From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754080AbaJ1WqL (ORCPT ); Tue, 28 Oct 2014 18:46:11 -0400 Received: from mga02.intel.com ([134.134.136.20]:35477 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750858AbaJ1WqI (ORCPT ); Tue, 28 Oct 2014 18:46:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,805,1406617200"; d="scan'208";a="627243937" Message-ID: <54501CAB.8040503@linux.intel.com> Date: Wed, 29 Oct 2014 06:46:03 +0800 From: "Li, Aubrey" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Peter Zijlstra CC: "Rafael J. Wysocki" , "Brown, Len" , "alan@linux.intel.com" , Thomas Gleixner , "H. Peter Anvin" , linux-kernel@vger.kernel.org, "linux-pm@vger.kernel.org >> Linux PM list" Subject: Re: [RFC/PATCH] PM / Sleep: Timer quiesce in freeze state References: <5446787E.60202@linux.intel.com> <20141024153656.GM12706@worktop.programming.kicks-ass.net> <544DE5CF.9040501@linux.intel.com> <20141027072816.GD10501@worktop.programming.kicks-ass.net> <544F1C50.8010505@linux.intel.com> <20141028082900.GP3337@twins.programming.kicks-ass.net> In-Reply-To: <20141028082900.GP3337@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/10/28 16:29, Peter Zijlstra wrote: > On Tue, Oct 28, 2014 at 12:32:16PM +0800, Li, Aubrey wrote: >> On 2014/10/27 15:28, Peter Zijlstra wrote: >>> On Mon, Oct 27, 2014 at 02:27:27PM +0800, Li, Aubrey wrote: >>>>> Now I suppose the problem is with cpu_pause() which needs IPIs to >>>>> complete? Do we really need cpuidle_pause() there? >>>>> cpuidle_uninstall_handlers() seems like a daft thing to call just about >>>>> there. >>>> >>>> Please check the log of 8651f97bd951d0bb1c10fa24e3fa3455193f3548. >>>> Rafael should know more this question than me. >>> >>> That changelog explains its complete bollocks to do it here. We _want_ >>> to enter and/or remain in deep idle states. >> >> cpuidle_resume() will be called at the end of dpm_resume_noirq(). So we >> still are able to enter deep idle states after resume. > > cpuidle_resume is absolute crap, as is cpuidle_suspend for that matter > -- in this case. > > The only reason we needed cpuidle_suspend is because some BIOS shat its > pants when some CPUs were in higher C states while trying to do the S3 > thing. We're not going to use S states or BIOS calls _at_all_, so no > point in kicking CPUs out of their deep C states. We already kicked CPUs out of their deep C states in dpm_suspend_noirq(). We pause cpuidle in dpm_suspend_noirq() and resume cpuidle in dpm_resume_noirq(), so currently we can't enter deep c-state during S states. That's an intention for some buggy BIOS. However, for freeze state, there is another intention that we want always to enter the *deepest* c-state every time we enter freeze. So we need cpuidle_resume() to make sure we have deep cstate in freeze. So back to your question in another email, > I think you can simply remove them altogether, they're nonsense. We need them to resume cpuidle in freeze. Thanks, -Aubrey > > Read that changelog you referred me to again. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >