From 98dc19c11470ee6048aba723d77079ad2cda8a52 Mon Sep 17 00:00:00 2001
From: "Srivatsa S. Bhat (VMware)" <srivatsa@csail.mit.edu>
Date: Thu, 10 Oct 2019 11:50:46 -0700
Subject: [PATCH] tracing/hwlat: Report total time spent in all NMIs during the
sample
nmi_total_ts is supposed to record the total time spent in *all* NMIs
that occur on the given CPU during the (active portion of the)
sampling window. However, the code seems to be overwriting this
variable for each NMI, thereby only recording the time spent in the
most recent NMI. Fix it by accumulating the duration instead.
Link: http://lkml.kernel.org/r/157073343544.17189.13911783866738671133.stgit@srivatsa-ubuntu
Fixes: 7b2c86250122 ("tracing: Add NMI tracing in hwlat detector")
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>
---
kernel/trace/trace_hwlat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index fa95139445b28..a0251a78807db 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -150,7 +150,7 @@ void trace_hwlat_callback(bool enter)
if (enter)
nmi_ts_start = time_get();
else
- nmi_total_ts = time_get() - nmi_ts_start;
+ nmi_total_ts += time_get() - nmi_ts_start;
}
if (enter)
--
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