From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Mel Gorman <mel@csn.ul.ie>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, Dave Chinner <david@fromorbit.com>,
Chris Mason <chris.mason@oracle.com>,
Nick Piggin <npiggin@suse.de>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 6/6] vmscan: Do not writeback pages in direct reclaim
Date: Fri, 11 Jun 2010 10:43:31 -0700 [thread overview]
Message-ID: <20100611104331.d8463580.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100611162523.GA24707@infradead.org>
On Fri, 11 Jun 2010 12:25:23 -0400 Christoph Hellwig <hch@infradead.org> wrote:
> On Thu, Jun 10, 2010 at 11:17:06PM -0700, Andrew Morton wrote:
> > As it stands, it would be wildly incautious to make a change like
> > this without first working out why we're pulling so many dirty pages
> > off the LRU tail, and fixing that.
>
> Note that unlike the writepage vs writepages from kswapd which can
> be fixed by the right tuning this is a black or white issue. Writeback
> from direct reclaim will kill your stack if the caller happens to be
> the wrong one, and just making it happen less often is not a fix - it
> must not happen at all.
Of course, but making a change like that in the current VM will cause a
large number of dirty pages to get refiled, so the impact of this
change on some workloads could be quite bad.
If, however, we can get things back to the state where few dirty pages
ever reach the tail of the LRU then the adverse impact of this change
will be much less.
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next prev parent reply other threads:[~2010-06-11 17:43 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-08 9:02 [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim and use a_ops->writepages() where possible Mel Gorman
2010-06-08 9:02 ` [PATCH 1/6] tracing, vmscan: Add trace events for kswapd wakeup, sleeping and direct reclaim Mel Gorman
2010-06-08 9:02 ` [PATCH 2/6] tracing, vmscan: Add trace events for LRU page isolation Mel Gorman
2010-06-08 9:02 ` [PATCH 3/6] tracing, vmscan: Add trace event when a page is written Mel Gorman
2010-06-08 9:02 ` [PATCH 4/6] tracing, vmscan: Add a postprocessing script for reclaim-related ftrace events Mel Gorman
2010-06-08 9:02 ` [PATCH 5/6] vmscan: Write out ranges of pages contiguous to the inode where possible Mel Gorman
2010-06-11 6:10 ` Andrew Morton
2010-06-11 12:49 ` Mel Gorman
2010-06-11 19:07 ` Andrew Morton
2010-06-11 20:44 ` Mel Gorman
2010-06-11 21:33 ` Andrew Morton
2010-06-12 0:17 ` Mel Gorman
2010-06-11 16:27 ` Christoph Hellwig
2010-06-08 9:02 ` [PATCH 6/6] vmscan: Do not writeback pages in direct reclaim Mel Gorman
2010-06-11 6:17 ` Andrew Morton
2010-06-11 12:54 ` Mel Gorman
2010-06-11 16:25 ` Christoph Hellwig
2010-06-11 17:43 ` Andrew Morton [this message]
2010-06-11 17:49 ` Christoph Hellwig
2010-06-11 18:13 ` Mel Gorman
2010-06-08 9:08 ` [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim and use a_ops->writepages() where possible Christoph Hellwig
2010-06-08 9:28 ` Mel Gorman
2010-06-11 16:29 ` Christoph Hellwig
2010-06-11 18:15 ` Mel Gorman
2010-06-11 19:12 ` Chris Mason
2010-06-09 2:52 ` KAMEZAWA Hiroyuki
2010-06-09 9:52 ` Mel Gorman
2010-06-10 0:38 ` KAMEZAWA Hiroyuki
2010-06-10 1:10 ` Mel Gorman
2010-06-10 1:29 ` KAMEZAWA Hiroyuki
2010-06-11 5:57 ` Andrew Morton
2010-06-11 12:33 ` Mel Gorman
2010-06-11 16:30 ` Christoph Hellwig
2010-06-11 18:17 ` Mel Gorman
2010-06-15 14:00 ` Andrea Arcangeli
2010-06-15 14:11 ` Christoph Hellwig
2010-06-15 14:22 ` Andrea Arcangeli
2010-06-15 14:43 ` Christoph Hellwig
2010-06-15 15:08 ` Andrea Arcangeli
2010-06-15 15:25 ` Christoph Hellwig
2010-06-15 15:45 ` Andrea Arcangeli
2010-06-15 16:26 ` Christoph Hellwig
2010-06-15 16:31 ` Andrea Arcangeli
2010-06-15 16:49 ` Rik van Riel
2010-06-15 16:54 ` Christoph Hellwig
2010-06-15 19:13 ` Rik van Riel
2010-06-15 19:17 ` Christoph Hellwig
2010-06-15 19:44 ` Chris Mason
2010-06-16 7:57 ` Nick Piggin
2010-06-16 16:59 ` Rik van Riel
2010-06-16 17:04 ` Andrea Arcangeli
2010-06-15 16:54 ` Nick Piggin
2010-06-15 15:38 ` Mel Gorman
2010-06-15 16:14 ` Andrea Arcangeli
2010-06-15 16:22 ` Christoph Hellwig
2010-06-15 16:30 ` Mel Gorman
2010-06-15 16:34 ` Mel Gorman
2010-06-15 16:54 ` Andrea Arcangeli
2010-06-15 16:35 ` Christoph Hellwig
2010-06-15 16:37 ` Andrea Arcangeli
2010-06-15 17:43 ` Christoph Hellwig
2010-06-15 16:45 ` Christoph Hellwig
2010-06-15 14:51 ` Mel Gorman
2010-06-15 14:55 ` Rik van Riel
2010-06-15 15:08 ` Nick Piggin
2010-06-15 15:10 ` Mel Gorman
2010-06-15 16:28 ` Andrea Arcangeli
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