From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755146Ab0DWCLz (ORCPT ); Thu, 22 Apr 2010 22:11:55 -0400 Received: from mail-ww0-f46.google.com ([74.125.82.46]:45273 "EHLO mail-ww0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752740Ab0DWCLy (ORCPT ); Thu, 22 Apr 2010 22:11:54 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=LsyjlfTYsp/mdGylZipw+Efd+4B/YVk+rOUZLY3DKgNwmAz/qLug85OYMM6vV0uGBE C4gi4h8jc5uz6ylAPWvgGyRG4NAsrqtjkfFk1H3tpqpMaYkUq8dTUWxpQyokIedBHY8H hAcc2GNzhR2cex0JC8JMQm3IGoi3jHxPzQgXY= Date: Fri, 23 Apr 2010 04:12:01 +0200 From: Frederic Weisbecker To: Lin Ming 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 Subject: Re: [RFC][PATCH 1/4] perf: core, add group scheduling transactional APIs Message-ID: <20100423021159.GF5600@nowhere> References: <1271922662.30535.107.camel@minggr.sh.intel.com> <20100422173152.GA5600@nowhere> <1271988505.3412.20.camel@minggr.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1271988505.3412.20.camel@minggr.sh.intel.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 23, 2010 at 10:08:25AM +0800, Lin Ming wrote: > 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); > }; Looks good! Thanks.