8f4d37ec07
Use HR-timers (when available) to deliver an accurate preemption tick. The regular scheduler tick that runs at 1/HZ can be too coarse when nice level are used. The fairness system will still keep the cpu utilisation 'fair' by then delaying the task that got an excessive amount of CPU time but try to minimize this by delivering preemption points spot-on. The average frequency of this extra interrupt is sched_latency / nr_latency. Which need not be higher than 1/HZ, its just that the distribution within the sched_latency period is important. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
183 lines
5.5 KiB
C
183 lines
5.5 KiB
C
/* thread_info.h: i386 low-level thread information
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* - Incorporating suggestions made by Linus Torvalds and Dave Miller
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*/
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#ifndef _ASM_THREAD_INFO_H
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#define _ASM_THREAD_INFO_H
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#ifdef __KERNEL__
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#include <linux/compiler.h>
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#include <asm/page.h>
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#ifndef __ASSEMBLY__
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#include <asm/processor.h>
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#endif
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/*
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* low level task data that entry.S needs immediate access to
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* - this struct should fit entirely inside of one cache line
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* - this struct shares the supervisor stack pages
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* - if the contents of this structure are changed, the assembly constants must also be changed
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*/
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#ifndef __ASSEMBLY__
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struct thread_info {
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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unsigned long flags; /* low level flags */
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unsigned long status; /* thread-synchronous flags */
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__u32 cpu; /* current CPU */
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int preempt_count; /* 0 => preemptable, <0 => BUG */
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mm_segment_t addr_limit; /* thread address space:
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0-0xBFFFFFFF for user-thead
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0-0xFFFFFFFF for kernel-thread
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*/
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void *sysenter_return;
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struct restart_block restart_block;
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unsigned long previous_esp; /* ESP of the previous stack in case
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of nested (IRQ) stacks
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*/
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__u8 supervisor_stack[0];
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};
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#else /* !__ASSEMBLY__ */
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#include <asm/asm-offsets.h>
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#endif
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#define PREEMPT_ACTIVE 0x10000000
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#ifdef CONFIG_4KSTACKS
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#define THREAD_SIZE (4096)
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#else
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#define THREAD_SIZE (8192)
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#endif
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#define STACK_WARN (THREAD_SIZE/8)
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/*
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* macros/functions for gaining access to the thread information structure
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*
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* preempt_count needs to be 1 initially, until the scheduler is functional.
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*/
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#ifndef __ASSEMBLY__
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.exec_domain = &default_exec_domain, \
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.flags = 0, \
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.cpu = 0, \
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.preempt_count = 1, \
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.addr_limit = KERNEL_DS, \
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.restart_block = { \
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.fn = do_no_restart_syscall, \
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}, \
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}
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#define init_thread_info (init_thread_union.thread_info)
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#define init_stack (init_thread_union.stack)
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/* how to get the current stack pointer from C */
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register unsigned long current_stack_pointer asm("esp") __attribute_used__;
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/* how to get the thread information struct from C */
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static inline struct thread_info *current_thread_info(void)
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{
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return (struct thread_info *)(current_stack_pointer & ~(THREAD_SIZE - 1));
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}
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/* thread information allocation */
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#ifdef CONFIG_DEBUG_STACK_USAGE
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#define alloc_thread_info(tsk) ((struct thread_info *) \
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__get_free_pages(GFP_KERNEL| __GFP_ZERO, get_order(THREAD_SIZE)))
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#else
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#define alloc_thread_info(tsk) ((struct thread_info *) \
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__get_free_pages(GFP_KERNEL, get_order(THREAD_SIZE)))
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#endif
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#define free_thread_info(info) free_pages((unsigned long)(info), get_order(THREAD_SIZE))
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#else /* !__ASSEMBLY__ */
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/* how to get the thread information struct from ASM */
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#define GET_THREAD_INFO(reg) \
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movl $-THREAD_SIZE, reg; \
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andl %esp, reg
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/* use this one if reg already contains %esp */
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#define GET_THREAD_INFO_WITH_ESP(reg) \
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andl $-THREAD_SIZE, reg
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#endif
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/*
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* thread information flags
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* - these are process state flags that various assembly files may need to access
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* - pending work-to-be-done flags are in LSW
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* - other flags in MSW
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_SINGLESTEP 3 /* restore singlestep on return to user mode */
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#define TIF_IRET 4 /* return with iret */
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#define TIF_SYSCALL_EMU 5 /* syscall emulation active */
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#define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */
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#define TIF_SECCOMP 7 /* secure computing */
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#define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal() */
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#define TIF_HRTICK_RESCHED 9 /* reprogram hrtick timer */
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#define TIF_MEMDIE 16
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#define TIF_DEBUG 17 /* uses debug registers */
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#define TIF_IO_BITMAP 18 /* uses I/O bitmap */
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#define TIF_FREEZE 19 /* is freezing for suspend */
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#define TIF_NOTSC 20 /* TSC is not accessible in userland */
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#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
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#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
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#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
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#define _TIF_IRET (1<<TIF_IRET)
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#define _TIF_SYSCALL_EMU (1<<TIF_SYSCALL_EMU)
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#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
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#define _TIF_SECCOMP (1<<TIF_SECCOMP)
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#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
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#define _TIF_HRTICK_RESCHED (1<<TIF_HRTICK_RESCHED)
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#define _TIF_DEBUG (1<<TIF_DEBUG)
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#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
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#define _TIF_FREEZE (1<<TIF_FREEZE)
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#define _TIF_NOTSC (1<<TIF_NOTSC)
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/* work to do on interrupt/exception return */
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#define _TIF_WORK_MASK \
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(0x0000FFFF & ~(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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_TIF_SECCOMP | _TIF_SYSCALL_EMU))
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/* work to do on any return to u-space */
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#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
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/* flags to check in __switch_to() */
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#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG)
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#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC)
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/*
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* Thread-synchronous status.
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*
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* This is different from the flags in that nobody else
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* ever touches our thread-synchronous status, so we don't
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* have to worry about atomic accesses.
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*/
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#define TS_USEDFPU 0x0001 /* FPU was used by this task this quantum (SMP) */
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#define TS_POLLING 0x0002 /* True if in idle loop and not sleeping */
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#define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
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#endif /* __KERNEL__ */
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#endif /* _ASM_THREAD_INFO_H */
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