From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750978AbbCZEB3 (ORCPT ); Thu, 26 Mar 2015 00:01:29 -0400 Received: from e19.ny.us.ibm.com ([129.33.205.209]:54407 "EHLO e19.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750708AbbCZEB0 (ORCPT ); Thu, 26 Mar 2015 00:01:26 -0400 Date: Wed, 25 Mar 2015 21:00:24 -0700 From: Sukadev Bhattiprolu To: Peter Zijlstra Cc: Michael Ellerman , Paul Mackerras , dev@codyps.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 1/4] perf: Add 'flags' parameter to pmu txn interfaces Message-ID: <20150326040024.GB31846@us.ibm.com> References: <1425458108-3341-1-git-send-email-sukadev@linux.vnet.ibm.com> <1425458108-3341-2-git-send-email-sukadev@linux.vnet.ibm.com> <20150317064745.GL2896@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150317064745.GL2896@worktop.programming.kicks-ass.net> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15032604-0013-0000-0000-00000040AD6C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra [peterz@infradead.org] wrote: | On Wed, Mar 04, 2015 at 12:35:05AM -0800, Sukadev Bhattiprolu wrote: | > In addition to using the transaction interface to schedule events | > on a PMU, we will use it to also read a group of counters at once. | > Accordingly, add a flags parameter to the transaction interfaces. | > The flags indicate wheether the transaction is to add events to | > the PMU (PERF_PMU_TXN_ADD) or to read the events PERF_PMU_TXN_READ. | > | > Based on input from Peter Zijlstra. | > | > Signed-off-by: Sukadev Bhattiprolu | > --- | > arch/powerpc/perf/core-book3s.c | 15 ++++++++++++--- | > arch/x86/kernel/cpu/perf_event.c | 15 ++++++++++++--- | > include/linux/perf_event.h | 14 +++++++++++--- | > kernel/events/core.c | 26 +++++++++++++++----------- | > 4 files changed, 50 insertions(+), 20 deletions(-) | | s390 and sparc also implement the txn. Yes, I have fixed that now. Was mostly exploring the basic txn interface. | | # git grep "\.start_txn" | arch/powerpc/perf/core-book3s.c: .start_txn = power_pmu_start_txn, | arch/s390/kernel/perf_cpum_cf.c: .start_txn = cpumf_pmu_start_txn, | arch/sparc/kernel/perf_event.c: .start_txn = sparc_pmu_start_txn, | arch/x86/kernel/cpu/perf_event.c: .start_txn = x86_pmu_start_txn, | | Also; you add the flag to all 3 calls; does it make sense to only pass | it to the first and save the txn type in the txn state itself? We could | add PERF_EVENT_TXN_READ for this.. We could do that. The one small downside I see with passing the txn flag only ot ->start_txn() is that checks like this become more complicated, even in PMUs that don't care about the TXN_READ transactions. @@ -1619,8 +1622,11 @@ static void x86_pmu_start_txn(struct pmu *pmu) * Clear the flag and pmu::enable() will perform the * schedulability test. */ -static void x86_pmu_cancel_txn(struct pmu *pmu) +static void x86_pmu_cancel_txn(struct pmu *pmu, int flags) { + if (flags & ~PERF_PMU_TXN_ADD) + return; + The ->start_txn will need to save the transaction type in the architecture's 'cpuhw' and check/clear in ->commit_txn() and ->clear_txn() - right ? Sukadev