From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754637AbaHLHzy (ORCPT ); Tue, 12 Aug 2014 03:55:54 -0400 Received: from mail.skyhub.de ([78.46.96.112]:60571 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753469AbaHLHzx (ORCPT ); Tue, 12 Aug 2014 03:55:53 -0400 Date: Tue, 12 Aug 2014 09:55:41 +0200 From: Borislav Petkov To: Lan Tianyu Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, toshi.kani@hp.com, imammedo@redhat.com, mingo@kernel.org, prarit@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] X86/CPU: Avoid 100ms sleep for cpu offline during S3 Message-ID: <20140812075541.GB32061@pd.tnic> References: <1407142742-29202-1-git-send-email-tianyu.lan@intel.com> <1407828667-14316-1-git-send-email-tianyu.lan@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1407828667-14316-1-git-send-email-tianyu.lan@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 On Tue, Aug 12, 2014 at 03:31:06PM +0800, 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. ... and on an AMD laptop. > 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. > > Signed-off-by: Lan Tianyu Acked-by: Borislav Petkov -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. --