From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752784AbdLSUKI (ORCPT ); Tue, 19 Dec 2017 15:10:08 -0500 Received: from mga07.intel.com ([134.134.136.100]:3396 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751799AbdLSUKH (ORCPT ); Tue, 19 Dec 2017 15:10:07 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,428,1508828400"; d="scan'208";a="13677578" Subject: Re: [PATCH 4/4] perf/x86/intel: drain PEBS buffer in event read To: Peter Zijlstra Cc: mingo@redhat.com, acme@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, jolsa@redhat.com, eranian@google.com, ak@linux.intel.com References: <1513596891-12362-1-git-send-email-kan.liang@linux.intel.com> <1513596891-12362-5-git-send-email-kan.liang@linux.intel.com> <20171219190214.zaqhmpz2rv2a5pgl@hirez.programming.kicks-ass.net> From: "Liang, Kan" Message-ID: Date: Tue, 19 Dec 2017 15:10:04 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20171219190214.zaqhmpz2rv2a5pgl@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/19/2017 2:02 PM, Peter Zijlstra wrote: > On Mon, Dec 18, 2017 at 03:34:51AM -0800, kan.liang@linux.intel.com wrote: >> --- a/arch/x86/events/intel/ds.c >> +++ b/arch/x86/events/intel/ds.c >> @@ -926,6 +926,16 @@ void intel_pmu_pebs_del(struct perf_event *event) >> pebs_update_state(needed_cb, cpuc, event->ctx->pmu); >> } >> >> +void intel_pmu_pebs_read(struct perf_event *event) >> +{ >> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); >> + >> + if (pebs_needs_sched_cb(cpuc)) >> + return intel_pmu_drain_pebs_buffer(); >> + >> + x86_perf_event_update(event, 0, 0); >> +} > > This is completely broken.. what if @event isn't a pebs event, but we > do have an auto-reloading pebs event configured? > precise_ip will be checked before intel_pmu_pebs_read is called. So @event must be a pebs event. @@ -2060,6 +2060,14 @@ static void intel_pmu_del_event(struct perf_event *event) intel_pmu_pebs_del(event); } +static void intel_pmu_read_event(struct perf_event *event) +{ + if (event->attr.precise_ip) + return intel_pmu_pebs_read(event); + + x86_perf_event_update(event, 0, 0); +}