From: Mel Gorman <mgorman@suse.de>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>,
akpm@linux-foundation.org, Ury Stankevich <urykhy@gmail.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
stable@kernel.org
Subject: Re: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous
Date: Mon, 6 Jun 2011 15:55:17 +0100 [thread overview]
Message-ID: <20110606145517.GG5247@suse.de> (raw)
In-Reply-To: <20110606123851.GA12887@random.random>
On Mon, Jun 06, 2011 at 02:38:51PM +0200, Andrea Arcangeli wrote:
> On Mon, Jun 06, 2011 at 11:39:24AM +0100, Mel Gorman wrote:
> > Well spotted.
> >
> > Acked-by: Mel Gorman <mgorman@suse.de>
> >
> > Minor nit. swapper_space is rarely referred to outside of the swap
> > code. Might it be more readable to use
> >
> > /*
> > * swapcache is accounted as NR_FILE_PAGES but it is not
> > * accounted as NR_SHMEM
> > *
> > if (PageSwapBacked(page) && !PageSwapCache(page))
>
> I thought the comparison on swapper_space would be faster as it was
> immediate vs register in CPU, instead of forcing a memory
> access. Otherwise I would have used the above. Now the test_bit is
> written in C and lockless so it's not likely to be very different
> considering the cacheline is hot in the CPU but it's still referencing
> memory instead register vs immediate comparison.
Ok, I had not considered that. That is a micro-optimisation but it's
there. I thought my version is more readable and migration is not
really a fast path but yours is still better.
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2011-06-06 14:55 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-30 13:13 [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous Mel Gorman
2011-05-30 14:31 ` Andrea Arcangeli
2011-05-30 15:37 ` Mel Gorman
2011-05-30 16:55 ` Mel Gorman
2011-05-30 17:53 ` Andrea Arcangeli
2011-05-31 12:16 ` Minchan Kim
2011-05-31 12:24 ` Andrea Arcangeli
2011-05-31 13:33 ` Minchan Kim
2011-05-31 14:14 ` Andrea Arcangeli
2011-05-31 14:37 ` Minchan Kim
2011-05-31 14:38 ` Minchan Kim
2011-06-02 18:23 ` Andrea Arcangeli
2011-06-02 20:21 ` Minchan Kim
2011-06-02 20:59 ` Minchan Kim
2011-06-02 22:03 ` Andrea Arcangeli
2011-06-02 21:40 ` Andrea Arcangeli
2011-06-02 22:23 ` Minchan Kim
2011-06-02 22:32 ` Andrea Arcangeli
2011-06-02 23:01 ` Minchan Kim
2011-06-03 17:37 ` Andrea Arcangeli
2011-06-03 18:07 ` Andrea Arcangeli
2011-06-04 7:59 ` Minchan Kim
2011-06-06 10:32 ` Mel Gorman
2011-06-06 12:49 ` Andrea Arcangeli
2011-06-06 14:47 ` Mel Gorman
2011-06-06 14:07 ` Minchan Kim
2011-06-06 10:15 ` Mel Gorman
2011-06-06 10:26 ` Mel Gorman
2011-06-06 14:01 ` Minchan Kim
2011-06-06 14:26 ` Minchan Kim
2011-06-02 23:02 ` Minchan Kim
2011-06-01 0:57 ` Mel Gorman
2011-06-01 9:24 ` Mel Gorman
2011-06-01 17:58 ` Mel Gorman
2011-06-01 19:15 ` Andrea Arcangeli
2011-06-01 21:40 ` Mel Gorman
2011-06-01 23:30 ` Andrea Arcangeli
2011-06-02 1:03 ` Mel Gorman
2011-06-02 8:34 ` Minchan Kim
2011-06-02 13:29 ` Andrea Arcangeli
2011-06-02 14:50 ` Mel Gorman
2011-06-02 15:37 ` Andrea Arcangeli
2011-06-03 2:09 ` Mel Gorman
2011-06-03 14:49 ` Mel Gorman
2011-06-03 15:45 ` Andrea Arcangeli
2011-06-04 7:25 ` Minchan Kim
2011-06-06 10:39 ` Mel Gorman
2011-06-06 12:38 ` Andrea Arcangeli
2011-06-06 14:55 ` Mel Gorman [this message]
2011-06-06 14:19 ` Minchan Kim
2011-06-06 22:32 ` Andrew Morton
2011-06-04 6:58 ` Minchan Kim
2011-06-06 10:43 ` Mel Gorman
2011-06-06 12:40 ` Andrea Arcangeli
2011-06-06 13:27 ` Minchan Kim
2011-06-06 13:23 ` Minchan Kim
2011-05-31 14:34 ` Mel Gorman
2011-05-30 14:45 ` [stable] " Greg KH
2011-05-30 16:14 ` Minchan Kim
2011-05-31 8:32 ` Mel Gorman
2011-05-31 4:48 ` KAMEZAWA Hiroyuki
2011-05-31 5:38 ` Minchan Kim
2011-05-31 7:14 ` KOSAKI Motohiro
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