From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9689C32751 for ; Wed, 31 Jul 2019 16:50:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7E3B9208E3 for ; Wed, 31 Jul 2019 16:50:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qYliFr2P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730434AbfGaQuT (ORCPT ); Wed, 31 Jul 2019 12:50:19 -0400 Received: from merlin.infradead.org ([205.233.59.134]:43844 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726514AbfGaQuS (ORCPT ); Wed, 31 Jul 2019 12:50:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=M16IcJbVtcK6s+BiMRNJ1Hm7ZaYNlZKt9eZO5hx7aH0=; b=qYliFr2PO+2EqS/YmFoapRgRU bfiGCCwTZTob1I1SBoNS3RTHiJoPE8PgwOm6qcjOhy+hR5h+C56s8A9mC/0HfcaKdQ80jiDBW90uc HC+2IL7HPtCY2WQQT0uUvfVV2bVxKJ1lo+n/fBd8tIlAAMPseBDJXfuZEfGSF/Hq3ifjbbDOktTBL Qstol6QixMVw27cHOtJhIIHutuPEX8RjqnLkhgATeV0uOJ1S2TWJ7fwa0Dy1DMI8FNnBwOPdh9IwV al92sgMQdy6nP5TkaaN2MC+uhEFkLhzLoju9wYW9Q9mhFRCGInKSmjQNycuSqsGvCJl7MdbD8KpgE seJPwYesw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hsrns-0005TD-C5; Wed, 31 Jul 2019 16:50:16 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CEB982029F4C9; Wed, 31 Jul 2019 18:50:14 +0200 (CEST) Date: Wed, 31 Jul 2019 18:50:14 +0200 From: Peter Zijlstra To: Alexander Shishkin Cc: Arnaldo Carvalho de Melo , Ingo Molnar , linux-kernel@vger.kernel.org, kan.liang@linux.intel.com Subject: Re: [PATCH v3 2/7] perf/x86/intel: Support PEBS output to PT Message-ID: <20190731165014.GY31381@hirez.programming.kicks-ass.net> References: <20190731143041.64678-1-alexander.shishkin@linux.intel.com> <20190731143041.64678-3-alexander.shishkin@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190731143041.64678-3-alexander.shishkin@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 31, 2019 at 05:30:36PM +0300, Alexander Shishkin wrote: > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > index cfe256ca76df..6cf2a7ba822a 100644 > --- a/arch/x86/events/core.c > +++ b/arch/x86/events/core.c > @@ -1006,6 +1006,28 @@ static int collect_events(struct cpu_hw_events *cpuc, struct perf_event *leader, > /* current number of events already accepted */ > n = cpuc->n_events; > > + if (!cpuc->is_fake && leader->attr.precise_ip) { > + if (!n) > + cpuc->pebs_output = 0; I think this can go wobbly if we add a !pebs event first. That is, in that case '!n && !precise_ip' and we'll not reset the output state. > + > + /* > + * For PEBS->PT, if !aux_event, the group leader (PT) went > + * away, the group was broken down and this singleton event > + * can't schedule any more. > + */ > + if (WARN_ON_ONCE(is_pebs_pt(leader) && !leader->aux_event)) > + return -EINVAL; > + > + /* > + * pebs_output: 0: no PEBS so far, 1: PT, 2: DS > + */ > + if (cpuc->pebs_output && > + cpuc->pebs_output != is_pebs_pt(leader) + 1) > + return -EINVAL; > + > + cpuc->pebs_output = is_pebs_pt(leader) + 1; > + } > + > if (is_x86_event(leader)) { > if (n >= max_count) > return -EINVAL;