From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Rusty Russell <rusty@rustcorp.com.au>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Namhyung Kim <namhyung@kernel.org>
Subject: [Patch 5/7] watchdog: Use hotplug thread infrastructure
Date: Mon, 16 Jul 2012 10:42:38 -0000 [thread overview]
Message-ID: <20120716103948.563736676@linutronix.de> (raw)
In-Reply-To: 20120716103749.122800930@linutronix.de
[-- Attachment #1: watchdog-use-smb-kthreads.patch --]
[-- Type: text/plain, Size: 10552 bytes --]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/watchdog.c | 264 ++++++++++++++++++------------------------------------
1 file changed, 89 insertions(+), 175 deletions(-)
Index: tip/kernel/watchdog.c
===================================================================
--- tip.orig/kernel/watchdog.c
+++ tip/kernel/watchdog.c
@@ -22,6 +22,7 @@
#include <linux/notifier.h>
#include <linux/module.h>
#include <linux/sysctl.h>
+#include <linux/smpboot.h>
#include <asm/irq_regs.h>
#include <linux/kvm_para.h>
@@ -29,16 +30,18 @@
int watchdog_enabled = 1;
int __read_mostly watchdog_thresh = 10;
+static int __read_mostly watchdog_disabled;
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
static DEFINE_PER_CPU(bool, softlockup_touch_sync);
static DEFINE_PER_CPU(bool, soft_watchdog_warn);
+static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
+static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);
#ifdef CONFIG_HARDLOCKUP_DETECTOR
static DEFINE_PER_CPU(bool, hard_watchdog_warn);
static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
-static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
#endif
@@ -248,13 +251,15 @@ static void watchdog_overflow_callback(s
__this_cpu_write(hard_watchdog_warn, false);
return;
}
+#endif /* CONFIG_HARDLOCKUP_DETECTOR */
+
static void watchdog_interrupt_count(void)
{
__this_cpu_inc(hrtimer_interrupts);
}
-#else
-static inline void watchdog_interrupt_count(void) { return; }
-#endif /* CONFIG_HARDLOCKUP_DETECTOR */
+
+static int watchdog_nmi_enable(unsigned int cpu);
+static void watchdog_nmi_disable(unsigned int cpu);
/* watchdog kicker functions */
static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
@@ -327,52 +332,71 @@ static enum hrtimer_restart watchdog_tim
return HRTIMER_RESTART;
}
+static void watchdog_set_prio(unsigned int policy, unsigned int prio)
+{
+ struct sched_param param = { .sched_priority = prio };
-/*
- * The watchdog thread - touches the timestamp.
- */
-static int watchdog(void *unused)
+ sched_setscheduler(current, policy, ¶m);
+}
+
+static void watchdog_enable(unsigned int cpu)
{
- struct sched_param param = { .sched_priority = 0 };
struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
- /* initialize timestamp */
- __touch_watchdog();
+ if (!watchdog_enabled) {
+ kthread_park(current);
+ return;
+ }
+
+ /* Enable the perf event */
+ watchdog_nmi_enable(cpu);
/* kick off the timer for the hardlockup detector */
+ hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ hrtimer->function = watchdog_timer_fn;
+
/* done here because hrtimer_start can only pin to smp_processor_id() */
hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
HRTIMER_MODE_REL_PINNED);
- set_current_state(TASK_INTERRUPTIBLE);
- /*
- * Run briefly (kicked by the hrtimer callback function) once every
- * get_sample_period() seconds (4 seconds by default) to reset the
- * softlockup timestamp. If this gets delayed for more than
- * 2*watchdog_thresh seconds then the debug-printout triggers in
- * watchdog_timer_fn().
- */
- while (!kthread_should_stop()) {
- __touch_watchdog();
- schedule();
+ /* initialize timestamp */
+ watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);
+ __touch_watchdog();
+}
- if (kthread_should_stop())
- break;
+static void watchdog_disable(unsigned int cpu)
+{
+ struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
- set_current_state(TASK_INTERRUPTIBLE);
- }
- /*
- * Drop the policy/priority elevation during thread exit to avoid a
- * scheduling latency spike.
- */
- __set_current_state(TASK_RUNNING);
- sched_setscheduler(current, SCHED_NORMAL, ¶m);
- return 0;
+ watchdog_set_prio(SCHED_NORMAL, 0);
+ hrtimer_cancel(hrtimer);
+ /* disable the perf event */
+ watchdog_nmi_disable(cpu);
+}
+
+static int watchdog_should_run(unsigned int cpu)
+{
+ return __this_cpu_read(hrtimer_interrupts) !=
+ __this_cpu_read(soft_lockup_hrtimer_cnt);
}
+/*
+ * The watchdog thread function - touches the timestamp.
+ *
+ * It only runs once every get_sample_period() seconds (4 seconds by
+ * default) to reset the softlockup timestamp. If this gets delayed
+ * for more than 2*watchdog_thresh seconds then the debug-printout
+ * triggers in watchdog_timer_fn().
+ */
+static void watchdog(unsigned int cpu)
+{
+ __this_cpu_write(soft_lockup_hrtimer_cnt,
+ __this_cpu_read(hrtimer_interrupts));
+ __touch_watchdog();
+}
#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static int watchdog_nmi_enable(int cpu)
+static int watchdog_nmi_enable(unsigned int cpu)
{
struct perf_event_attr *wd_attr;
struct perf_event *event = per_cpu(watchdog_ev, cpu);
@@ -395,7 +419,6 @@ static int watchdog_nmi_enable(int cpu)
goto out_save;
}
-
/* vary the KERN level based on the returned errno */
if (PTR_ERR(event) == -EOPNOTSUPP)
pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
@@ -416,7 +439,7 @@ out:
return 0;
}
-static void watchdog_nmi_disable(int cpu)
+static void watchdog_nmi_disable(unsigned int cpu)
{
struct perf_event *event = per_cpu(watchdog_ev, cpu);
@@ -430,107 +453,35 @@ static void watchdog_nmi_disable(int cpu
return;
}
#else
-static int watchdog_nmi_enable(int cpu) { return 0; }
-static void watchdog_nmi_disable(int cpu) { return; }
+static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
+static void watchdog_nmi_disable(unsigned int cpu) { return; }
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
/* prepare/enable/disable routines */
-static void watchdog_prepare_cpu(int cpu)
-{
- struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
-
- WARN_ON(per_cpu(softlockup_watchdog, cpu));
- hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
- hrtimer->function = watchdog_timer_fn;
-}
-
-static int watchdog_enable(int cpu)
-{
- struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
- int err = 0;
-
- /* enable the perf event */
- err = watchdog_nmi_enable(cpu);
-
- /* Regardless of err above, fall through and start softlockup */
-
- /* create the watchdog thread */
- if (!p) {
- struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
- p = kthread_create_on_node(watchdog, NULL, cpu_to_node(cpu), "watchdog/%d", cpu);
- if (IS_ERR(p)) {
- pr_err("softlockup watchdog for %i failed\n", cpu);
- if (!err) {
- /* if hardlockup hasn't already set this */
- err = PTR_ERR(p);
- /* and disable the perf event */
- watchdog_nmi_disable(cpu);
- }
- goto out;
- }
- sched_setscheduler(p, SCHED_FIFO, ¶m);
- kthread_bind(p, cpu);
- per_cpu(watchdog_touch_ts, cpu) = 0;
- per_cpu(softlockup_watchdog, cpu) = p;
- wake_up_process(p);
- }
-
-out:
- return err;
-}
-
-static void watchdog_disable(int cpu)
-{
- struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
- struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
-
- /*
- * cancel the timer first to stop incrementing the stats
- * and waking up the kthread
- */
- hrtimer_cancel(hrtimer);
-
- /* disable the perf event */
- watchdog_nmi_disable(cpu);
-
- /* stop the watchdog thread */
- if (p) {
- per_cpu(softlockup_watchdog, cpu) = NULL;
- kthread_stop(p);
- }
-}
-
/* sysctl functions */
#ifdef CONFIG_SYSCTL
static void watchdog_enable_all_cpus(void)
{
- int cpu;
-
- watchdog_enabled = 0;
-
- for_each_online_cpu(cpu)
- if (!watchdog_enable(cpu))
- /* if any cpu succeeds, watchdog is considered
- enabled for the system */
- watchdog_enabled = 1;
-
- if (!watchdog_enabled)
- pr_err("failed to be enabled on some cpus\n");
+ unsigned int cpu;
+ if (watchdog_disabled) {
+ watchdog_disabled = 0;
+ for_each_online_cpu(cpu)
+ kthread_unpark(per_cpu(softlockup_watchdog, cpu));
+ }
}
static void watchdog_disable_all_cpus(void)
{
- int cpu;
-
- for_each_online_cpu(cpu)
- watchdog_disable(cpu);
+ unsigned int cpu;
- /* if all watchdogs are disabled, then they are disabled for the system */
- watchdog_enabled = 0;
+ if (!watchdog_disabled) {
+ watchdog_disabled = 1;
+ for_each_online_cpu(cpu)
+ kthread_park(per_cpu(softlockup_watchdog, cpu));
+ }
}
-
/*
* proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
*/
@@ -540,73 +491,36 @@ int proc_dowatchdog(struct ctl_table *ta
{
int ret;
+ if (watchdog_disabled < 0)
+ return -ENODEV;
+
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
if (ret || !write)
- goto out;
+ return ret;
if (watchdog_enabled && watchdog_thresh)
watchdog_enable_all_cpus();
else
watchdog_disable_all_cpus();
-out:
return ret;
}
#endif /* CONFIG_SYSCTL */
-
-/*
- * Create/destroy watchdog threads as CPUs come and go:
- */
-static int __cpuinit
-cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
-{
- int hotcpu = (unsigned long)hcpu;
-
- switch (action) {
- case CPU_UP_PREPARE:
- case CPU_UP_PREPARE_FROZEN:
- watchdog_prepare_cpu(hotcpu);
- break;
- case CPU_ONLINE:
- case CPU_ONLINE_FROZEN:
- if (watchdog_enabled)
- watchdog_enable(hotcpu);
- break;
-#ifdef CONFIG_HOTPLUG_CPU
- case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
- watchdog_disable(hotcpu);
- break;
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- watchdog_disable(hotcpu);
- break;
-#endif /* CONFIG_HOTPLUG_CPU */
- }
-
- /*
- * hardlockup and softlockup are not important enough
- * to block cpu bring up. Just always succeed and
- * rely on printk output to flag problems.
- */
- return NOTIFY_OK;
-}
-
-static struct notifier_block __cpuinitdata cpu_nfb = {
- .notifier_call = cpu_callback
+static struct smp_hotplug_thread watchdog_threads = {
+ .store = &softlockup_watchdog,
+ .thread_should_run = watchdog_should_run,
+ .thread_fn = watchdog,
+ .thread_comm = "watchdog/%u",
+ .setup = watchdog_enable,
+ .park = watchdog_disable,
+ .unpark = watchdog_enable,
};
void __init lockup_detector_init(void)
{
- void *cpu = (void *)(long)smp_processor_id();
- int err;
-
- err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
- WARN_ON(notifier_to_errno(err));
-
- cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
- register_cpu_notifier(&cpu_nfb);
-
- return;
+ if (smpboot_register_percpu_thread(&watchdog_threads)) {
+ pr_err("Failed to create watchdog threads, disabled\n");
+ watchdog_disabled = -ENODEV;
+ }
}
next prev parent reply other threads:[~2012-07-16 10:43 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-16 10:42 [Patch 0/7] Per cpu thread hotplug infrastructure - V3 Thomas Gleixner
2012-07-16 10:42 ` [Patch 1/7] rcu: Yield simpler Thomas Gleixner
2012-08-13 15:07 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2012-07-16 10:42 ` [Patch 3/7] smpboot: Provide infrastructure for percpu hotplug threads Thomas Gleixner
2012-07-21 9:26 ` Srivatsa S. Bhat
2012-07-21 18:01 ` Srivatsa S. Bhat
2012-07-21 17:12 ` Paul E. McKenney
2012-08-13 15:10 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2012-09-19 21:47 ` [Patch 3/7] " Sasha Levin
2012-10-12 1:39 ` Sasha Levin
2012-07-16 10:42 ` [Patch 2/7] kthread: Implement park/unpark facility Thomas Gleixner
2012-07-21 9:31 ` Srivatsa S. Bhat
2012-08-13 15:08 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2012-07-16 10:42 ` [Patch 4/7] softirq: Use hotplug thread infrastructure Thomas Gleixner
2012-07-21 17:21 ` Paul E. McKenney
2012-07-23 21:15 ` Paul E. McKenney
2012-07-25 14:21 ` JoonSoo Kim
2012-08-13 15:12 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2012-07-16 10:42 ` [Patch 6/7] rcu: Use smp_hotplug_thread facility for RCUs per-CPU kthread Thomas Gleixner
2012-07-16 16:59 ` Paul E. McKenney
2012-08-13 15:13 ` [tip:smp/hotplug] " tip-bot for Paul E. McKenney
2012-07-16 10:42 ` Thomas Gleixner [this message]
2012-08-13 15:13 ` [tip:smp/hotplug] watchdog: Use hotplug thread infrastructure tip-bot for Thomas Gleixner
2012-08-14 7:20 ` viresh kumar
2012-08-14 8:42 ` Thomas Gleixner
2012-07-16 10:42 ` [Patch 7/7] infiniband: ehca: " Thomas Gleixner
2012-07-17 0:27 ` Rusty Russell
2012-08-13 15:14 ` [tip:smp/hotplug] infiniband: Ehca: " tip-bot for Thomas Gleixner
2012-07-16 15:22 ` [Patch 0/7] Per cpu thread hotplug infrastructure - V3 Paul E. McKenney
2012-07-18 17:36 ` Srivatsa S. Bhat
2012-07-18 23:54 ` Paul E. McKenney
2012-07-20 13:17 ` Srivatsa S. Bhat
2012-07-20 14:35 ` Paul E. McKenney
2012-07-20 15:00 ` Srivatsa S. Bhat
2012-07-20 17:53 ` Paul E. McKenney
2012-07-20 18:28 ` Srivatsa S. Bhat
2012-07-25 12:25 ` Srivatsa S. Bhat
2012-07-25 14:25 ` JoonSoo Kim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120716103948.563736676@linutronix.de \
--to=tglx@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=namhyung@kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=rusty@rustcorp.com.au \
--cc=srivatsa.bhat@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).