Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751994AbdGFIaY (ORCPT ); Thu, 6 Jul 2017 04:30:24 -0400 Received: from mga04.intel.com ([192.55.52.120]:49056 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbdGFIaV (ORCPT ); Thu, 6 Jul 2017 04:30:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,316,1496127600"; d="scan'208";a="121511236" Date: Thu, 6 Jul 2017 16:30:35 +0800 From: Chen Yu To: "Zheng, Lv" Cc: "Rafael J. Wysocki" , "Wysocki, Rafael J" , "Brown, Len" , Lv Zheng , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" Subject: Re: [PATCH 3/3] ACPI: EC: Change EC noirq tuning to be an optional behavior Message-ID: <20170706083035.GA2911@yu-desktop-1.sh.intel.com> References: <157972fa5572b0f0c157142ea151b8508e7640b4.1497418749.git.lv.zheng@intel.com> <1792284.us4mECpxNF@aspire.rjw.lan> <1AE640813FDE7649BE1B193DEA596E886CED9515@SHSMSX101.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1AE640813FDE7649BE1B193DEA596E886CED9515@SHSMSX101.ccr.corp.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2557 Lines: 57 Hi Lv, On Mon, Jul 03, 2017 at 01:15:26PM +0800, Zheng, Lv wrote: > Hi, Rafael > > > From: Rafael J. Wysocki [mailto:rjw@rjwysocki.net] > > Subject: Re: [PATCH 3/3] ACPI: EC: Change EC noirq tuning to be an optional behavior > > > > On Wednesday, June 14, 2017 01:59:24 PM Lv Zheng wrote: > > > According to the bug report, though the busy polling mode can make noirq > > > stages executed faster, it causes abnormal fan blowing in noirq stages. > > > > > > This patch prepares an option so that the automatic busy polling mode > > > switching for noirq stages can be enabled by who wants to tune it, not all > > > users. > > > Noticed that the new global option cannot be changed during noirq stages. > > > There is no need to lock its value changes to sync with polling mode > > > settings switches. > > > > > > For reporters and testers in the thread, as there are too many reporters > > > on the bug link, this patch only picks names from most active commenters. > > > Sorry for the neglet. > > > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=191181 > > > Reported-by: Tatsuyuki Ishi > > > Reported-by: Claudio Sacerdoti Coen > > > Tested-by: Nicolo' > > > Reported-by: Jens Axboe > > > Tested-by: Gjorgji Jankovski > > > Tested-by: Damjan Georgievski > > > Tested-by: Fernando Chaves > > > Signed-off-by: Lv Zheng > > > > First of all, this seems to be a fix for commit c3a696b6e8f8 (ACPI / EC: Use busy polling > > mode when GPE is not enabled), so there should be a Fixes: tag pointing to that > > one. > > > > Moreover, if that is just a performance optimization and not a matter of correctness, > > why don't we simply drop acpi_ec_enter/leave_noirq() entirely? > > > > What is going to break if we do that? > > Let me Cc Yu for justification. > I just added busy poll support for suspend/boot according to the root cause reported by him. > He should know the end user requirements better than me. > I remembered the original issue was reported against the slowness during suspend/resume due to the ec is running with GPE disabled, and falls into schedule_timeout() loop. If the busy polling mode is controlled by the boot options rather than acpi_ec_enter/leave_noirq(), then user should be noticed of the result that the cpu usage might be always higer if they enable the busy polling mode. Thanks, Yu > Thanks and best regards > Lv