From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932999AbaHEJbU (ORCPT ); Tue, 5 Aug 2014 05:31:20 -0400 Received: from mga09.intel.com ([134.134.136.24]:17604 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754975AbaHEJbS (ORCPT ); Tue, 5 Aug 2014 05:31:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,804,1400050800"; d="scan'208";a="553896436" Message-ID: <53E0A3D4.7020100@intel.com> Date: Tue, 05 Aug 2014 17:28:52 +0800 From: Lan Tianyu User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Borislav Petkov CC: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, toshi.kani@hp.com, imammedo@redhat.com, jan.kiszka@siemens.com, mingo@kernel.org, huawei.libin@huawei.com, prarit@redhat.com, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCH] X86/CPU: Avoid 100ms sleep for cpu offline during S3 References: <1407142742-29202-1-git-send-email-tianyu.lan@intel.com> <20140805084135.GB18234@pd.tnic> In-Reply-To: <20140805084135.GB18234@pd.tnic> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014年08月05日 16:41, Borislav Petkov wrote: > On Mon, Aug 04, 2014 at 04:59:02PM +0800, Lan Tianyu wrote: >> Some test result shows cpu offline consumes more than 100ms during S3. >> After some researchs, found native_cpu_die() would fall into 100ms >> sleep if cpu idle loop thread marked cpu state slower. 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. >> >> Signed-off-by: Lan Tianyu >> --- >> arch/x86/kernel/smpboot.c | 26 ++++++++++++++------------ >> 1 file changed, 14 insertions(+), 12 deletions(-) > > ... > >> @@ -1339,18 +1342,16 @@ int native_cpu_disable(void) >> void native_cpu_die(unsigned int cpu) >> { >> /* We don't do anything here: idle task is faking death itself. */ >> - unsigned int i; >> + wait_for_completion_timeout(&per_cpu(die_complete, cpu), >> + msecs_to_jiffies(1000)); > > One more thing peterz suggested. Just do: > > wait_for_completion_timeout(&per_cpu(die_complete, cpu), HZ); > > because HZ is the number of jiffies in a second. Which is what you want > here. > Yes, that looks better. I will update. -- Best regards Tianyu Lan