Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756877Ab2EGPoo (ORCPT ); Mon, 7 May 2012 11:44:44 -0400 Received: from tx2ehsobe004.messaging.microsoft.com ([65.55.88.14]:31008 "EHLO tx2outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754541Ab2EGPon (ORCPT ); Mon, 7 May 2012 11:44:43 -0400 X-SpamScore: -12 X-BigFish: VPS-12(zz936eK1432N98dKzz1202hzzz2dh668h839h944hd25h) X-Forefront-Antispam-Report: CIP:163.181.249.108;KIP:(null);UIP:(null);IPV:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-WSS-ID: 0M3NT2E-01-2IR-02 X-M-MSG: Date: Mon, 7 May 2012 17:44:12 +0200 From: Robert Richter To: Peter Zijlstra CC: Arnaldo Carvalho de Melo , Ingo Molnar , Stephane Eranian , Jiri Olsa , LKML Subject: Re: [PATCH 4/7] perf/x86-ibs: Add support for IBS pseudo events Message-ID: <20120507154412.GH18810@erda.amd.com> References: <1335983192-23731-1-git-send-email-robert.richter@amd.com> <1335983192-23731-5-git-send-email-robert.richter@amd.com> <1336395782.27020.37.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1336395782.27020.37.camel@laptop> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1746 Lines: 44 On 07.05.12 15:03:02, Peter Zijlstra wrote: > On Wed, 2012-05-02 at 20:26 +0200, Robert Richter wrote: > > +enum ibs_filter_type { > > + IBS_NO_FILTER = 0, > > + IBS_MATCH_FILTER = 1, > > + IBS_ANY_SET_FILTER = 2, > > + IBS_PSEUDO_EVENT = 0x0F, > > +}; > > I don't get how those pseudo events work, AFAIKT IBS_PSEUDO_EVENT causes > one to loose all events since it does have a filter set but fails the > filter and thus we skip the call to perf_event_overflow(). You periodically (fix clk cycles or number of micro-ops) trigger IBS samples and afterwards analyses the samples for certain filter rules (see rule description in pmu-ibs.c). > Furthermore, I think this filter stuff should accumulate the period so > that PERF_SAMPLE_PERIOD still works correctly and reflects the number of > counts since the last sample. Yes, simply dropping the sample is not enough. Have to check if the period is correctly maintained. > Also, what's the point of filtering in-kernel as opposed to doing all > this in userspace? Is the amount of data 'saved' significant enough? In-kernel filtering has drawbacks esp. if you want to handle multiple pseudo-events and also when post-processing a perf.data file. But for a proof-of-concept and a demonstration it was the easiest implementation since there is a lack of userland filtering. I guess I will look at how to implement this. -Robert -- Advanced Micro Devices, Inc. Operating System Research Center -- 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/