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Subject[tip:perf/urgent] perf record: Add an option to force per-cpu mmaps
Commit-ID:  539e6bb71e350541105e67e3d6c31392d9da25ef
Gitweb: http://git.kernel.org/tip/539e6bb71e350541105e67e3d6c31392d9da25ef
Author: Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Fri, 1 Nov 2013 15:51:34 +0200
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 14 Nov 2013 16:10:27 -0300

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>
---
tools/perf/Documentation/perf-record.txt | 6 ++++++
tools/perf/builtin-record.c | 2 ++
tools/perf/util/evlist.c | 4 +++-
tools/perf/util/evsel.c | 4 ++--
tools/perf/util/target.h | 1 +
5 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 052f7c4..43b42c4 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 4d644fe..7c8020a 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 5ce2ace..bbc746a 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 18f7c18..46dd4c2 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 89bab71..2d0c506 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 {

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