From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 4283C8D003A for ; Tue, 15 Mar 2011 11:21:20 -0400 (EDT) Date: Tue, 15 Mar 2011 11:21:00 -0400 From: Vivek Goyal Subject: Re: [PATCH 2/5] mm: Properly reflect task dirty limits in dirty_exceeded logic Message-ID: <20110315152100.GC24984@redhat.com> References: <1299623475-5512-1-git-send-email-jack@suse.cz> <1299623475-5512-3-git-send-email-jack@suse.cz> <20110309210253.GD10346@redhat.com> <20110314204418.GB4998@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110314204418.GB4998@quack.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Wu Fengguang , Peter Zijlstra , Andrew Morton , Christoph Hellwig , Dave Chinner On Mon, Mar 14, 2011 at 09:44:18PM +0100, Jan Kara wrote: > On Wed 09-03-11 16:02:53, Vivek Goyal wrote: > > On Tue, Mar 08, 2011 at 11:31:12PM +0100, Jan Kara wrote: > > > @@ -291,6 +292,12 @@ static unsigned long task_dirty_limit(struct task_struct *tsk, > > > return max(dirty, bdi_dirty/2); > > > } > > > > > > +/* Minimum limit for any task */ > > > +static unsigned long task_min_dirty_limit(unsigned long bdi_dirty) > > > +{ > > > + return bdi_dirty - bdi_dirty / TASK_LIMIT_FRACTION; > > > +} > > > + > > Should the above be called bdi_min_dirty_limit()? In essense we seem to > > be setting bdi->bdi_exceeded when dirty pages on bdi cross bdi_thresh and > > clear it when dirty pages on bdi are below 7/8*bdi_thresh. So there does > > not seem to be any dependency on task dirty limit here hence string > > "task" sounds confusing to me. In fact, would > > bdi_dirty_exceeded_clear_thresh() be a better name? > See below... > > > > /* > > > * > > > */ > > > @@ -484,9 +491,11 @@ static void balance_dirty_pages(struct address_space *mapping, > > > unsigned long background_thresh; > > > unsigned long dirty_thresh; > > > unsigned long bdi_thresh; > > > + unsigned long min_bdi_thresh = ULONG_MAX; > > > unsigned long pages_written = 0; > > > unsigned long pause = 1; > > > bool dirty_exceeded = false; > > > + bool min_dirty_exceeded = false; > > > struct backing_dev_info *bdi = mapping->backing_dev_info; > > > > > > for (;;) { > > > @@ -513,6 +522,7 @@ static void balance_dirty_pages(struct address_space *mapping, > > > break; > > > > > > bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); > > > + min_bdi_thresh = task_min_dirty_limit(bdi_thresh); > > > bdi_thresh = task_dirty_limit(current, bdi_thresh); > > ^^^^^ > > This patch aside, we use bdi_thresh name both for bdi threshold as well > > as per task per bdi threshold. will task_bdi_thresh be a better name > > here. > I agree that the naming is a bit confusing altough it is traditional :). > The renaming to task_bdi_thresh makes sense to me. Then we could name the > limit when we clear dirty_exceeded as: min_task_bdi_thresh(). The task in > the name tries to say that this is a limit for "any task" so I'd like to > keep it there. What do you think? Ok, so for a task, minimum task_bdi_thresh can be (bdi_dirty - bdi_dirty / TASK_LIMIT_FRACTION). So min_task_dirty_limit() makes sense. Or if you happen to rename above "bdi_thresh" to "task_bdi_thresh" then "min_task_bdi_thresh()" might be even better. It is up to you depending on context of your later patches. Thanks Vivek -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org