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authorCarsten Emde <C.Emde@osadl.org>2012-07-11 22:05:19 +0000
committerSteven Rostedt <rostedt@goodmis.org>2013-04-30 23:02:01 -0400
commit93270d58378d38975200d057eb0d240871d0b0f0 (patch)
tree572c653ebb70388580b662da0d57b0e7c93d7fdd
parent2c09855bfba131263cb615876dc020d1f9a8c490 (diff)
Latency histograms: Detect another yet overlooked sharedprio condition
While waiting for an RT process to be woken up, the previous process may go to wait and switch to another one with the same priority which then becomes current. This condition was not correctly recognized and led to erroneously high latency recordings during periods of low CPU load. This patch correctly marks such latencies as sharedprio and prevents them from being recorded as actual system latency. Signed-off-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/latency_hist.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/trace/latency_hist.c b/kernel/trace/latency_hist.c
index d514eefd5ac8..6a4c8694c55a 100644
--- a/kernel/trace/latency_hist.c
+++ b/kernel/trace/latency_hist.c
@@ -935,6 +935,9 @@ static notrace void probe_wakeup_latency_hist_stop(void *v,
goto out;
}
+ if (current->prio == cpu_wakeup_task->prio)
+ per_cpu(wakeup_sharedprio, cpu) = 1;
+
/*
* The task we are waiting for is about to be switched to.
* Calculate latency and store it in histogram.