Messages in this thread | | | Date | Thu, 22 Apr 2010 19:31:55 +0200 | From | Frederic Weisbecker <> | Subject | Re: [RFC][PATCH 1/4] perf: core, add group scheduling transactional APIs |
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On Thu, Apr 22, 2010 at 03:51:02PM +0800, Lin Ming wrote: > Add group scheduling transactional APIs to struct pmu. > These APIs will be implemented in arch code, based on Peter's idea as > below. > > > the idea behind hw_perf_group_sched_in() is to not perform > > schedulability tests on each event in the group, but to add the group > as > > a whole and then perform one test. > > > > Of course, when that test fails, you'll have to roll-back the whole > > group again. > > > > So start_txn (or a better name) would simply toggle a flag in the pmu > > implementation that will make pmu::enable() not perform the > > schedulablilty test. > > > > Then commit_txn() will perform the schedulability test (so note the > > method has to have a !void return value, my mistake in the earlier > > email). > > > > This will allow us to use the regular > > kernel/perf_event.c::group_sched_in() and all the rollback code. > > Currently each hw_perf_group_sched_in() implementation duplicates all > > the rolllback code (with various bugs). > > > Reviewed-by: Stephane Eranian <eranian@google.com> > Reviewed-by: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Lin Ming <ming.m.lin@intel.com> > --- > include/linux/perf_event.h | 8 +++++--- > kernel/perf_event.c | 29 ++++++++++++++++------------- > 2 files changed, 21 insertions(+), 16 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index ace31fb..b16cfba 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -532,6 +532,8 @@ struct hw_perf_event { > > struct perf_event; > > +#define PERF_EVENT_TRAN_STARTED 1 > + > /** > * struct pmu - generic performance monitoring unit > */ > @@ -542,6 +544,9 @@ struct pmu { > void (*stop) (struct perf_event *event); > void (*read) (struct perf_event *event); > void (*unthrottle) (struct perf_event *event); > + void (*start_txn) (const struct pmu *pmu); > + void (*stop_txn) (const struct pmu *pmu); > + int (*commit_txn) (const struct pmu *pmu);
Please add a few comments that briefly explain what these *_txn callbacks are supposed to mean.
Unless txn is an acronym that most kernel developers are used to.
Thanks.
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