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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 22C42ECDE46 for ; Wed, 24 Oct 2018 18:13:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BBAB22082F for ; Wed, 24 Oct 2018 18:12:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBAB22082F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727330AbeJYCmB (ORCPT ); Wed, 24 Oct 2018 22:42:01 -0400 Received: from mga14.intel.com ([192.55.52.115]:50666 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726433AbeJYCmB (ORCPT ); Wed, 24 Oct 2018 22:42:01 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Oct 2018 11:12:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,421,1534834800"; d="scan'208";a="83849842" Received: from linux.intel.com ([10.54.29.200]) by orsmga007.jf.intel.com with ESMTP; 24 Oct 2018 11:12:57 -0700 Received: from [10.254.75.130] (kliang2-mobl1.ccr.corp.intel.com [10.254.75.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by linux.intel.com (Postfix) with ESMTPS id 862A45803FA; Wed, 24 Oct 2018 11:12:56 -0700 (PDT) Subject: Re: [PATCH 1/2] perf: Add munmap callback To: Arnaldo Carvalho de Melo , Andi Kleen Cc: Peter Zijlstra , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, bp@alien8.de, Stephane Eranian References: <20181024151116.30935-1-kan.liang@linux.intel.com> <20181024162334.GG6218@tassilo.jf.intel.com> <20181024163208.GC15106@kernel.org> From: "Liang, Kan" Message-ID: <18d5fcf4-84b2-806c-eb2c-787b96e0fb90@linux.intel.com> Date: Wed, 24 Oct 2018 14:12:54 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181024163208.GC15106@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed 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 On 10/24/2018 12:32 PM, Arnaldo Carvalho de Melo wrote: > Em Wed, Oct 24, 2018 at 09:23:34AM -0700, Andi Kleen escreveu: >>> +void perf_event_munmap(void) >>> +{ >>> + struct perf_cpu_context *cpuctx; >>> + unsigned long flags; >>> + struct pmu *pmu; >>> + >>> + local_irq_save(flags); >>> + list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) { >> >> Would be good have a fast path here that checks for the list being empty >> without disabling the interrupts. munmap can be somewhat hot. I think >> it's ok to make it slower with perf running, but we shouldn't impact >> it without perf. > > Right, look at how its counterpart, perf_event_mmap() works: > > void perf_event_mmap(struct vm_area_struct *vma) > { > struct perf_mmap_event mmap_event; > > if (!atomic_read(&nr_mmap_events)) > return; > > } > Thanks. I'll add the nr_mmap_events check in V2. Thanks, Kan