From: Mel Gorman <mgorman@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>, Xishi Qiu <qiuxishi@huawei.com>,
riel@redhat.com, aquini@redhat.com, linux-mm@kvack.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: skip the page buddy block instead of one page
Date: Wed, 14 Aug 2013 23:22:41 +0100 [thread overview]
Message-ID: <20130814222241.GQ2296@suse.de> (raw)
In-Reply-To: <20130814132602.814a88e991e29c5b93bbe22c@linux-foundation.org>
On Wed, Aug 14, 2013 at 01:26:02PM -0700, Andrew Morton wrote:
> On Thu, 15 Aug 2013 00:52:29 +0900 Minchan Kim <minchan@kernel.org> wrote:
>
> > On Wed, Aug 14, 2013 at 09:57:11AM +0100, Mel Gorman wrote:
> > > On Wed, Aug 14, 2013 at 12:45:41PM +0800, Xishi Qiu wrote:
> > > > A large free page buddy block will continue many times, so if the page
> > > > is free, skip the whole page buddy block instead of one page.
> > > >
> > > > Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
> > >
> > > page_order cannot be used unless zone->lock is held which is not held in
> > > this path. Acquiring the lock would prevent parallel allocations from the
> >
> > Argh, I missed that.
>
> I missed it as well. And so did Xishi Qiu.
>
> Mel, we have a problem. What can we do to make this code more
> maintainable?
I sit in the bad man corner until I write a comment patch :/
page_order already has a comment but obviously the call site on compaction.c
could do with a hint. As I think the consequences of this race can be
dealt with I'm hoping Xishi Qiu will take the example I posted, fix it
if it needs fixing, turn it into a real patch and run it through whatever
test case led him to find this problem in the first place (HINT HINT). If
that happens, great! If not, I might do it myself and failing that, I'll
post a patch adding a comment explaining why page_order is not used there.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2013-08-14 22:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-14 4:45 [PATCH] mm: skip the page buddy block instead of one page Xishi Qiu
2013-08-14 7:07 ` Minchan Kim
2013-08-14 8:57 ` Mel Gorman
2013-08-14 9:14 ` Xishi Qiu
2013-08-14 15:52 ` Minchan Kim
2013-08-14 16:16 ` Mel Gorman
2013-08-14 16:39 ` Minchan Kim
2013-08-14 18:00 ` Mel Gorman
2013-08-14 19:11 ` Minchan Kim
2013-08-15 2:32 ` Xishi Qiu
2013-08-15 2:44 ` Minchan Kim
2013-08-15 3:46 ` Xishi Qiu
2013-08-15 4:17 ` Minchan Kim
2013-08-15 4:24 ` Minchan Kim
2013-08-15 7:45 ` Xishi Qiu
[not found] ` <20130815095102.GA4449@hacker.(null)>
2013-08-15 11:15 ` Xishi Qiu
2013-08-15 11:17 ` Xishi Qiu
2013-08-15 6:38 ` Xishi Qiu
2013-08-15 11:30 ` Mel Gorman
2013-08-15 13:19 ` Minchan Kim
2013-08-15 13:42 ` Mel Gorman
2013-08-15 14:16 ` Minchan Kim
2013-08-14 20:26 ` Andrew Morton
2013-08-14 22:22 ` Mel Gorman [this message]
2014-01-17 14:32 ` [PATCH] mm: Improve documentation of page_order Mel Gorman
2014-01-17 18:40 ` Rafael Aquini
2014-01-17 18:53 ` Laura Abbott
2014-01-17 19:59 ` Mel Gorman
2014-01-21 11:05 ` [PATCH] mm: Improve documentation of page_order v2 Mel Gorman
2014-01-20 6:12 ` [PATCH] mm: Improve documentation of page_order Minchan Kim
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