perf tools: Add an option to multiplex counters in a single channel

Add an option to multiplex counters output in the channel of
the group leader, ie: the first counter opened:

	-M --multiplex

The effect is better serialized samples. This is especially
useful for tracepoint samples that need to be well serialized
for their post-processing.

Also make use of this option in 'perf sched'.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 99a12fe..79f99db 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -48,6 +48,7 @@ static int                    call_graph                      = 0;
 static int                     inherit_stat                    = 0;
 static int                     no_samples                      = 0;
 static int                     sample_address                  = 0;
+static int                     multiplex                       = 0;
 
 static long                    samples;
 static struct timeval          last_read;
@@ -485,6 +486,9 @@ try_again:
                exit(-1);
        }
 
+       if (multiplex && fd[nr_cpu][counter] != group_fd)
+               ioctl(fd[nr_cpu][counter], PERF_COUNTER_IOC_SET_OUTPUT, group_fd);
+
        ioctl(fd[nr_cpu][counter], PERF_COUNTER_IOC_ENABLE);
 }
 
@@ -681,6 +685,8 @@ static const struct option options[] = {
                    "Sample addresses"),
        OPT_BOOLEAN('n', "no-samples", &no_samples,
                    "don't sample"),
+       OPT_BOOLEAN('M', "multiplex", &multiplex,
+                   "multiplex counter output in a single channel"),
        OPT_END()
 };
 

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 8db0fd2..686af63 100644 (file)
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1660,6 +1660,8 @@ static const char *record_args[] = {
        "record",
        "-a",
        "-R",
+       "-M",
+       "-g",
        "-c", "1",
        "-e", "sched:sched_switch:r",
        "-e", "sched:sched_stat_wait:r",