Re: iwlagn: order 2 page allocation failures

Mel Gorman
2009-09-11T08:47:14Z

On Thu, Sep 10, 2009 at 02:14:50PM -0700, reinette chatre wrote:
> On Thu, 2009-09-10 at 02:02 -0700, Mel Gorman wrote:
>
> >
> > As a total aside, there is still the problem that the driver is depending on
> > order-2 allocations. On systems without swap, the allocation problem could be
> > more severe as there are fewer pages the system can use to regain contiguity.
>
> I looked more at the implementation and hardware interface but I do not
> see a way around this. We have to provide 8k buffer to device, and we
> have to make sure it is aligned.
>

That would imply an order-1 allocation instead of an order-2 though so
it would appear than we are being worse than we have to. It would appear
to be because of this +256 bytes that goes onto every buffer.

> Do you have any suggestions?
>

Nothing concrete. Finding an alternative to having the socket buffer
8192+256 to make it an order-1 allocation would be an improvement but I
don't know how that should be tackled. Lacking the hardware, I can't
experiment myself :(

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