Messages in this thread Patch in this message | | | Date | Fri, 5 Jul 2013 00:30:11 +0200 | From | Stephane Eranian <> | Subject | [PATCH] perf: fix interrupt handler timing harness |
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This patch fixes a serious bug in:
commit 14c63f17b1fde5a575a28e96547a22b451c71fb5 Author: Dave Hansen <dave.hansen@linux.intel.com> Date: Fri Jun 21 08:51:36 2013 -0700
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 <eranian@google.com> ---
diff --git a/kernel/events/core.c b/kernel/events/core.c index 1db3af9..1833bc5 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;
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