From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755118Ab0DWCIG (ORCPT ); Thu, 22 Apr 2010 22:08:06 -0400 Received: from mga01.intel.com ([192.55.52.88]:11686 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755059Ab0DWCIE (ORCPT ); Thu, 22 Apr 2010 22:08:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,259,1270450800"; d="scan'208";a="791997871" Subject: Re: [RFC][PATCH 1/4] perf: core, add group scheduling transactional APIs From: Lin Ming To: Frederic Weisbecker Cc: Peter Zijlstra , Ingo Molnar , "eranian@gmail.com" , "Gary.Mohr@Bull.com" , Corey Ashford , "arjan@linux.intel.com" , "Zhang, Yanmin" , Paul Mackerras , "David S. Miller" , lkml In-Reply-To: <20100422173152.GA5600@nowhere> References: <1271922662.30535.107.camel@minggr.sh.intel.com> <20100422173152.GA5600@nowhere> Content-Type: text/plain Date: Fri, 23 Apr 2010 10:08:25 +0800 Message-Id: <1271988505.3412.20.camel@minggr.sh.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 (2.24.1-2.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-04-23 at 01:31 +0800, Frederic Weisbecker wrote: > 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 > > Reviewed-by: Peter Zijlstra > > Signed-off-by: Lin Ming > > --- > > 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. How about below changes? Thanks for review. diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index b16cfba..bba4c60 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -544,9 +544,21 @@ 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); + + /* + * group events scheduling is treated as a transaction, + * add group events as a whole and perform one schedulability test. + * If test fails, roll back the whole group + */ + + /* start group events transaction */ + void (*start_group_trans) (const struct pmu *pmu); + + /* stop group events transaction */ + void (*stop_group_trans) (const struct pmu *pmu); + + /* commit group events transaction */ + int (*commit_group_trans) (const struct pmu *pmu); }; /**