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

srivatsabhat · rostedt · commit fc64e4ad80d4 · 2019-10-12T20:49:33.000-04:00
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: e7c15cd ("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>
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
@@ -256,6 +256,8 @@ static int get_sample(void)
 		/* Keep a running maximum ever recorded hardware latency */
 		if (sample > tr->max_latency)
 			tr->max_latency = sample;
+		if (outer_sample > tr->max_latency)
+			tr->max_latency = outer_sample;
 	}
 
 out:

Original file line number	Diff line number	Diff line change
`@@ -256,6 +256,8 @@ static int get_sample(void)`
`256`	`256`	`/* Keep a running maximum ever recorded hardware latency */`
`257`	`257`	`if (sample > tr->max_latency)`
`258`	`258`	`tr->max_latency = sample;`
	`259`	`+ if (outer_sample > tr->max_latency)`
	`260`	`+ tr->max_latency = outer_sample;`
`259`	`261`	`}`
`260`	`262`
`261`	`263`	`out:`