| 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: tracing/hwlat: Report total time spent in all NMIs during the sample |
| |
| From: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> |
| |
| commit 98dc19c11470ee6048aba723d77079ad2cda8a52 upstream. |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/trace/trace_hwlat.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- 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) |
