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tracing/hwlat: Don't ignore outer-loop duration when calculating max_latency

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max_latency is intended to record the maximum ever observed hardware
latency, which may occur in either part of the loop (inner/outer). So
we need to also consider the outer-loop sample when updating
max_latency.

Link: http://lkml.kernel.org/r/157073345463.17189.18124025522664682811.stgit@srivatsa-ubuntu

Fixes: e7c15cd8a1 ("tracing: Added hardware latency tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Srivatsa S. Bhat (VMware) 2019-10-10 11:51:01 -07:00 committed by Steven Rostedt (VMware)
parent 98dc19c114
commit fc64e4ad80
1 changed files with 2 additions and 0 deletions
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2
kernel/trace/trace_hwlat.c
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@ -256,6 +256,8 @@ static int get_sample(void)
/* Keep a running maximum ever recorded hardware latency */ /* Keep a running maximum ever recorded hardware latency */
if (sample > tr->max_latency) if (sample > tr->max_latency)
tr->max_latency = sample; tr->max_latency = sample;
if (outer_sample > tr->max_latency)
tr->max_latency = outer_sample;
} }
out: out: