From e5302920da9ef23f9d19d4e9ac85704cc25bee7a Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Fri, 5 Jul 2013 00:30:11 +0200 Subject: [PATCH] perf: Fix interrupt handler timing harness This patch fixes a serious bug in: 14c63f17b1fd perf: Drop sample rate when sampling is too slow There was an misunderstanding on the API of the do_div() macro. It returns the remainder of the division and this was not what the function expected leading to disabling the interrupt latency watchdog. This patch also remove a duplicate assignment in perf_sample_event_took(). Signed-off-by: Stephane Eranian Cc: peterz@infradead.org Cc: dave.hansen@linux.intel.com Cc: ak@linux.intel.com Cc: jolsa@redhat.com Link: http://lkml.kernel.org/r/20130704223010.GA30625@quad Signed-off-by: Ingo Molnar --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 1db3af933704..1833bc5a84a7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -182,7 +182,7 @@ void update_perf_cpu_limits(void) u64 tmp = perf_sample_period_ns; tmp *= sysctl_perf_cpu_time_max_percent; - tmp = do_div(tmp, 100); + do_div(tmp, 100); atomic_set(&perf_sample_allowed_ns, tmp); } @@ -232,7 +232,7 @@ DEFINE_PER_CPU(u64, running_sample_length); void perf_sample_event_took(u64 sample_len_ns) { u64 avg_local_sample_len; - u64 local_samples_len = __get_cpu_var(running_sample_length); + u64 local_samples_len; if (atomic_read(&perf_sample_allowed_ns) == 0) return; -- 2.20.1