From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756791AbbJVHoJ (ORCPT ); Thu, 22 Oct 2015 03:44:09 -0400 Received: from www.linutronix.de ([62.245.132.108]:58505 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752215AbbJVHoH (ORCPT ); Thu, 22 Oct 2015 03:44:07 -0400 Date: Thu, 22 Oct 2015 09:43:17 +0200 (CEST) From: Thomas Gleixner To: Yang Yingliang cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Hanjun Guo Subject: Re: Problem about CPU stalling in hrtimer_intterrupts() In-Reply-To: <56288585.40204@huawei.com> Message-ID: References: <56288585.40204@huawei.com> 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 22 Oct 2015, Yang Yingliang wrote: > I use the kernel-4.1.6 running on arm64. > My testcase is that it calls clock_settime and clock_adjtime alternately with > random params on each core. My system has 32 cores. > > I found the cpu stalling in hrtimer_intterrupts(). So I added some debug info > in hrtimer_intterrupts() and found that the while loop runs 1020437660 times > and takes 98761 jiffies(HZ=250). > > Some debug log is here: > ---start--- > Jan 01 00:03:32 Linux kernel: i:0 basenow.tv64:4809284991830 > hrtimer_get_softexpires_tv64(timer):4440120000000 ccpu0 > timer:ffffffdffdec6138, timer->function:ffffffc000129b84 > Jan 01 00:03:32 Linux kernel: i:0 basenow.tv64:4809284991830 > hrtimer_get_softexpires_tv64(timer):4440120000000 ccpu0 Something is rearming a timer over and over with expiry time in the past. Thanks, tglx