perf pmu: Auto-merge PMU events created by prefix or glob match

Auto-merge for these events was disabled when auto-merging of non-alias
events was disabled in commit 63ce844 (perf stat: Only auto-merge events
that are PMU aliases).

Non-merging of legacy events is preserved:

    $ perf stat -ag -e cache-misses,cache-misses sleep 1

     Performance counter stats for 'system wide':

                86,323      cache-misses
                86,323      cache-misses

           1.002623307 seconds time elapsed

But prefix or glob matching auto-merges the events created:

    $ perf stat -a -e l3cache/read-miss/ sleep 1

     Performance counter stats for 'system wide':

                   328      l3cache/read-miss/

           1.002627008 seconds time elapsed

    $ perf stat -a -e l3cache_0_[01]/read-miss/ sleep 1

     Performance counter stats for 'system wide':

                   172      l3cache/read-miss/

           1.002627008 seconds time elapsed

As with events created with aliases, auto-merging can be suppressed with
the --no-merge option:

    $ perf stat -a -e l3cache/read-miss/ --no-merge sleep 1

     Performance counter stats for 'system wide':

                    67      l3cache/read-miss/
                    67      l3cache/read-miss/
                    63      l3cache/read-miss/
                    60      l3cache/read-miss/

           1.002622192 seconds time elapsed

Signed-off-by: Agustin Vega-Frias <agustinv@codeaurora.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Timur Tabi <timur@codeaurora.org>
Cc: linux-arm-kernel@lists.infradead.org
Change-Id: I0a47eed54c05e1982ca964d743b37f50f60c508c
Link: http://lkml.kernel.org/r/1520345084-42646-4-git-send-email-agustinv@codeaurora.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 628026dbedc5..f15b306be183 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -267,11 +267,15 @@ taskset.
 --no-merge::
 Do not merge results from same PMUs.
 
-When multiple events are created from a single event alias, stat will,
-by default, aggregate the event counts and show the result in a single
-row. This option disables that behavior and shows the individual events
-and counts. Aliases are listed immediately after the Kernel PMU events
-by perf list.
+When multiple events are created from a single event specification,
+stat will, by default, aggregate the event counts and show the result
+in a single row. This option disables that behavior and shows
+the individual events and counts.
+
+Multiple events are created from a single event specification when:
+1. Prefix or glob matching is used for the PMU name.
+2. Aliases, which are listed immediately after the Kernel PMU events
+   by perf list, are used.
 
 --smi-cost::
 Measure SMI cost if msr/aperf/ and msr/smi/ events are supported.