perf record: Add an option to force per-cpu mmaps

By default, when tasks are specified (i.e. -p, -t or -u options)
per-thread mmaps are created.

Add an option to override that and force per-cpu mmaps.

Further comments by peterz:

So this option allows -t/-p/-u to create one buffer per cpu and attach
all the various thread/process/user tasks' their counters to that one
buffer?

As opposed to the current state where each such counter would have its
own buffer.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1383313899-15987-7-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5 files changed, 14 insertions, 3 deletions

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 052f7c4dc00c..43b42c4f4a91 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -201,6 +201,12 @@ abort events and some memory events in precise mode on modern Intel CPUs.
 --transaction::
 Record transaction flags for transaction related events.
 
+--force-per-cpu::
+Force the use of per-cpu mmaps.  By default, when tasks are specified (i.e. -p,
+-t or -u options) per-thread mmaps are created.  This option overrides that and
+forces per-cpu mmaps.  A side-effect of that is that inheritance is
+automatically enabled.  Add the -i option also to disable inheritance.
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4d644fe2d5b7..7c8020a32784 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -888,6 +888,8 @@ const struct option record_options[] = {
                     "sample by weight (on special events only)"),
         OPT_BOOLEAN(0, "transaction", &record.opts.sample_transaction,
                     "sample transaction flags (special events only)"),
+        OPT_BOOLEAN(0, "force-per-cpu", &record.opts.target.force_per_cpu,
+                    "force the use of per-cpu mmaps"),
         OPT_END()
 };
 
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 5ce2ace2d6c1..bbc746aa5716 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -819,7 +819,9 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target)
         if (evlist->threads == NULL)
                 return -1;
 
-        if (target__has_task(target))
+        if (target->force_per_cpu)
+                evlist->cpus = cpu_map__new(target->cpu_list);
+        else if (target__has_task(target))
                 evlist->cpus = cpu_map__dummy_new();
         else if (!target__has_cpu(target) && !target->uses_mmap)
                 evlist->cpus = cpu_map__dummy_new();
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 18f7c188ff63..46dd4c2a41ce 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -645,7 +645,7 @@ void perf_evsel__config(struct perf_evsel *evsel,
                 }
         }
 
-        if (target__has_cpu(&opts->target))
+        if (target__has_cpu(&opts->target) || opts->target.force_per_cpu)
                 perf_evsel__set_sample_bit(evsel, CPU);
 
         if (opts->period)
@@ -653,7 +653,7 @@ void perf_evsel__config(struct perf_evsel *evsel,
 
         if (!perf_missing_features.sample_id_all &&
             (opts->sample_time || !opts->no_inherit ||
-             target__has_cpu(&opts->target)))
+             target__has_cpu(&opts->target) || opts->target.force_per_cpu))
                 perf_evsel__set_sample_bit(evsel, TIME);
 
         if (opts->raw_samples) {
diff --git a/tools/perf/util/target.h b/tools/perf/util/target.h
index 89bab7129de4..2d0c50690892 100644
--- a/tools/perf/util/target.h
+++ b/tools/perf/util/target.h
@@ -12,6 +12,7 @@ struct target {
         uid_t        uid;
         bool         system_wide;
         bool         uses_mmap;
+        bool         force_per_cpu;
 };
 
 enum target_errno {