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Commit 586692a5 authored by Mandeep Singh Baines's avatar Mandeep Singh Baines Committed by Ingo Molnar
Browse files

watchdog: Disable watchdog when thresh is zero 



This restores the previous behavior of softlock_thresh.

Currently, setting watchdog_thresh to zero causes the watchdog
kthreads to consume a lot of CPU.

In addition, the logic of proc_dowatchdog_thresh and
proc_dowatchdog_enabled has been factored into proc_dowatchdog.

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/1306127423-3347-3-git-send-email-msb@chromium.org


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
LKML-Reference: <20110517071018.GE22305@elte.hu>
parent e04ab2bc

include/linux/nmi.h

+3 −2
Original line number Original line Diff line number Diff line
@@ -47,8 +47,9 @@ static inline bool trigger_all_cpu_backtrace(void) 
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(void);

extern int watchdog_enabled;

extern int watchdog_enabled;

extern int watchdog_thresh;

struct ctl_table;

struct ctl_table;

extern int proc_dowatchdog_enabled(struct ctl_table *, int ,

extern int proc_dowatchdog(struct ctl_table *, int ,

			   void __user *, size_t *, loff_t *);

			   void __user *, size_t *, loff_t *);

#endif

#endif

include/linux/sched.h

+0 −1
Original line number Original line Diff line number Diff line
@@ -315,7 +315,6 @@ extern int proc_dowatchdog_thresh(struct ctl_table *table, int write, 
				  void __user *buffer,

				  void __user *buffer,

				  size_t *lenp, loff_t *ppos);

				  size_t *lenp, loff_t *ppos);

extern unsigned int  softlockup_panic;

extern unsigned int  softlockup_panic;

extern int softlockup_thresh;

void lockup_detector_init(void);

void lockup_detector_init(void);

#else

#else

static inline void touch_softlockup_watchdog(void)

static inline void touch_softlockup_watchdog(void)

kernel/sysctl.c

+8 −4
Original line number Original line Diff line number Diff line
@@ -730,14 +730,16 @@ static struct ctl_table kern_table[] = { 
		.data           = &watchdog_enabled,

		.data           = &watchdog_enabled,

		.maxlen         = sizeof (int),

		.maxlen         = sizeof (int),

		.mode           = 0644,

		.mode           = 0644,

		.proc_handler   = proc_dowatchdog_enabled,

		.proc_handler   = proc_dowatchdog,

		.extra1		= &zero,

		.extra2		= &one,

	},

	},

	{

	{

		.procname	= "watchdog_thresh",

		.procname	= "watchdog_thresh",

		.data		= &softlockup_thresh,

		.data		= &watchdog_thresh,

		.maxlen		= sizeof(int),

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.mode		= 0644,

		.proc_handler	= proc_dowatchdog_thresh,

		.proc_handler	= proc_dowatchdog,

		.extra1		= &neg_one,

		.extra1		= &neg_one,

		.extra2		= &sixty,

		.extra2		= &sixty,

	},

	},
@@ -755,7 +757,9 @@ static struct ctl_table kern_table[] = { 
		.data           = &watchdog_enabled,

		.data           = &watchdog_enabled,

		.maxlen         = sizeof (int),

		.maxlen         = sizeof (int),

		.mode           = 0644,

		.mode           = 0644,

		.proc_handler   = proc_dowatchdog_enabled,

		.proc_handler   = proc_dowatchdog,

		.extra1		= &zero,

		.extra2		= &one,

	},

	},

#endif

#endif

#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)

#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)

kernel/watchdog.c

+9 −16
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 softlockup_thresh = 60;

int __read_mostly watchdog_thresh = 60;





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);
@@ -105,12 +105,12 @@ static unsigned long get_timestamp(int this_cpu) 
static unsigned long get_sample_period(void)

static unsigned long get_sample_period(void)

{

{

	/*

	/*

	 * convert softlockup_thresh from seconds to ns

	 * convert watchdog_thresh from seconds to ns

	 * the divide by 5 is to give hrtimer 5 chances to

	 * the divide by 5 is to give hrtimer 5 chances to

	 * increment before the hardlockup detector generates

	 * increment before the hardlockup detector generates

	 * a warning

	 * a warning

	 */

	 */

	return softlockup_thresh * (NSEC_PER_SEC / 5);

	return watchdog_thresh * (NSEC_PER_SEC / 5);

}

}





/* Commands for resetting the watchdog */

/* Commands for resetting the watchdog */
@@ -182,7 +182,7 @@ 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 + softlockup_thresh))

	if (time_after(now, touch_ts + watchdog_thresh))

		return now - touch_ts;

		return now - touch_ts;





	return 0;

	return 0;
@@ -501,19 +501,19 @@ static void watchdog_disable_all_cpus(void) 
/* sysctl functions */

/* sysctl functions */

#ifdef CONFIG_SYSCTL

#ifdef CONFIG_SYSCTL

/*

/*

 * proc handler for /proc/sys/kernel/nmi_watchdog

 * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh

 */

 */





int proc_dowatchdog_enabled(struct ctl_table *table, int write,

int proc_dowatchdog(struct ctl_table *table, int write,

		     void __user *buffer, size_t *length, loff_t *ppos)

		    void __user *buffer, size_t *lenp, loff_t *ppos)

{

{

	int ret;

	int ret;





	ret = proc_dointvec(table, write, buffer, length, ppos);

	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

	if (ret || !write)

	if (ret || !write)

		goto out;

		goto out;





	if (watchdog_enabled)

	if (watchdog_enabled && watchdog_thresh)

		watchdog_enable_all_cpus();

		watchdog_enable_all_cpus();

	else

	else

		watchdog_disable_all_cpus();

		watchdog_disable_all_cpus();
@@ -521,13 +521,6 @@ int proc_dowatchdog_enabled(struct ctl_table *table, int write, 
out:

out:

	return ret;

	return ret;

}

}



int proc_dowatchdog_thresh(struct ctl_table *table, int write,

			     void __user *buffer,

			     size_t *lenp, loff_t *ppos)

{

	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);

}

#endif /* CONFIG_SYSCTL */

#endif /* CONFIG_SYSCTL */