Re: [PATCH 2/2] page-allocator: Maintain rolling count of pages tofree from the PCP

[Mel Gorman]

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@xxxxxxxxx> 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?

> 
> > +               } while (--count && --batch_free && !list_empty(list));
> >        }
> >        spin_unlock(&zone->lock);
> >  }
> 

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