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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 2F7E6C04AB6 for ; Tue, 28 May 2019 13:32:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5F9220883 for ; Tue, 28 May 2019 13:32:39 +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="jYZJixTt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727521AbfE1Ncj (ORCPT ); Tue, 28 May 2019 09:32:39 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:43528 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726620AbfE1Nci (ORCPT ); Tue, 28 May 2019 09:32:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=gyDEltUy8Mkp5tNzv09VqhaOmTEcIorOyMwFp/rum1s=; b=jYZJixTtaT+g13+zPNmjkuMXi /+zlQr1UgFTCDju2uPbOIWr9uuW+kwX4H+rfvXloRl87RJHAH0/ZVmUe8LOvsrYpD9qTthNH0oeu4 1mLK8vsahxIFUYe5Q/Vw7eLT8+LOfdEdRNDfahJBrde5b+UvizDuPgTbLzwUXfg0YrfgWVTQxpAw2 U/PCN4aGDM+d/7G83tEhscSJWeRvLXwSYqw3IzZhcTueFeXKcsEmzf0QlaCfMqHzFVFZuvURAYYow G7f5r5jB2zKg+GTbl1daD3Py56KfIC8rD/lrwIdfX0mP1Feg50MCgKGlUjICB+CNjAY7lRT9RUSyx yAtIBUTrQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hVcDR-0005te-QD; Tue, 28 May 2019 13:32:33 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2C2552074C650; Tue, 28 May 2019 15:32:32 +0200 (CEST) Date: Tue, 28 May 2019 15:32:32 +0200 From: Peter Zijlstra To: kan.liang@linux.intel.com Cc: acme@kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, jolsa@kernel.org, eranian@google.com, alexander.shishkin@linux.intel.com, ak@linux.intel.com Subject: Re: [PATCH 4/9] perf/x86/intel: Support hardware TopDown metrics Message-ID: <20190528133232.GU2650@hirez.programming.kicks-ass.net> References: <20190521214055.31060-1-kan.liang@linux.intel.com> <20190521214055.31060-5-kan.liang@linux.intel.com> <20190528125615.GW2606@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190528125615.GW2606@hirez.programming.kicks-ass.net> 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 Tue, May 28, 2019 at 02:56:15PM +0200, Peter Zijlstra wrote: > On Tue, May 21, 2019 at 02:40:50PM -0700, kan.liang@linux.intel.com wrote: > > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > > index e9075d57853d..07ecfe75f0e6 100644 > > --- a/arch/x86/events/core.c > > +++ b/arch/x86/events/core.c > > @@ -91,16 +91,20 @@ u64 x86_perf_event_update(struct perf_event *event) > > new_raw_count) != prev_raw_count) > > goto again; AFAICT, you don't actually need that cmpxchg loop for the metric crud. > > > > - /* > > - * Now we have the new raw value and have updated the prev > > - * timestamp already. We can now calculate the elapsed delta > > - * (event-)time and add that to the generic event. > > - * > > - * Careful, not all hw sign-extends above the physical width > > - * of the count. > > - */ > > - delta = (new_raw_count << shift) - (prev_raw_count << shift); > > - delta >>= shift; > > + if (unlikely(hwc->flags & PERF_X86_EVENT_UPDATE)) > > + delta = x86_pmu.metric_update_event(event, new_raw_count); > > + else { > > + /* > > + * Now we have the new raw value and have updated the prev > > + * timestamp already. We can now calculate the elapsed delta > > + * (event-)time and add that to the generic event. > > + * > > + * Careful, not all hw sign-extends above the physical width > > + * of the count. > > + */ > > + delta = (new_raw_count << shift) - (prev_raw_count << shift); > > + delta >>= shift; > > + } > > > > local64_add(delta, &event->count); > > local64_sub(delta, &hwc->period_left); > > > @@ -1186,6 +1194,9 @@ int x86_perf_event_set_period(struct perf_event *event) > > if (idx == INTEL_PMC_IDX_FIXED_BTS) > > return 0; > > > > + if (x86_pmu.set_period && x86_pmu.set_period(event)) > > + goto update_userpage; > > + > > /* > > * If we are way outside a reasonable range then just skip forward: > > */ > > @@ -1234,6 +1245,7 @@ int x86_perf_event_set_period(struct perf_event *event) > > (u64)(-left) & x86_pmu.cntval_mask); > > } > > > > +update_userpage: > > perf_event_update_userpage(event); > > > > return ret; > > > *groan*.... that's pretty terrible.