[S390] ap: Use high-resolution timer for polling
The ap poll mechanism is converted to use a high-resolution timer for polling. This allows more specific polling. With this a new sysfs attribute is introduced to specify the polling rate in nanoseconds. Signed-off-by: Felix Beck <felix.beck@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>hifive-unleashed-5.1
Felix Beck
Heiko Carstens
parent
ad211790c0
commit
fe13723061
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@ -34,13 +34,15 @@
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#include <linux/mutex.h>
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#include <asm/s390_rdev.h>
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#include <asm/reset.h>
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#include <linux/hrtimer.h>
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#include <linux/ktime.h>
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#include "ap_bus.h"
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/* Some prototypes. */
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static void ap_scan_bus(struct work_struct *);
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static void ap_poll_all(unsigned long);
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static void ap_poll_timeout(unsigned long);
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static enum hrtimer_restart ap_poll_timeout(struct hrtimer *);
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static int ap_poll_thread_start(void);
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static void ap_poll_thread_stop(void);
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static void ap_request_timeout(unsigned long);
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@ -80,12 +82,15 @@ static DECLARE_WORK(ap_config_work, ap_scan_bus);
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/*
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* Tasklet & timer for AP request polling.
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*/
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static struct timer_list ap_poll_timer = TIMER_INITIALIZER(ap_poll_timeout,0,0);
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static DECLARE_TASKLET(ap_tasklet, ap_poll_all, 0);
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static atomic_t ap_poll_requests = ATOMIC_INIT(0);
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static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait);
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static struct task_struct *ap_poll_kthread = NULL;
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static DEFINE_MUTEX(ap_poll_thread_mutex);
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static struct hrtimer ap_poll_timer;
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/* In LPAR poll with 4kHz frequency. Poll every 250000 nanoseconds.
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* If z/VM change to 1500000 nanoseconds to adjust to z/VM polling.*/
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static unsigned long long poll_timeout = 250000;
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/**
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* ap_intructions_available() - Test if AP instructions are available.
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@ -636,11 +641,39 @@ static ssize_t ap_poll_thread_store(struct bus_type *bus,
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static BUS_ATTR(poll_thread, 0644, ap_poll_thread_show, ap_poll_thread_store);
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static ssize_t poll_timeout_show(struct bus_type *bus, char *buf)
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{
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return snprintf(buf, PAGE_SIZE, "%llu\n", poll_timeout);
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}
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static ssize_t poll_timeout_store(struct bus_type *bus, const char *buf,
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size_t count)
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{
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unsigned long long time;
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ktime_t hr_time;
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/* 120 seconds = maximum poll interval */
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if (sscanf(buf, "%llu\n", &time) != 1 || time < 1 || time > 120000000000)
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return -EINVAL;
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poll_timeout = time;
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hr_time = ktime_set(0, poll_timeout);
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if (!hrtimer_is_queued(&ap_poll_timer) ||
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!hrtimer_forward(&ap_poll_timer, ap_poll_timer.expires, hr_time)) {
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ap_poll_timer.expires = hr_time;
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hrtimer_start(&ap_poll_timer, hr_time, HRTIMER_MODE_ABS);
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}
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return count;
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}
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static BUS_ATTR(poll_timeout, 0644, poll_timeout_show, poll_timeout_store);
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static struct bus_attribute *const ap_bus_attrs[] = {
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&bus_attr_ap_domain,
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&bus_attr_config_time,
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&bus_attr_poll_thread,
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NULL
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&bus_attr_poll_timeout,
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NULL,
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};
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/**
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@ -895,9 +928,10 @@ ap_config_timeout(unsigned long ptr)
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*/
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static inline void ap_schedule_poll_timer(void)
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{
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if (timer_pending(&ap_poll_timer))
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if (hrtimer_is_queued(&ap_poll_timer))
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return;
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mod_timer(&ap_poll_timer, jiffies + AP_POLL_TIME);
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hrtimer_start(&ap_poll_timer, ktime_set(0, poll_timeout),
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HRTIMER_MODE_ABS);
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}
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/**
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@ -1115,13 +1149,14 @@ EXPORT_SYMBOL(ap_cancel_message);
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/**
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* ap_poll_timeout(): AP receive polling for finished AP requests.
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* @unused: Unused variable.
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* @unused: Unused pointer.
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*
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* Schedules the AP tasklet.
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* Schedules the AP tasklet using a high resolution timer.
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*/
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static void ap_poll_timeout(unsigned long unused)
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static enum hrtimer_restart ap_poll_timeout(struct hrtimer *unused)
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{
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tasklet_schedule(&ap_tasklet);
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return HRTIMER_NORESTART;
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}
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/**
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@ -1344,6 +1379,14 @@ int __init ap_module_init(void)
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ap_config_timer.expires = jiffies + ap_config_time * HZ;
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add_timer(&ap_config_timer);
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/* Setup the high resultion poll timer.
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* If we are running under z/VM adjust polling to z/VM polling rate.
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*/
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if (MACHINE_IS_VM)
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poll_timeout = 1500000;
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hrtimer_init(&ap_poll_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
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ap_poll_timer.function = ap_poll_timeout;
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/* Start the low priority AP bus poll thread. */
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if (ap_thread_flag) {
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rc = ap_poll_thread_start();
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@ -1355,7 +1398,7 @@ int __init ap_module_init(void)
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out_work:
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del_timer_sync(&ap_config_timer);
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del_timer_sync(&ap_poll_timer);
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hrtimer_cancel(&ap_poll_timer);
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destroy_workqueue(ap_work_queue);
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out_root:
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s390_root_dev_unregister(ap_root_device);
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@ -1386,7 +1429,7 @@ void ap_module_exit(void)
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ap_reset_domain();
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ap_poll_thread_stop();
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del_timer_sync(&ap_config_timer);
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del_timer_sync(&ap_poll_timer);
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hrtimer_cancel(&ap_poll_timer);
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destroy_workqueue(ap_work_queue);
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tasklet_kill(&ap_tasklet);
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s390_root_dev_unregister(ap_root_device);
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