From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757828Ab0CKMrg (ORCPT ); Thu, 11 Mar 2010 07:47:36 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:52514 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757774Ab0CKMrf (ORCPT ); Thu, 11 Mar 2010 07:47:35 -0500 Date: Thu, 11 Mar 2010 13:47:16 +0100 From: Ingo Molnar To: Peter Zijlstra Cc: Robert Richter , LKML , oprofile-list Subject: Re: [PATCH 0/9] oprofile, perf, x86: introduce new functions to reserve perfctrs Message-ID: <20100311124716.GH31354@elte.hu> References: <1267716131-17908-1-git-send-email-robert.richter@amd.com> <1267725559.25158.208.camel@laptop> <1268308081.5037.14.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1268308081.5037.14.camel@laptop> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Peter Zijlstra wrote: > On Thu, 2010-03-04 at 18:59 +0100, Peter Zijlstra wrote: > > On Thu, 2010-03-04 at 16:22 +0100, Robert Richter wrote: > > > This patch set improves the perfctr reservation code. New functions > > > are available to reserve a counter by its index only. It is no longer > > > necessary to allocate both msrs of a counter which also improves the > > > code and makes it easier. > > > > > > For oprofile a handler is implemented that returns an error now if a > > > counter is already reserved by a different subsystem such as perf or > > > watchdog. Before, oprofile silently ignored that counter. Finally the > > > new reservation functions can be used to allocate special parts of the > > > pmu such as IBS, which is necessary to use IBS with perf too. > > > > > > The patches are available in the oprofile tree: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile.git core > > > > > > If there are no objections, I suggest to merge it into the > > > tip/perf/core too, maybe after pending patches went in. If there are > > > already conflicts, I will do the merge for this. > > > > Right, so cleaning up that reservation code is nice, but wouldn't it be > > much nicer to simply do away with all that and make everything use the > > (low level) perf code? > > Alternatively, could we maybe further simplify this reservation into: > > int reserve_pmu(void); > void release_pmu(void); > > And not bother with anything finer grained. Yeah, that looks quite a bit simpler. It's all about making it easier to live with legacies anyway - all modern facilities will use perf events to access the PMU. Ingo