Re: QUEUE_FLAG_CLUSTER: not working in 2.6.24 ?

[James Bottomley]

On Thu, 2007-12-13 at 14:02 -0800, Andrew Morton wrote:
> On Thu, 13 Dec 2007 21:09:59 +0100
> Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
> 
> >
> > OK, it's a vm issue,
> 
> cc linux-mm and probable culprit.
> 
> >  I have tens of thousand "backward" pages after a
> > boot - IOW, bvec->bv_page is the page before bvprv->bv_page, not
> > reverse. So it looks like that bug got reintroduced.
> 
> Bill Irwin fixed this a couple of years back: changed the page allocator so
> that it mostly hands out pages in ascending physical-address order.
> 
> I guess we broke that, quite possibly in Mel's page allocator rework.
> 
> It would help if you could provide us with a simple recipe for
> demonstrating this problem, please.

The simple way seems to be to malloc a large area, touch every page and
then look at the physical pages assigned ... they now mostly seem to be
descending in physical address.

James


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