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,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 2C61EC282CE for ; Wed, 22 May 2019 14:36:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F306420863 for ; Wed, 22 May 2019 14:36:24 +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="tRFD3Vc6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729215AbfEVOgY (ORCPT ); Wed, 22 May 2019 10:36:24 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49906 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728409AbfEVOgX (ORCPT ); Wed, 22 May 2019 10:36:23 -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=eq/H5RwjBNHhJrA53GEHBaRmVdHWZhwfz8MzKKlljQI=; b=tRFD3Vc6RzjVeFIxqOYQ9eCA9 lk5ZGKJR3T66Oe4phdSDDYC0jGhU2R+4DXYXdekh5ug7XUmrO7KpifaiarZ9Lc8KgP/JL/T0IMPzI WYTuBM/+Vt2q0PBHWl8vqzqitBgETewRNq8fGydAnurqDlBCbFlCi9FXtGQwoKTBjQJQ665IWkew9 zVb+dFiEE7Y6NhXHyAbq/QbzQwiJsCmLGKV9Z04LRsLmPT5AZLUYMbdzIxg01o5KmvCUvOAHELq1I erKxqd7bBWA2C7bjAYpWiEyeJwrDhfHyuEAVvetLz7YrAYs8GO8jFLn96IghYX7IOzcqiDurNHIyl tfSkLjWkA==; Received: from [31.161.185.207] (helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hTSLO-0003q5-NC; Wed, 22 May 2019 14:35:51 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 03CEC984E0B; Wed, 22 May 2019 16:35:45 +0200 (CEST) Date: Wed, 22 May 2019 16:35:45 +0200 From: Peter Zijlstra To: Viktor Rosendahl Cc: Steven Rostedt , Ingo Molnar , linux-kernel@vger.kernel.org, Joel Fernandes , "Rafael J . Wysocki" Subject: Re: [PATCH v4 1/4] ftrace: Implement fs notification for tracing_max_latency Message-ID: <20190522143545.GG16275@worktop.programming.kicks-ass.net> References: <20190521120142.186487e9@gandalf.local.home> <20190522003014.1359-1-viktor.rosendahl@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190522003014.1359-1-viktor.rosendahl@gmail.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, May 22, 2019 at 02:30:14AM +0200, Viktor Rosendahl wrote: > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 874c427742a9..440cd1a62722 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3374,6 +3374,7 @@ static void __sched notrace __schedule(bool preempt) > struct rq *rq; > int cpu; > > + trace_disable_fsnotify(); > cpu = smp_processor_id(); > rq = cpu_rq(cpu); > prev = rq->curr; > @@ -3449,6 +3450,7 @@ static void __sched notrace __schedule(bool preempt) > } > > balance_callback(rq); > + trace_enable_fsnotify(); > } > > void __noreturn do_task_dead(void) > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index 80940939b733..1a38bcdb3652 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -225,6 +225,7 @@ static void cpuidle_idle_call(void) > static void do_idle(void) > { > int cpu = smp_processor_id(); > + trace_disable_fsnotify(); > /* > * If the arch has a polling bit, we maintain an invariant: > * > @@ -284,6 +285,7 @@ static void do_idle(void) > smp_mb__after_atomic(); > > sched_ttwu_pending(); > + /* schedule_idle() will call trace_enable_fsnotify() */ > schedule_idle(); > > if (unlikely(klp_patch_pending(current))) I still hate this.. why are we doing this? We already have this stop_critical_timings() nonsense and are now adding more gunk. > +static DEFINE_PER_CPU(atomic_t, notify_disabled) = ATOMIC_INIT(0); > + atomic_set(&per_cpu(notify_disabled, cpu), 1); > + atomic_set(&per_cpu(notify_disabled, cpu), 0); > + if (!atomic_read(&per_cpu(notify_disabled, cpu))) That's just wrong on so many levels..