Re: [PATCH] Re: kswapd stuck using 100% CPU

From: Mel Gorman
Date: Mon Mar 26 2012 - 09:56:29 EST

On Mon, Mar 26, 2012 at 01:40:41PM +0300, Pekka Enberg wrote:
> On Mon, Mar 26, 2012 at 12:32 PM, Mel Gorman <mel@xxxxxxxxx> wrote:
> > On Sat, Mar 24, 2012 at 10:26:21AM -0400, Rik van Riel wrote:
> >>
> >> Only test compaction_suitable if the kernel is built with CONFIG_COMPACTION,
> >> otherwise the stub compaction_suitable function will always return
> >> COMPACT_SKIPPED and send kswapd into an infinite loop.
> >>
> >> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
> >> Reported-by: Anton Blanchard <anton@xxxxxxxxx>
> >
> > Acked-by: Mel Gorman <mel@xxxxxxxxx>
> The API looks fragile and this patch isn't exactly making it any
> better. Why don't we make compaction_suitable() return something other

Returning COMPACT_PARTIAL or COMPACT_CONTINUE would confuse the check in
should_continue_reclaim. A fourth return type could be added but an
obvious name does not spring to mind that would end up being similar to
just adding a CONFIG_COMPACTION check.

Mel Gorman
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