Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932315Ab0GTNBK (ORCPT ); Tue, 20 Jul 2010 09:01:10 -0400 Received: from smtp.nokia.com ([192.100.122.233]:63104 "EHLO mgw-mx06.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757019Ab0GTNBI (ORCPT ); Tue, 20 Jul 2010 09:01:08 -0400 Subject: Re: [RFC][PATCH 14/16] writeback: move bdi threads exiting logic to the forker thread From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Christoph Hellwig Cc: Jens Axboe , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20100718070231.GK23811@infradead.org> References: <1279284312-2411-1-git-send-email-dedekind1@gmail.com> <1279284312-2411-15-git-send-email-dedekind1@gmail.com> <20100718070231.GK23811@infradead.org> Content-Type: text/plain; charset="UTF-8" Date: Tue, 20 Jul 2010 15:54:26 +0300 Message-ID: <1279630466.16462.132.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.30.2 (2.30.2-1.fc13) Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 20 Jul 2010 13:00:53.0721 (UTC) FILETIME=[960A7490:01CB280B] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1650 Lines: 48 On Sun, 2010-07-18 at 03:02 -0400, Christoph Hellwig wrote: > Yes, only killing threads from the caller is much better, that's how > the kthread API is supposed to be used anyway. > > > static void bdi_queue_work(struct backing_dev_info *bdi, > > struct wb_writeback_work *work) > > { > > + bool wakeup_default = false; > > + > > trace_writeback_queue(bdi, work); > > > > spin_lock(&bdi->wb_lock); > > list_add_tail(&work->list, &bdi->work_list); > > - spin_unlock(&bdi->wb_lock); > > - > > /* > > * If the default thread isn't there, make sure we add it. When > > * it gets created and wakes up, we'll run this work. > > */ > > - if (unlikely(!bdi->wb.task)) { > > + if (unlikely(!bdi->wb.task)) > > + wakeup_default = true; > > + else > > + wake_up_process(bdi->wb.task); > > + spin_unlock(&bdi->wb_lock); > > + > > + if (wakeup_default) { > > trace_writeback_nothread(bdi, work); > > wake_up_process(default_backing_dev_info.wb.task); > > Why not simply do the defaul thread wakeup under wb_lock, too? > It keeps the code a lot simpler, and this is not a typical path anyway. Hmm, actually, I want to take this lock in __mark_inode_dirty() as well, so it makes sense to micro-optimize this. Also, can 'trace_writeback_nothread()' be called under a spinlock? If no, then a variable is needed anyway. -- Best Regards, Artem Bityutskiy (Артём Битюцкий) -- 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/