From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932957AbbFJTcO (ORCPT ); Wed, 10 Jun 2015 15:32:14 -0400 Received: from www.linutronix.de ([62.245.132.108]:53493 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754428AbbFJTcE (ORCPT ); Wed, 10 Jun 2015 15:32:04 -0400 Date: Wed, 10 Jun 2015 21:32:08 +0200 (CEST) From: Thomas Gleixner To: Steven Rostedt cc: Mike Galbraith , LKML , Peter Zijlstra , Ingo Molnar Subject: Re: RFC: futex_wait() can DoS the tick In-Reply-To: <20150610151551.3cfc616a@gandalf.local.home> Message-ID: References: <1433940278.6814.66.camel@gmail.com> <1433957421.6306.28.camel@gmail.com> <20150610151551.3cfc616a@gandalf.local.home> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Jun 2015, Steven Rostedt wrote: > On Wed, 10 Jun 2015 20:59:49 +0200 (CEST) > Thomas Gleixner wrote: > > > On Wed, 10 Jun 2015, Mike Galbraith wrote: > > > > > On Wed, 2015-06-10 at 17:12 +0200, Thomas Gleixner wrote: > > > > > > > Some more information about your symptoms in form of configuration, > > > > extra patches, kernel traces etc. would be appreciated. > > > > > > homer:~/tmp # perf record -C 3 -eirq:*,irq_vectors:local* -- sleep 10 > > I would recommend using trace-cmd especially if you add function > tracing, as it's made more for fast tracing. > > -- Steve > > > > [ perf record: Woken up 2 times to write data ] > > > [ perf record: Captured and wrote 1380.507 MB perf.data (19530595 samples) ] > > > homer:~/tmp # perf script | grep irq_vectors:local_timer > > > ksoftirqd/3 19 [003] 5586.564238: irq_vectors:local_timer_entry: vector=239 > > > ksoftirqd/3 19 [003] 5586.564239: irq_vectors:local_timer_exit: vector=239 > > > ksoftirqd/3 19 [003] 5586.568238: irq_vectors:local_timer_entry: vector=239 > > > ksoftirqd/3 19 [003] 5586.568239: irq_vectors:local_timer_exit: vector=239 > > > ksoftirqd/3 19 [003] 5586.632218: irq_vectors:local_timer_entry: vector=239 > > > > That gap is odd. Can you fire up the function tracer please? And please enable hrtimer events as well. Output of that cpu is good enough. Thanks, tglx