[tip:perf/core] perf intel-pt: Add brief documentation for PEBS via Intel PT

[tip-bot for Adrian Hunter <tipbot@zytor.com>]

Commit-ID:  243384dd25c8ea721c5c82a229eaf33cbd1bfd52
Gitweb:     https://git.kernel.org/tip/243384dd25c8ea721c5c82a229eaf33cbd1bfd52
Author:     Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Tue, 6 Aug 2019 11:46:06 +0300
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 14 Aug 2019 10:59:59 -0300

perf intel-pt: Add brief documentation for PEBS via Intel PT

Document how to select PEBS via Intel PT and how to display synthesized
PEBS samples.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190806084606.4021-8-alexander.shishkin@linux.intel.com
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
[ Update the example to use a group with intel_pt// as the group leader, as per Alex comment ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Documentation/intel-pt.txt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tools/perf/Documentation/intel-pt.txt b/tools/perf/Documentation/intel-pt.txt
index 50c5b60101bd..e0d9e7dd4f17 100644
--- a/tools/perf/Documentation/intel-pt.txt
+++ b/tools/perf/Documentation/intel-pt.txt
@@ -919,3 +919,18 @@ amended to take the number of elements as a parameter.
 
 Note there is currently no advantage to using Intel PT instead of LBR, but
 that may change in the future if greater use is made of the data.
+
+
+PEBS via Intel PT
+=================
+
+Some hardware has the feature to redirect PEBS records to the Intel PT trace.
+Recording is selected by using the aux-output config term e.g.
+
+	perf record -c 10000 -e '{intel_pt/branch=0/,cycles/aux-output/ppp}' uname
+
+Note that currently, software only supports redirecting at most one PEBS event.
+
+To display PEBS events from the Intel PT trace, use the itrace 'o' option e.g.
+
+	perf script --itrace=oe