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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: Paul Mackerras <paulus@samba.org>
Signed-off-by: Don 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Don Zickus 2010-02-16 17:02:25 -05:00 committed by Ingo Molnar
parent 6081b6cd97
commit 96ca4028ac
1 changed files with 18 additions and 5 deletions
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23
kernel/nmi_watchdog.c
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@ -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;