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.hun...@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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
