Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753869AbaKMCxY (ORCPT ); Wed, 12 Nov 2014 21:53:24 -0500 Received: from mga01.intel.com ([192.55.52.88]:61931 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753603AbaKMCxX (ORCPT ); Wed, 12 Nov 2014 21:53:23 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="415778701" From: "Zheng, Lv" To: "Rafael J. Wysocki" CC: "Wysocki, Rafael J" , "Brown, Len" , Lv Zheng , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "Andi Kleen (ak@linux.intel.com)" Subject: RE: [PATCH 5/6] ACPI/EC: Cleanup QR_SC command processing by adding a kernel thread to poll EC events. Thread-Topic: [PATCH 5/6] ACPI/EC: Cleanup QR_SC command processing by adding a kernel thread to poll EC events. Thread-Index: AQHP/hNuclXJFrB3lkaCapiXtYP3B5xd1baw//+DeYCAAIOIIA== Date: Thu, 13 Nov 2014 02:52:03 +0000 Message-ID: <1AE640813FDE7649BE1B193DEA596E88026A0737@SHSMSX101.ccr.corp.intel.com> References: <2277351.09XTT17U9b@vostro.rjw.lan> <1AE640813FDE7649BE1B193DEA596E88026A0706@SHSMSX101.ccr.corp.intel.com> <1961414.bGx3EdA0yT@vostro.rjw.lan> In-Reply-To: <1961414.bGx3EdA0yT@vostro.rjw.lan> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id sAD2rTBO021145 Hi, Rafael > From: Rafael J. Wysocki [mailto:rjw@rjwysocki.net] > Sent: Thursday, November 13, 2014 10:59 AM > > On Thursday, November 13, 2014 02:31:08 AM Zheng, Lv wrote: > > Hi, Rafael > > > > > From: Rafael J. Wysocki [mailto:rjw@rjwysocki.net] > > > Sent: Wednesday, November 12, 2014 9:17 AM > > [cut] > > > > > + > > > > +static int ec_create_event_poller(struct acpi_ec *ec) > > > > +{ > > > > + struct task_struct *t; > > > > + > > > > + t = kthread_run(acpi_ec_event_poller, ec, "ec/gpe-%lu", ec->gpe); > > > > > > Does it have to be a kernel thread? > > > > > > What about using a workqueue instead? > > > > Actually I just want to use threaded IRQ here in response to Andi Kleen's comment. > > If acpi_irq is registered as threaded IRQ, then acpi_ec_event_poller() will be the > > callback from it. > > How so? > > > Since ACPICA is not ready for threaded IRQ currently, we cannot proceed at this point. > > So I copied the threaded IRQ code from kernel/irq/manage.c here to prepare threaded IRQ logics. > > Oh dear, no. > > This isn't the way forward here. > > > Using a separate work queue, we didn't decrease the kernel thread count. > > Why does that matter at all? > > > And the code written for the work item cannot be derived when things are > > switched to the threaded IRQ. > > So I used kthread here. > > Please use a workqueue instead. If/when we need to switch over to threaded > IRQs, we'll do the work then. For now, let's not complicate things more > than necessary. It seems we need the thread because we will move polling code from ec_poll() to acpi_ec_event_poller(). This will happen right after these cleanups. That's the threaded IRQ logic - IRQ is polled in the thread. We cannot achieve this using work queue. Best regards -Lv ????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?