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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2016-05-10 16:18:32 +0300
committerIngo Molnar <mingo@kernel.org>2016-05-12 14:45:59 +0200
commitab92b232ae05c382c3df0e3d6a5c6d16b639ac8c (patch)
tree93b9142829a9564b2bdef965fa0ceb7fc45e8b26
parent6d6f2833bfbf296101f9f085e10488aef2601ba5 (diff)
downloadleg-kernel-ab92b232ae05c382c3df0e3d6a5c6d16b639ac8c.tar.gz
perf/x86/intel/pt: Generate PMI in the STOP region as well
Currently, the PT driver always sets the PMI bit one region (page) before the STOP region so that we can wake up the consumer before we run out of room in the buffer and have to disable the event. However, we also need an interrupt in the last output region, so that we actually get to disable the event (if no more room from new data is available at that point), otherwise hardware just quietly refuses to start, but the event is scheduled in and we end up losing trace data till the event gets removed. For a cpu-wide event it is even worse since there may not be any re-scheduling at all and no chance for the ring buffer code to notice that its buffer is filled up and the event needs to be disabled (so that the consumer can re-enable it when it finishes reading the data out). In other words, all the trace data will be lost after the buffer gets filled up. This patch makes PT also generate a PMI when the last output region is full. Reported-by: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: vince@deater.net Link: http://lkml.kernel.org/r/1462886313-13660-2-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/events/intel/pt.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 09a77dbc73c9..7377814de30b 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -709,6 +709,7 @@ static int pt_buffer_reset_markers(struct pt_buffer *buf,
/* clear STOP and INT from current entry */
buf->topa_index[buf->stop_pos]->stop = 0;
+ buf->topa_index[buf->stop_pos]->intr = 0;
buf->topa_index[buf->intr_pos]->intr = 0;
/* how many pages till the STOP marker */
@@ -733,6 +734,7 @@ static int pt_buffer_reset_markers(struct pt_buffer *buf,
buf->intr_pos = idx;
buf->topa_index[buf->stop_pos]->stop = 1;
+ buf->topa_index[buf->stop_pos]->intr = 1;
buf->topa_index[buf->intr_pos]->intr = 1;
return 0;