From 96ca4028aca0638d0e11dcbfabc4283054072933 Mon Sep 17 00:00:00 2001 From: Don Zickus Date: Tue, 16 Feb 2010 17:02:25 -0500 Subject: [PATCH] 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 Signed-off-by: Don Zickus Cc: gorcunov@gmail.com Cc: aris@redhat.com Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker LKML-Reference: <1266357745-26671-1-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar --- kernel/nmi_watchdog.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/kernel/nmi_watchdog.c b/kernel/nmi_watchdog.c index 633b230c2319..3c75cbf3acb8 100644 --- a/kernel/nmi_watchdog.c +++ b/kernel/nmi_watchdog.c @@ -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; -- 2.45.2