From: Mel Gorman <mel@csn.ul.ie>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Chris Mason <chris.mason@oracle.com>,
Dave Chinner <david@fromorbit.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH 02/10] vmscan: move priority variable into scan_control
Date: Wed, 26 May 2010 11:23:30 +0100 [thread overview]
Message-ID: <20100526102330.GL29038@csn.ul.ie> (raw)
In-Reply-To: <20100416224820.GE20640@cmpxchg.org>
Sorry for the long delay on this. I got distracted by the anon_vma and
page migration stuff.
On Sat, Apr 17, 2010 at 12:48:20AM +0200, Johannes Weiner wrote:
> On Thu, Apr 15, 2010 at 06:21:35PM +0100, Mel Gorman wrote:
> > From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> >
> > Now very lots function in vmscan have `priority' argument. It consume
> > stack slightly. To move it on struct scan_control reduce stack.
>
> I don't like this much because it obfuscates value communication.
>
> Functions no longer have obvious arguments and return values, as it's all
> passed hidden in that struct.
>
> Do you think it's worth it? I would much rather see that thing die than
> expand on it...
I don't feel strongly enough to fight about it and reducing stack usage here
isn't the "fix" anyway. I'll drop this patch for now.
That aside, the page reclaim algorithm maintains a lot of state and the
"priority" is part of that state. While the struct means that functions might
not have obvious arguments, passing the state around as arguments gets very
unwieldly very quickly. I don't think killing scan_control would be as
nice as you imagine although I do think it should be as small as
possible.
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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next prev parent reply other threads:[~2010-05-26 10:23 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-15 17:21 [RFC PATCH 00/10] Reduce stack usage used by page reclaim V1 Mel Gorman
2010-04-15 17:21 ` [PATCH 01/10] vmscan: kill prev_priority completely Mel Gorman
2010-04-16 22:37 ` Johannes Weiner
2010-04-15 17:21 ` [PATCH 02/10] vmscan: move priority variable into scan_control Mel Gorman
2010-04-16 22:48 ` Johannes Weiner
2010-05-26 10:23 ` Mel Gorman [this message]
2010-05-28 2:39 ` KOSAKI Motohiro
2010-04-15 17:21 ` [PATCH 03/10] vmscan: simplify shrink_inactive_list() Mel Gorman
2010-04-16 22:54 ` Johannes Weiner
2010-04-15 17:21 ` [PATCH 04/10] vmscan: Remove useless loop at end of do_try_to_free_pages Mel Gorman
2010-04-16 2:48 ` KOSAKI Motohiro
2010-04-16 22:56 ` Johannes Weiner
2010-04-15 17:21 ` [PATCH 05/10] vmscan: Remove unnecessary temporary vars in do_try_to_free_pages Mel Gorman
2010-04-16 2:47 ` KOSAKI Motohiro
2010-04-15 17:21 ` [PATCH 06/10] vmscan: Split shrink_zone to reduce stack usage Mel Gorman
2010-04-16 4:23 ` Dave Chinner
2010-04-16 14:27 ` Mel Gorman
2010-04-16 6:26 ` KOSAKI Motohiro
2010-04-16 23:14 ` Johannes Weiner
2010-04-15 17:21 ` [PATCH 07/10] vmscan: Remove unnecessary temporary variables in shrink_zone() Mel Gorman
2010-04-16 2:51 ` KOSAKI Motohiro
2010-04-16 23:03 ` Johannes Weiner
2010-05-26 11:21 ` Mel Gorman
2010-05-28 2:51 ` KOSAKI Motohiro
2010-04-15 17:21 ` [PATCH 08/10] vmscan: Setup pagevec as late as possible in shrink_inactive_list() Mel Gorman
2010-04-16 4:27 ` Dave Chinner
2010-04-16 6:30 ` KOSAKI Motohiro
2010-04-16 14:31 ` Mel Gorman
2010-04-16 23:28 ` Johannes Weiner
2010-04-15 17:21 ` [PATCH 09/10] vmscan: Setup pagevec as late as possible in shrink_page_list() Mel Gorman
2010-04-16 7:54 ` KOSAKI Motohiro
2010-04-16 14:34 ` Mel Gorman
2010-04-15 17:21 ` [PATCH 10/10] vmscan: Update isolated page counters outside of main path in shrink_inactive_list() Mel Gorman
2010-04-16 11:19 ` KOSAKI Motohiro
2010-04-16 14:35 ` Mel Gorman
2010-04-16 23:34 ` Johannes Weiner
2010-04-16 14:50 ` [RFC PATCH 00/10] Reduce stack usage used by page reclaim V1 Mel Gorman
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