Re: QUEUE_FLAG_CLUSTER: not working in 2.6.24 ?

[Mel Gorman <mel@csn.ul.ie>]

On (13/12/07 16:37), Andrew Morton didst pronounce:
> On Thu, 13 Dec 2007 19:30:00 -0500
> Mark Lord <liml@rtr.ca> wrote:
> 
> > Here's the commit that causes the regression:
> > 
> > ...
> >
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -760,7 +760,8 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
> >  		struct page *page = __rmqueue(zone, order, migratetype);
> >  		if (unlikely(page == NULL))
> >  			break;
> > -		list_add_tail(&page->lru, list);
> > +		list_add(&page->lru, list);
> 
> well that looks fishy.
> 

The reasoning behind the change was the first page encountered on the list
by the caller would have a matching migratetype. I failed to take into
account the physical ordering of pages returned. I'm setting up to run some
performance benchmarks of the candidate fix merged into the -mm tree to see
if the search shows up or not. I'm testing against 2.6.25-rc5 but it'll
take a few hours to complete.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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