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Subject: Re: [PATCH 2/2] page-allocator: Maintain rolling count of pages to
 free from the PCP
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Linux Memory Management List <linux-mm@kvack.org>,
       Christoph Lameter <cl@linux-foundation.org>,
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Date: Fri, 28 Aug 2009 16:02:44 +0300
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Hi Mel,

On Fri, 2009-08-28 at 13:57 +0100, Mel Gorman wrote:
> On Fri, Aug 28, 2009 at 03:16:34PM +0300, Pekka Enberg wrote:
> > Hi Mel,
> > 
> > On Fri, Aug 28, 2009 at 11:44 AM, Mel Gorman<mel@csn.ul.ie> wrote:
> > > -               page = list_entry(list->prev, struct page, lru);
> > > -               /* have to delete it as __free_one_page list manipulates */
> > > -               list_del(&page->lru);
> > > -               trace_mm_page_pcpu_drain(page, 0, migratetype);
> > > -               __free_one_page(page, zone, 0, migratetype);
> > > +               do {
> > > +                       page = list_entry(list->prev, struct page, lru);
> > > +                       /* must delete as __free_one_page list manipulates */
> > > +                       list_del(&page->lru);
> > > +                       __free_one_page(page, zone, 0, migratetype);
> > > +                       trace_mm_page_pcpu_drain(page, 0, migratetype);
> > 
> > This calls trace_mm_page_pcpu_drain() *after* __free_one_page(). It's
> > probably not a good idea as __free_one_page() can alter the struct
> > page in various ways.
> > 
> 
> While true, does it alter the struct page in any way that matters?

Page flags and order are probably interesting for tracing?

			Pekka