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Commit 96ca4028 authored by Don Zickus's avatar Don Zickus Committed by Ingo Molnar
Browse files

nmi_watchdog: Properly configure for software events 



Paul Mackerras brought up a good point that when fallbacking to
software events, I may have been lucky in my configuration.

Modified the code to explicit provide a new configuration for
software events.

Suggested-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1266357745-26671-1-git-send-email-dzickus@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6081b6cd

kernel/nmi_watchdog.c

+18 −5
Original line number Diff line number Diff line
@@ -61,7 +61,7 @@ static int __init setup_nmi_watchdog(char *str) 
}

__setup("nmi_watchdog=", setup_nmi_watchdog);



struct perf_event_attr wd_attr = {

struct perf_event_attr wd_hw_attr = {

	.type = PERF_TYPE_HARDWARE,

	.config = PERF_COUNT_HW_CPU_CYCLES,

	.size = sizeof(struct perf_event_attr),
@@ -69,6 +69,14 @@ struct perf_event_attr wd_attr = { 
	.disabled = 1,

};



struct perf_event_attr wd_sw_attr = {

	.type = PERF_TYPE_SOFTWARE,

	.config = PERF_COUNT_SW_CPU_CLOCK,

	.size = sizeof(struct perf_event_attr),

	.pinned = 1,

	.disabled = 1,

};



void wd_overflow(struct perf_event *event, int nmi,

		 struct perf_sample_data *data,

		 struct pt_regs *regs)
@@ -105,6 +113,7 @@ void wd_overflow(struct perf_event *event, int nmi, 
static int enable_nmi_watchdog(int cpu)

{

	struct perf_event *event;

	struct perf_event_attr *wd_attr;



	event = per_cpu(nmi_watchdog_ev, cpu);

	if (event && event->state > PERF_EVENT_STATE_OFF)
@@ -112,11 +121,15 @@ static int enable_nmi_watchdog(int cpu) 


	if (event == NULL) {

		/* Try to register using hardware perf events first */

		wd_attr.sample_period = hw_nmi_get_sample_period();

		event = perf_event_create_kernel_counter(&wd_attr, cpu, -1, wd_overflow);

		wd_attr = &wd_hw_attr;

		wd_attr->sample_period = hw_nmi_get_sample_period();

		event = perf_event_create_kernel_counter(wd_attr, cpu, -1, wd_overflow);

		if (IS_ERR(event)) {

			wd_attr.type = PERF_TYPE_SOFTWARE;

			event = perf_event_create_kernel_counter(&wd_attr, cpu, -1, wd_overflow);

			/* hardware doesn't exist or not supported, fallback to software events */

			printk("nmi_watchdog: hardware not available, trying software events\n");

			wd_attr = &wd_sw_attr;

			wd_attr->sample_period = NSEC_PER_SEC;

			event = perf_event_create_kernel_counter(wd_attr, cpu, -1, wd_overflow);

			if (IS_ERR(event)) {

				printk(KERN_ERR "nmi watchdog failed to create perf event on %i: %p\n", cpu, event);

				return -1;