From 98dc19c11470ee6048aba723d77079ad2cda8a52 Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat (VMware)" Date: Thu, 10 Oct 2019 11:50:46 -0700 Subject: 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) Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_hwlat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/trace_hwlat.c') diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index fa95139445b2..a0251a78807d 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) -- cgit v1.2.3 From fc64e4ad80d4b72efce116f87b3174f0b7196f8e Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat (VMware)" Date: Thu, 10 Oct 2019 11:51:01 -0700 Subject: tracing/hwlat: Don't ignore outer-loop duration when calculating max_latency 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: e7c15cd8a113 ("tracing: Added hardware latency tracer") Cc: stable@vger.kernel.org Signed-off-by: Srivatsa S. Bhat (VMware) Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_hwlat.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/trace/trace_hwlat.c') diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index a0251a78807d..862f4b0139fc 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: -- cgit v1.2.3