Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757067Ab1F1Kzv (ORCPT ); Tue, 28 Jun 2011 06:55:51 -0400 Received: from db3ehsobe006.messaging.microsoft.com ([213.199.154.144]:43976 "EHLO DB3EHSOBE006.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757181Ab1F1Kxo (ORCPT ); Tue, 28 Jun 2011 06:53:44 -0400 X-SpamScore: -12 X-BigFish: VPS-12(zz4015L1432N98dKzz1202hzz8275bh8275dhz32i668h839h61h) X-Spam-TCS-SCL: 0:0 X-Forefront-Antispam-Report: CIP:163.181.249.108;KIP:(null);UIP:(null);IPVD:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-WSS-ID: 0LNHY9D-01-1X0-02 X-M-MSG: Date: Tue, 28 Jun 2011 12:53:35 +0200 From: Robert Richter To: Peter Zijlstra CC: "linux-tip-commits@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "hpa@zytor.com" , "mingo@redhat.com" , "francis.moro@gmail.com" , "tglx@linutronix.de" , "mingo@elte.hu" Subject: Re: [tip:perf/core] perf: Ignore non-sampling overflows Message-ID: <20110628105335.GA17199@erda.amd.com> References:

MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: 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: 2470 Lines: 79 On 26.11.10 10:04:56, tip-bot for Peter Zijlstra wrote: > Commit-ID: 963988262c3c8f4234f64a0dde59446a295e07bb > Gitweb: http://git.kernel.org/tip/963988262c3c8f4234f64a0dde59446a295e07bb > Author: Peter Zijlstra > AuthorDate: Wed, 24 Nov 2010 18:55:29 +0100 > Committer: Ingo Molnar > CommitDate: Fri, 26 Nov 2010 15:14:55 +0100 > > perf: Ignore non-sampling overflows > > Some arch implementations call perf_event_overflow() by 'accident', > ignore this. > > Reported-by: Francis Moreau > Signed-off-by: Peter Zijlstra > LKML-Reference: > Signed-off-by: Ingo Molnar > --- > kernel/perf_event.c | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > index 98c5549..af1e63f 100644 > --- a/kernel/perf_event.c > +++ b/kernel/perf_event.c > @@ -4240,6 +4240,13 @@ static int __perf_event_overflow(struct perf_event *event, int nmi, > struct hw_perf_event *hwc = &event->hw; > int ret = 0; > > + /* > + * Non-sampling counters might still use the PMI to fold short > + * hardware counters, ignore those. > + */ > + if (unlikely(!is_sampling_event(event))) > + return 0; > + Peter, do you remember the background of this change. This check silently drops data of non-sampling events. I want to use perf_event_overflow() to write to the buffer and want to modify the check, but don't see which 'accidentally' interrupts may occur that must be ignored. I was thinking of modifying the check to something like: static inline bool is_sampling_event(struct perf_event *event) { return event->attr.sample_type != 0; } or if (unlikely(!is_sampling_event(event) && !event->attr.sample_type)) ... Thanks, -Robert > if (!throttle) { > hwc->interrupts++; > } else { > -- > 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/ > -- 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/