This patch fixes a serious bug in:
commit 14c63f17b1fde5a575a28e96547a22b451c71fb5
Author: Dave Hansen <dave.han...@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 <eran...@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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