Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757366Ab0GAQWZ (ORCPT ); Thu, 1 Jul 2010 12:22:25 -0400 Received: from s15228384.onlinehome-server.info ([87.106.30.177]:35334 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757299Ab0GAQWX (ORCPT ); Thu, 1 Jul 2010 12:22:23 -0400 Date: Thu, 1 Jul 2010 18:24:24 +0200 From: Borislav Petkov To: Frederic Weisbecker Cc: Peter Zijlstra , Arnaldo Carvalho de Melo , Steven Rostedt , Ingo Molnar , LKML Subject: Re: [PATCH 03/21] perf_events: Add a helper to search for an event in a context Message-ID: <20100701162424.GI17823@aftab> References: <1277992175-19821-1-git-send-email-bp@amd64.org> <1277992175-19821-4-git-send-email-bp@amd64.org> <1277992805.1917.142.camel@laptop> <20100701141352.GA17823@aftab> <20100701161133.GE10616@nowhere> <1278000765.1917.220.camel@laptop> <20100701161448.GF10616@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100701161448.GF10616@nowhere> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 43 From: Frederic Weisbecker Date: Thu, Jul 01, 2010 at 12:14:50PM -0400 Hi Frederic, > On Thu, Jul 01, 2010 at 06:12:45PM +0200, Peter Zijlstra wrote: > > On Thu, 2010-07-01 at 18:11 +0200, Frederic Weisbecker wrote: > > > I suspect we need another syscall that can list all the persistent events > > > with a unique id and the attrs that follow. > > > > > > So you get a unique id for all of them and you can create an fd on top > > > of this id by using a PERF_FLAG_REQUEST_PERSISTENT and this id put in > > > attr.config. > > > > Isn't that what filesystems were invented for? > > > The problem is when you create a persistent event, you lose the fd. > So you need to retrieve it somehow. actually the idea is to decouple those from the fd alltogether and provide specific file_operations in debugfs and such, as Peter suggested. Which sounds much more sane to me especially since, at least in the MCE case, all the entities that register into that event need to see the same samples (and read the same buffers etc). And let's try not to read too much into those persistent events - it may just as well be that we need them only for MCEs and nothing else :) -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/