From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752533AbaIXNA0 (ORCPT ); Wed, 24 Sep 2014 09:00:26 -0400 Received: from mail-wi0-f173.google.com ([209.85.212.173]:58322 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751209AbaIXNAY (ORCPT ); Wed, 24 Sep 2014 09:00:24 -0400 Date: Wed, 24 Sep 2014 15:00:19 +0200 From: Ingo Molnar To: Lan Tianyu Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, toshi.kani@hp.com, imammedo@redhat.com, bp@alien8.de, prarit@redhat.com, Peter Zijlstra , srostedt@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [Resend PATCH V2] X86/CPU: Avoid 100ms sleep for cpu offline during S3 Message-ID: <20140924130019.GA3277@gmail.com> References: <1409039025-32310-1-git-send-email-tianyu.lan@intel.com> <54211EB6.3020306@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54211EB6.3020306@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Lan Tianyu wrote: > On 2014年08月26日 15:43, Lan Tianyu wrote: > > With some bad kernel configures, cpu offline consumes more than 100ms > > during S3. This because native_cpu_die() would fall into 100ms > > sleep when cpu idle loop thread marked cpu state to DEAD slower. It's > > timing related issue. What native_cpu_die() does is that poll cpu > > state and wait for 100ms if cpu state hasn't been marked to DEAD. > > The 100ms sleep doesn't make sense. To avoid such long sleep, this > > patch is to add struct completion to each cpu, wait for the completion > > in the native_cpu_die() and wakeup the completion when the cpu state is > > marked to DEAD. > > > > Tested on the Intel Xeon server with 48 cores, Ivbridge and Haswell laptops. > > the times of cpu offline on these machines are reduced from more than 100ms > > to less than 5ms. The system suspend time reduces 2.3s on the servers. > > > > Borislav and Prarit also helped to test the patch on an AMD machine and > > a few systems of various sizes and configurations (multi-socket, > > single-socket, no hyper threading, etc.). No issues seen. > > > > Acked-by: Borislav Petkov > > Tested-by: Prarit Bhargava > > Signed-off-by: Lan Tianyu > > --- > > arch/x86/kernel/smpboot.c | 23 +++++++++++------------ > > 1 file changed, 11 insertions(+), 12 deletions(-) > > > > Hi HPA, Ingo, Thomas & Peter Z: > Is this patch ok for you? Nice patch! I cleaned up a few small details and will push it out if it passes testing. Thanks, Ingo