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

From: Pekka Enberg
Date: Fri Aug 28 2009 - 09:02:51 EST


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@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?

Page flags and order are probably interesting for tracing?

Pekka

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