Messages in this thread Patch in this message | | | Date | Tue, 05 Nov 2013 15:09:30 +0200 | From | Adrian Hunter <> | Subject | Re: [PATCH V3 06/11] perf record: Add an option to force per-cpu mmaps |
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On 05/11/13 11:42, Jiri Olsa wrote: > On Tue, Nov 05, 2013 at 10:28:38AM +0200, Adrian Hunter wrote: >> On 04/11/13 17:29, Jiri Olsa wrote: >>> On Fri, Nov 01, 2013 at 03:51:34PM +0200, Adrian Hunter wrote: >>>> 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. >>>> >>>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.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 f10ab63..2ea6685 100644 >>>> --- a/tools/perf/Documentation/perf-record.txt >>>> +++ b/tools/perf/Documentation/perf-record.txt >>>> @@ -189,6 +189,12 @@ 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. >>> >>> I recently sent out patch that actually force perf cpu mmaps for -p,-t,-u >>> http://marc.info/?l=linux-kernel&m=138332119912433&w=2 >>> >>> Is there a reason why would you want to keep single >>> mmap (in record command) and cut yourself from inherited >>> events? >> >> Not sure I understand the question. >> >> perf supports having a single context for a thread. That is a >> feature. You seem to be removing perf tools support for it. >> >> I image a case where the user has hundreds of CPUs but just >> wants to record one thread. Currently -t does that. i.e. >> one file descriptor and one mmap saving megabytes of memory. >> >> Another advantage of per-thread mmaps is that you do not >> need to sample time (nor cpu), because the events are recorded >> in order. >> >> I was adding a feature. Users can choose per-cpu mmaps if >> they want. > > right, I haven't considered the hundreds CPU machine.. I just > saw that it disables inherited events in my test ;-) maybe we > could mentioned that somewhere, because it's not clear
How about this:
From: Adrian Hunter <adrian.hunter@intel.com>
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.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> --- tools/perf/Documentation/perf-record.txt | 15 +++++++++++++++ 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, 23 insertions(+), 3 deletions(-)
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 052f7c4..5d5cbed 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -53,14 +53,20 @@ OPTIONS -p:: --pid=:: Record events on existing process ID (comma separated list). + Note this causes the use of per-thread mmaps which prevents + inheritance. This can be overridden by --force-per-cpu. -t:: --tid=:: Record events on existing thread ID (comma separated list). + Note this causes the use of per-thread mmaps which prevents + inheritance. This can be overridden by --force-per-cpu. -u:: --uid=:: Record events in threads owned by uid. Name or number. + Note this causes the use of per-thread mmaps which prevents + inheritance. This can be overridden by --force-per-cpu. -r:: --realtime=:: @@ -81,6 +87,9 @@ OPTIONS -i:: --no-inherit:: Child tasks do not inherit counters. + Note that inheritance is not possible when events are recorded + with per-thread mmaps e.g. -p, -t or -u options. + -F:: --freq=:: Profile at this frequency. @@ -201,6 +210,12 @@ 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 8b45fce..6b6f5d9 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -889,6 +889,8 @@ 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 1c173cc..b3183d5 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -805,7 +805,9 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, if (evlist->threads == NULL) return -1; - if (perf_target__has_task(target)) + if (target->force_per_cpu) + evlist->cpus = cpu_map__new(target->cpu_list); + else if (perf_target__has_task(target)) evlist->cpus = cpu_map__dummy_new(); else if (!perf_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 5280820..080cc55 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 (perf_target__has_cpu(&opts->target)) + if (perf_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 || - perf_target__has_cpu(&opts->target))) + perf_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 a4be857..6d7efbd 100644 --- a/tools/perf/util/target.h +++ b/tools/perf/util/target.h @@ -12,6 +12,7 @@ struct perf_target { uid_t uid; bool system_wide; bool uses_mmap; + bool force_per_cpu; }; enum perf_target_errno { -- 1.7.11.7
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