic - you MUST NOT read it
|
|
* without sampling the sequence number in xtime_lock.
|
|
* jiffies is defined in the linker script...
|
|
*/
|
|
|
|
void do_timer(struct pt_regs *regs)
|
|
{
|
|
jiffies_64++;
|
|
/* prevent loading jiffies before storing new jiffies_64 value. */
|
|
barrier();
|
|
update_times();
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_ALARM
|
|
|
|
/*
|
|
* For backwards compatibility? This can be done in libc so Alpha
|
|
* and all newer ports shouldn't need it.
|
|
*/
|
|
asmlinkage unsigned long sys_alarm(unsigned int seconds)
|
|
{
|
|
return alarm_setitimer(seconds);
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifndef __alpha__
|
|
|
|
/*
|
|
* The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
|
|
* should be moved into arch/i386 instead?
|
|
*/
|
|
|
|
/**
|
|
* sys_getpid - return the thread group id of the current process
|
|
*
|
|
* Note, despite the name, this returns the tgid not the pid. The tgid and
|
|
* the pid are identical unless CLONE_THREAD was specified on clone() in
|
|
* which case the tgid is the same in all threads of the same group.
|
|
*
|
|
* This is SMP safe as current->tgid does not change.
|
|
*/
|
|
asmlinkage long sys_getpid(void)
|
|
{
|
|
return current->tgid;
|
|
}
|
|
|
|
/*
|
|
* Accessing ->group_leader->real_parent is not SMP-safe, it could
|
|
* change from under us. However, rather than getting any lock
|
|
* we can use an optimistic algorithm: get the parent
|
|
* pid, and go back and check that the parent is still
|
|
* the same. If it has changed (which is extremely unlikely
|
|
* indeed), we just try again..
|
|
*
|
|
* NOTE! This depends on the fact that even if we _do_
|
|
* get an old value of "parent", we can happily dereference
|
|
* the pointer (it was and remains a dereferencable kernel pointer
|
|
* no matter what): we just can't necessarily trust the result
|
|
* until we know that the parent pointer is valid.
|
|
*
|
|
* NOTE2: ->group_leader never changes from under us.
|
|
*/
|
|
asmlinkage long sys_getppid(void)
|
|
{
|
|
int pid;
|
|
struct task_struct *me = current;
|
|
struct task_struct *parent;
|
|
|
|
parent = me->group_leader->real_parent;
|
|
for (;;) {
|
|
pid = parent->tgid;
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
|
|
{
|
|
struct task_struct *old = parent;
|
|
|
|
/*
|
|
* Make sure we read the pid before re-reading the
|
|
* parent pointer:
|
|
*/
|
|
smp_rmb();
|
|
parent = me->group_leader->real_parent;
|
|
if (old != parent)
|
|
continue;
|
|
}
|
|
#endif
|
|
break;
|
|
}
|
|
return pid;
|
|
}
|
|
|
|
asmlinkage long sys_getuid(void)
|
|
{
|
|
/* Only we change this so SMP safe */
|
|
return current->uid;
|
|
}
|
|
|
|
asmlinkage long sys_geteuid(void)
|
|
{
|
|
/* Only we change this so SMP safe */
|
|
return current->euid;
|
|
}
|
|
|
|
asmlinkage long sys_getgid(void)
|
|
{
|
|
/* Only we change this so SMP safe */
|
|
return current->gid;
|
|
}
|
|
|
|
asmlinkage long sys_getegid(void)
|
|
{
|
|
/* Only we change this so SMP safe */
|
|
return current->egid;
|
|
}
|
|
|
|
#endif
|
|
|
|
static void process_timeout(unsigned long __data)
|
|
{
|
|
wake_up_process((task_t *)__data);
|
|
}
|
|
|
|
/**
|
|
* schedule_timeout - sleep until timeout
|
|
* @timeout: timeout value in jiffies
|
|
*
|
|
* Make the current task sleep until @timeout jiffies have
|
|
* elapsed. The routine will return immediately unless
|
|
* the current task state has been set (see set_current_state()).
|
|
*
|
|
* You can set the task state as follows -
|
|
*
|
|
* %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
|
|
* pass before the routine returns. The routine will return 0
|
|
*
|
|
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
|
|
* delivered to the current task. In this case the remaining time
|
|
* in jiffies will be returned, or 0 if the timer expired in time
|
|
*
|
|
* The current task state is guaranteed to be TASK_RUNNING when this
|
|
* routine returns.
|
|
*
|
|
* Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
|
|
* the CPU away without a bound on the timeout. In this case the return
|
|
* value will be %MAX_SCHEDULE_TIMEOUT.
|
|
*
|
|
* In all cases the return value is guaranteed to be non-negative.
|
|
*/
|
|
fastcall signed long __sched schedule_timeout(signed long timeout)
|
|
{
|
|
struct timer_list timer;
|
|
unsigned long expire;
|
|
|
|
switch (timeout)
|
|
{
|
|
case MAX_SCHEDULE_TIMEOUT:
|
|
/*
|
|
* These two special cases are useful to be comfortable
|
|
* in the caller. Nothing more. We could take
|
|
* MAX_SCHEDULE_TIMEOUT from one of the negative value
|
|
* but I' d like to return a valid offset (>=0) to allow
|
|
* the caller to do everything it want with the retval.
|
|
*/
|
|
schedule();
|
|
goto out;
|
|
default:
|
|
/*
|
|
* Another bit of PARANOID. Note that the retval will be
|
|
* 0 since no piece of kernel is supposed to do a check
|
|
* for a negative retval of schedule_timeout() (since it
|
|
* should never happens anyway). You just have the printk()
|
|
* that will tell you if something is gone wrong and where.
|
|
*/
|
|
if (timeout < 0)
|
|
{
|
|
printk(KERN_ERR "schedule_timeout: wrong timeout "
|
|
"value %lx from %p\n", timeout,
|
|
__builtin_return_address(0));
|
|
current->state = TASK_RUNNING;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
expire = timeout + jiffies;
|
|
|
|
setup_timer(&timer, process_timeout, (unsigned long)current);
|
|
__mod_timer(&timer, expire);
|
|
schedule();
|
|
del_singleshot_timer_sync(&timer);
|
|
|
|
timeout = expire - jiffies;
|
|
|
|
out:
|
|
return timeout < 0 ? 0 : timeout;
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout);
|
|
|
|
/*
|
|
* We can use __set_current_state() here because schedule_timeout() calls
|
|
* schedule() unconditionally.
|
|
*/
|
|
signed long __sched schedule_timeout_interruptible(signed long timeout)
|
|
{
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
return schedule_timeout(timeout);
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout_interruptible);
|
|
|
|
signed long __sched schedule_timeout_uninterruptible(signed long timeout)
|
|
{
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
return schedule_timeout(timeout);
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout_uninterruptible);
|
|
|
|
/* Thread ID - the internal kernel "pid" */
|
|
asmlinkage long sys_gettid(void)
|
|
{
|
|
return current->pid;
|
|
}
|
|
|
|
/*
|
|
* sys_sysinfo - fill in sysinfo struct
|
|
*/
|
|
asmlinkage long sys_sysinfo(struct sysinfo __user *info)
|
|
{
|
|
struct sysinfo val;
|
|
unsigned long mem_total, sav_total;
|
|
unsigned int mem_unit, bitcount;
|
|
unsigned long seq;
|
|
|
|
memset((char *)&val, 0, sizeof(struct sysinfo));
|
|
|
|
do {
|
|
struct timespec tp;
|
|
seq = read_seqbegin(&xtime_lock);
|
|
|
|
/*
|
|
* This is annoying. The below is the same thing
|
|
* posix_get_clock_monotonic() does, but it wants to
|
|
* take the lock which we want to cover the loads stuff
|
|
* too.
|
|
*/
|
|
|
|
getnstimeofday(&tp);
|
|
tp.tv_sec += wall_to_monotonic.tv_sec;
|
|
tp.tv_nsec += wall_to_monotonic.tv_nsec;
|
|
if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
|
|
tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
|
|
tp.tv_sec++;
|
|
}
|
|
val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
|
|
|
|
val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
|
|
val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
|
|
val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
|
|
|
|
val.procs = nr_threads;
|
|
} while (read_seqretry(&xtime_lock, seq));
|
|
|
|
si_meminfo(&val);
|
|
si_swapinfo(&val);
|
|
|
|
/*
|
|
* If the sum of all the available memory (i.e. ram + swap)
|
|
* is less than can be stored in a 32 bit unsigned long then
|
|
* we can be binary compatible with 2.2.x kernels. If not,
|
|
* well, in that case 2.2.x was broken anyways...
|
|
*
|
|
* -Erik Andersen <andersee@debian.org>
|
|
*/
|
|
|
|
mem_total = val.totalram + val.totalswap;
|
|
if (mem_total < val.totalram || mem_total < val.totalswap)
|
|
goto out;
|
|
bitcount = 0;
|
|
mem_unit = val.mem_unit;
|
|
while (mem_unit > 1) {
|
|
bitcount++;
|
|
mem_unit >>= 1;
|
|
sav_total = mem_total;
|
|
mem_total <<= 1;
|
|
if (mem_total < sav_total)
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* If mem_total did not overflow, multiply all memory values by
|
|
* val.mem_unit and set it to 1. This leaves things compatible
|
|
* with 2.2.x, and also retains compatibility with earlier 2.4.x
|
|
* kernels...
|
|
*/
|
|
|
|
val.mem_unit = 1;
|
|
val.totalram <<= bitcount;
|
|
val.freeram <<= bitcount;
|
|
val.sharedram <<= bitcount;
|
|
val.bufferram <<= bitcount;
|
|
val.totalswap <<= bitcount;
|
|
val.freeswap <<= bitcount;
|
|
val.totalhigh <<= bitcount;
|
|
val.freehigh <<= bitcount;
|
|
|
|
out:
|
|
if (copy_to_user(info, &val, sizeof(struct sysinfo)))
|
|
return -EFAULT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __devinit init_timers_cpu(int cpu)
|
|
{
|
|
int j;
|
|
tvec_base_t *base;
|
|
static char __devinitdata tvec_base_done[NR_CPUS];
|
|
|
|
if (!tvec_base_done[cpu]) {
|
|
static char boot_done;
|
|
|
|
if (boot_done) {
|
|
/*
|
|
* The APs use this path later in boot
|
|
*/
|
|
base = kmalloc_node(sizeof(*base), GFP_KERNEL,
|
|
cpu_to_node(cpu));
|
|
if (!base)
|
|
return -ENOMEM;
|
|
memset(base, 0, sizeof(*base));
|
|
per_cpu(tvec_bases, cpu) = base;
|
|
} else {
|
|
/*
|
|
* This is for the boot CPU - we use compile-time
|
|
* static initialisation because per-cpu memory isn't
|
|
* ready yet and because the memory allocators are not
|
|
* initialised either.
|
|
*/
|
|
boot_done = 1;
|
|
base = &boot_tvec_bases;
|
|
}
|
|
tvec_base_done[cpu] = 1;
|
|
} else {
|
|
base = per_cpu(tvec_bases, cpu);
|
|
}
|
|
|
|
spin_lock_init(&base->lock);
|
|
for (j = 0; j < TVN_SIZE; j++) {
|
|
INIT_LIST_HEAD(base->tv5.vec + j);
|
|
INIT_LIST_HEAD(base->tv4.vec + j);
|
|
INIT_LIST_HEAD(base->tv3.vec + j);
|
|
INIT_LIST_HEAD(base->tv2.vec + j);
|
|
}
|
|
for (j = 0; j < TVR_SIZE; j++)
|
|
INIT_LIST_HEAD(base->tv1.vec + j);
|
|
|
|
base->timer_jiffies = jiffies;
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
|
|
{
|
|
struct timer_list *timer;
|
|
|
|
while (!list_empty(head)) {
|
|
timer = list_entry(head->next, struct timer_list, entry);
|
|
detach_timer(timer, 0);
|
|
timer->base = new_base;
|
|
internal_add_timer(new_base, timer);
|
|
}
|
|
}
|
|
|
|
static void __devinit migrate_timers(int cpu)
|
|
{
|
|
tvec_base_t *old_base;
|
|
tvec_base_t *new_base;
|
|
int i;
|
|
|
|
BUG_ON(cpu_online(cpu));
|
|
old_base = per_cpu(tvec_bases, cpu);
|
|
new_base = get_cpu_var(tvec_bases);
|
|
|
|
local_irq_disable();
|
|
spin_lock(&new_base->lock);
|
|
spin_lock(&old_base->lock);
|
|
|
|
BUG_ON(old_base->running_timer);
|
|
|
|
for (i = 0; i < TVR_SIZE; i++)
|
|
migrate_timer_list(new_base, old_base->tv1.vec + i);
|
|
for (i = 0; i < TVN_SIZE; i++) {
|
|
migrate_timer_list(new_base, old_base->tv2.vec + i);
|
|
migrate_timer_list(new_base, old_base->tv3.vec + i);
|
|
migrate_timer_list(new_base, old_base->tv4.vec + i);
|
|
migrate_timer_list(new_base, old_base->tv5.vec + i);
|
|
}
|
|
|
|
spin_unlock(&old_base->lock);
|
|
spin_unlock(&new_base->lock);
|
|
local_irq_enable();
|
|
put_cpu_var(tvec_bases);
|
|
}
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
static int __devinit timer_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
long cpu = (long)hcpu;
|
|
switch(action) {
|
|
case CPU_UP_PREPARE:
|
|
if (init_timers_cpu(cpu) < 0)
|
|
return NOTIFY_BAD;
|
|
break;
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
case CPU_DEAD:
|
|
migrate_timers(cpu);
|
|
break;
|
|
#endif
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block __devinitdata timers_nb = {
|
|
.notifier_call = timer_cpu_notify,
|
|
};
|
|
|
|
|
|
void __init init_timers(void)
|
|
{
|
|
timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
|
|
(void *)(long)smp_processor_id());
|
|
register_cpu_notifier(&timers_nb);
|
|
open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
|
|
}
|
|
|
|
#ifdef CONFIG_TIME_INTERPOLATION
|
|
|
|
struct time_interpolator *time_interpolator __read_mostly;
|
|
static struct time_interpolator *time_interpolator_list __read_mostly;
|
|
static DEFINE_SPINLOCK(time_interpolator_lock);
|
|
|
|
static inline u64 time_interpolator_get_cycles(unsigned int src)
|
|
{
|
|
unsigned long (*x)(void);
|
|
|
|
switch (src)
|
|
{
|
|
case TIME_SOURCE_FUNCTION:
|
|
x = time_interpolator->addr;
|
|
return x();
|
|
|
|
case TIME_SOURCE_MMIO64 :
|
|
return readq_relaxed((void __iomem *)time_interpolator->addr);
|
|
|
|
case TIME_SOURCE_MMIO32 :
|
|
return readl_relaxed((void __iomem *)time_interpolator->addr);
|
|
|
|
default: return get_cycles();
|
|
}
|
|
}
|
|
|
|
static inline u64 time_interpolator_get_counter(int writelock)
|
|
{
|
|
unsigned int src = time_interpolator->source;
|
|
|
|
if (time_interpolator->jitter)
|
|
{
|
|
u64 lcycle;
|
|
u64 now;
|
|
|
|
do {
|
|
lcycle = time_interpolator->last_cycle;
|
|
now = time_interpolator_get_cycles(src);
|
|
if (lcycle && time_after(lcycle, now))
|
|
return lcycle;
|
|
|
|
/* When holding the xtime write lock, there's no need
|
|
* to add the overhead of the cmpxchg. Readers are
|
|
* force to retry until the write lock is released.
|
|
*/
|
|
if (writelock) {
|
|
time_interpolator->last_cycle = now;
|
|
return now;
|
|
}
|
|
/* Keep track of the last timer value returned. The use of cmpxchg here
|
|
* will cause contention in an SMP environment.
|
|
*/
|
|
} while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
|
|
return now;
|
|
}
|
|
else
|
|
return time_interpolator_get_cycles(src);
|
|
}
|
|
|
|
void time_interpolator_reset(void)
|
|
{
|
|
time_interpolator->offset = 0;
|
|
time_interpolator->last_counter = time_interpolator_get_counter(1);
|
|
}
|
|
|
|
#define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
|
|
|
|
unsigned long time_interpolator_get_offset(void)
|
|
{
|
|
/* If we do not have a time interpolator set up then just return zero */
|
|
if (!time_interpolator)
|
|
return 0;
|
|
|
|
return time_interpolator->offset +
|
|
GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
|
|
}
|
|
|
|
#define INTERPOLATOR_ADJUST 65536
|
|
#define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
|
|
|
|
static void time_interpolator_update(long delta_nsec)
|
|
{
|
|
u64 counter;
|
|
unsigned long offset;
|
|
|
|
/* If there is no time interpolator set up then do nothing */
|
|
if (!time_interpolator)
|
|
return;
|
|
|
|
/*
|
|
* The interpolator compensates for late ticks by accumulating the late
|
|
* time in time_interpolator->offset. A tick earlier than expected will
|
|
* lead to a reset of the offset and a corresponding jump of the clock
|
|
* forward. Again this only works if the interpolator clock is running
|
|
* slightly slower than the regular clock and the tuning logic insures
|
|
* that.
|
|
*/
|
|
|
|
counter = time_interpolator_get_counter(1);
|
|
offset = time_interpolator->offset +
|
|
GET_TI_NSECS(counter, time_interpolator);
|
|
|
|
if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
|
|
time_interpolator->offset = offset - delta_nsec;
|
|
else {
|
|
time_interpolator->skips++;
|
|
time_interpolator->ns_skipped += delta_nsec - offset;
|
|
time_interpolator->offset = 0;
|
|
}
|
|
time_interpolator->last_counter = counter;
|
|
|
|
/* Tuning logic for time interpolator invoked every minute or so.
|
|
* Decrease interpolator clock speed if no skips occurred and an offset is carried.
|
|
* Increase interpolator clock speed if we skip too much time.
|
|
*/
|
|
if (jiffies % INTERPOLATOR_ADJUST == 0)
|
|
{
|
|
if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec)
|
|
time_interpolator->nsec_per_cyc--;
|
|
if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
|
|
time_interpolator->nsec_per_cyc++;
|
|
time_interpolator->skips = 0;
|
|
time_interpolator->ns_skipped = 0;
|
|
}
|
|
}
|
|
|
|
static inline int
|
|
is_better_time_interpolator(struct time_interpolator *new)
|
|
{
|
|
if (!time_interpolator)
|
|
return 1;
|
|
return new->frequency > 2*time_interpolator->frequency ||
|
|
(unsigned long)new->drift < (unsigned long)time_interpolator->drift;
|
|
}
|
|
|
|
void
|
|
register_time_interpolator(struct time_interpolator *ti)
|
|
{
|
|
unsigned long flags;
|
|
|
|
/* Sanity check */
|
|
BUG_ON(ti->frequency == 0 || ti->mask == 0);
|
|
|
|
ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
|
|
spin_lock(&time_interpolator_lock);
|
|
write_seqlock_irqsave(&xtime_lock, flags);
|
|
if (is_better_time_interpolator(ti)) {
|
|
time_interpolator = ti;
|
|
time_interpolator_reset();
|
|
}
|
|
write_sequnlock_irqrestore(&xtime_lock, flags);
|
|
|
|
ti->next = time_interpolator_list;
|
|
time_interpolator_list = ti;
|
|
spin_unlock(&time_interpolator_lock);
|
|
}
|
|
|
|
void
|
|
unregister_time_interpolator(struct time_interpolator *ti)
|
|
{
|
|
struct time_interpolator *curr, **prev;
|
|
unsigned long flags;
|
|
|
|
spin_lock(&time_interpolator_lock);
|
|
prev = &time_interpolator_list;
|
|
for (curr = *prev; curr; curr = curr->next) {
|
|
if (curr == ti) {
|
|
*prev = curr->next;
|
|
break;
|
|
}
|
|
prev = &curr->next;
|
|
}
|
|
|
|
write_seqlock_irqsave(&xtime_lock, flags);
|
|
if (ti == time_interpolator) {
|
|
/* we lost the best time-interpolator: */
|
|
time_interpolator = NULL;
|
|
/* find the next-best interpolator */
|
|
for (curr = time_interpolator_list; curr; curr = curr->next)
|
|
if (is_better_time_interpolator(curr))
|
|
time_interpolator = curr;
|
|
time_interpolator_reset();
|
|
}
|
|
write_sequnlock_irqrestore(&xtime_lock, flags);
|
|
spin_unlock(&time_interpolator_lock);
|
|
}
|
|
#endif /* CONFIG_TIME_INTERPOLATION */
|
|
|
|
/**
|
|
* msleep - sleep safely even with waitqueue interruptions
|
|
* @msecs: Time in milliseconds to sleep for
|
|
*/
|
|
void msleep(unsigned int msecs)
|
|
{
|
|
unsigned long timeout = msecs_to_jiffies(msecs) + 1;
|
|
|
|
while (timeout)
|
|
timeout = schedule_timeout_uninterruptible(timeout);
|
|
}
|
|
|
|
EXPORT_SYMBOL(msleep);
|
|
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/**
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* msleep_interruptible - sleep waiting for signals
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* @msecs: Time in milliseconds to sleep for
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*/
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unsigned long msleep_interruptible(unsigned int msecs)
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{
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unsigned long timeout = msecs_to_jiffies(msecs) + 1;
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while (timeout && !signal_pending(current))
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timeout = schedule_timeout_interruptible(timeout);
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return jiffies_to_msecs(timeout);
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}
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EXPORT_SYMBOL(msleep_interruptible);
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