Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966412Ab2ERMzY (ORCPT ); Fri, 18 May 2012 08:55:24 -0400 Received: from s15943758.onlinehome-server.info ([217.160.130.188]:39484 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751343Ab2ERMzX (ORCPT ); Fri, 18 May 2012 08:55:23 -0400 Date: Fri, 18 May 2012 14:55:05 +0200 From: Borislav Petkov To: Ingo Molnar Cc: Peter Zijlstra , Frederic Weisbecker , Ingo Molnar , Steven Rostedt , LKML , Borislav Petkov Subject: Re: [PATCH 1/2] perf: Add persistent event facilities Message-ID: <20120518125505.GK20215@aftab.osrc.amd.com> References: <1332340496-21658-1-git-send-email-bp@amd64.org> <1332340496-21658-2-git-send-email-bp@amd64.org> <1337336040.573.12.camel@twins> <20120518110357.GH20215@aftab.osrc.amd.com> <1337340263.573.31.camel@twins> <20120518115957.GB19785@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120518115957.GB19785@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1841 Lines: 50 On Fri, May 18, 2012 at 01:59:57PM +0200, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > On Fri, 2012-05-18 at 13:03 +0200, Borislav Petkov wrote: > > > > - you allow an arbitrary place in debugfs; this might make finding > > > > them 'interesting'. Should we put them all in the same place? > > > > > > My take on this is that we want to be able to make the same events we > > > have now, persistent. Basically not trace for the duration of a child > > > process but in a process-agnostic way, system-wide. > > > > This would argue against per-task persistent events.. > > Yeah, 'persistency' is something that's per CPU at minimum. Yeah, forget the per-task thing - that's me not understanding the code fully. They need to be per CPU and "taskless." > > Note the plural there, it might be very desirable to allow > > multiple events into a single persistent buffer. > > very, very, very much so. One (per CPU) buffer, with many events > multiplexed into it. Which begs the other question: mce could use buffers which are RO - at least, I don't see a usecase where we want to delete entries from them - but other persistent events users might want to delete those events to free up the buffers. It is an interesting question how we handle that RO/RW thing? Maybe per event and do something of a kernel-side filtering which Peter didn't like in Robert's IBS stuff. Hmmm... -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach GM: Alberto Bozzo Reg: Dornach, Landkreis Muenchen HRB Nr. 43632 WEEE Registernr: 129 19551 -- 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/