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Commit 4eec42f3 authored by Mandeep Singh Baines's avatar Mandeep Singh Baines Committed by Ingo Molnar
Browse files

watchdog: Change the default timeout and configure nmi watchdog period based on watchdog_thresh 



Before the conversion of the NMI watchdog to perf event, the
watchdog timeout was 5 seconds. Now it is 60 seconds. For my
particular application, netbooks, 5 seconds was a better
timeout. With a short timeout, we catch faults earlier and are
able to send back a panic. With a 60 second timeout, the user is
unlikely to wait and will instead hit the power button, causing
us to lose the panic info.

This change configures the NMI period to watchdog_thresh and
sets the softlockup_thresh to watchdog_thresh * 2. In addition,
watchdog_thresh was reduced to 10 seconds as suggested by Ingo
Molnar.

Signed-off-by: default avatarMandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1306127423-3347-4-git-send-email-msb@chromium.org


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
LKML-Reference: <20110517071642.GF22305@elte.hu>
parent 586692a5

arch/x86/kernel/apic/hw_nmi.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -19,9 +19,9 @@ 
#include <linux/delay.h>

#include <linux/delay.h>





#ifdef CONFIG_HARDLOCKUP_DETECTOR

#ifdef CONFIG_HARDLOCKUP_DETECTOR

u64 hw_nmi_get_sample_period(void)

u64 hw_nmi_get_sample_period(int watchdog_thresh)

{

{

	return (u64)(cpu_khz) * 1000 * 60;

	return (u64)(cpu_khz) * 1000 * watchdog_thresh;

}

}

#endif

#endif

include/linux/nmi.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -45,7 +45,7 @@ static inline bool trigger_all_cpu_backtrace(void) 




#ifdef CONFIG_LOCKUP_DETECTOR

#ifdef CONFIG_LOCKUP_DETECTOR

int hw_nmi_is_cpu_stuck(struct pt_regs *);

int hw_nmi_is_cpu_stuck(struct pt_regs *);

u64 hw_nmi_get_sample_period(void);

u64 hw_nmi_get_sample_period(int watchdog_thresh);

extern int watchdog_enabled;

extern int watchdog_enabled;

extern int watchdog_thresh;

extern int watchdog_thresh;

struct ctl_table;

struct ctl_table;

kernel/watchdog.c

+15 −4
Original line number Original line Diff line number Diff line
@@ -28,7 +28,7 @@ 
#include <linux/perf_event.h>

#include <linux/perf_event.h>





int watchdog_enabled = 1;

int watchdog_enabled = 1;

int __read_mostly watchdog_thresh = 60;

int __read_mostly watchdog_thresh = 10;





static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);

static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);

static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);

static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
@@ -91,6 +91,17 @@ static int __init nosoftlockup_setup(char *str) 
__setup("nosoftlockup", nosoftlockup_setup);

__setup("nosoftlockup", nosoftlockup_setup);

/*  */

/*  */





/*

 * Hard-lockup warnings should be triggered after just a few seconds. Soft-

 * lockups can have false positives under extreme conditions. So we generally

 * want a higher threshold for soft lockups than for hard lockups. So we couple

 * the thresholds with a factor: we make the soft threshold twice the amount of

 * time the hard threshold is.

 */

static int get_softlockup_thresh()

{

	return watchdog_thresh * 2;

}





/*

/*

 * Returns seconds, approximately.  We don't need nanosecond

 * Returns seconds, approximately.  We don't need nanosecond
@@ -110,7 +121,7 @@ static unsigned long get_sample_period(void) 
	 * increment before the hardlockup detector generates

	 * increment before the hardlockup detector generates

	 * a warning

	 * a warning

	 */

	 */

	return watchdog_thresh * (NSEC_PER_SEC / 5);

	return get_softlockup_thresh() * (NSEC_PER_SEC / 5);

}

}





/* Commands for resetting the watchdog */

/* Commands for resetting the watchdog */
@@ -182,7 +193,7 @@ static int is_softlockup(unsigned long touch_ts) 
	unsigned long now = get_timestamp(smp_processor_id());

	unsigned long now = get_timestamp(smp_processor_id());





	/* Warn about unreasonable delays: */

	/* Warn about unreasonable delays: */

	if (time_after(now, touch_ts + watchdog_thresh))

	if (time_after(now, touch_ts + get_softlockup_thresh()))

		return now - touch_ts;

		return now - touch_ts;





	return 0;

	return 0;
@@ -359,7 +370,7 @@ static int watchdog_nmi_enable(int cpu) 




	/* Try to register using hardware perf events */

	/* Try to register using hardware perf events */

	wd_attr = &wd_hw_attr;

	wd_attr = &wd_hw_attr;

	wd_attr->sample_period = hw_nmi_get_sample_period();

	wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);

	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);

	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);

	if (!IS_ERR(event)) {

	if (!IS_ERR(event)) {

		printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");

		printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");