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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 33783CA9EA0 for ; Fri, 18 Oct 2019 09:45:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1246D20820 for ; Fri, 18 Oct 2019 09:45:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388377AbfJRJpR (ORCPT ); Fri, 18 Oct 2019 05:45:17 -0400 Received: from mga07.intel.com ([134.134.136.100]:37926 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393449AbfJRJpR (ORCPT ); Fri, 18 Oct 2019 05:45:17 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Oct 2019 02:45:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,311,1566889200"; d="scan'208";a="195419784" Received: from linux.intel.com ([10.54.29.200]) by fmsmga008.fm.intel.com with ESMTP; 18 Oct 2019 02:45:16 -0700 Received: from [10.125.252.194] (abudanko-mobl.ccr.corp.intel.com [10.125.252.194]) by linux.intel.com (Postfix) with ESMTP id 169FA58048F; Fri, 18 Oct 2019 02:45:12 -0700 (PDT) Subject: [PATCH v3 4/4] perf/core,x86: synchronize PMU task contexts on optimized context switches From: Alexey Budankov To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , Ingo Molnar , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Andi Kleen , Kan Liang , Stephane Eranian , Ian Rogers , Song Liu , linux-kernel References: <0b20a07f-d074-d3da-7551-c9a4a94fe8e3@linux.intel.com> Organization: Intel Corp. Message-ID: Date: Fri, 18 Oct 2019 12:45:11 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <0b20a07f-d074-d3da-7551-c9a4a94fe8e3@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Install Intel specific PMU task context synchronization adapter and extend optimized context switch path with PMU specific task context synchronization to fix LBR callstack virtualization on context switches. Signed-off-by: Alexey Budankov --- arch/x86/events/intel/core.c | 7 +++++++ kernel/events/core.c | 9 +++++++++ 2 files changed, 16 insertions(+) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 43c966d1208e..7cfa658cce4b 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3819,6 +3819,12 @@ static void intel_pmu_sched_task(struct perf_event_context *ctx, intel_pmu_lbr_sched_task(ctx, sched_in); } +static void intel_pmu_sync_task_ctx(struct x86_perf_task_context *one, + struct x86_perf_task_context *another) +{ + intel_pmu_lbr_sync_task_ctx(one, another); +} + static int intel_pmu_check_period(struct perf_event *event, u64 value) { return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0; @@ -3954,6 +3960,7 @@ static __initconst const struct x86_pmu intel_pmu = { .guest_get_msrs = intel_guest_get_msrs, .sched_task = intel_pmu_sched_task, + .sync_task_ctx = intel_pmu_sync_task_ctx, .check_period = intel_pmu_check_period, diff --git a/kernel/events/core.c b/kernel/events/core.c index 2aad959e6def..3c7edd8454ef 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3204,11 +3204,20 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, raw_spin_lock(&ctx->lock); raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING); if (context_equiv(ctx, next_ctx)) { + struct pmu *pmu = ctx->pmu; + WRITE_ONCE(ctx->task, next); WRITE_ONCE(next_ctx->task, task); swap(ctx->task_ctx_data, next_ctx->task_ctx_data); + /* + * PMU specific parts of task perf context may require + * additional synchronization, at least for proper Intel + * LBR callstack data profiling; + */ + pmu->sync_task_ctx(ctx->task_ctx_data, + next_ctx->task_ctx_data); /* * RCU_INIT_POINTER here is safe because we've not * modified the ctx and the above modification of -- 2.20.1