Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: [PATCH 2/3] tracing/hwlat: Don't ignore outer-loop duration when
 calculating max_latency
From:   "Srivatsa S. Bhat" <srivatsa@csail.mit.edu>
To:     linux-kernel@vger.kernel.org, rostedt@goodmis.org, mingo@redhat.com
Cc:     amakhalov@vmware.com, akaher@vmware.com, anishs@vmware.com,
        bordoloih@vmware.com, srivatsab@vmware.com, srivatsa@csail.mit.edu
Date:   Thu, 10 Oct 2019 11:51:01 -0700
Message-ID: <157073345463.17189.18124025522664682811.stgit@srivatsa-ubuntu>
In-Reply-To: <157073343544.17189.13911783866738671133.stgit@srivatsa-ubuntu>
References: <157073343544.17189.13911783866738671133.stgit@srivatsa-ubuntu>
User-Agent: StGit/0.18
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>

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.

Fixes: e7c15cd8a113 ("tracing: Added hardware latency tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
---

 kernel/trace/trace_hwlat.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index a0251a7..862f4b0 100644
--- 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: