Re: [Bug 8464] New: autoreconf: page allocation failure. order:2, mode:0x84020

[Christoph Lameter <clameter@sgi.com>]

On Thu, 10 May 2007, Mel Gorman wrote:

> > I cannot predict how allocations on a slab will be performed. In order 
> > to avoid the higher order allocations in we would have to add a flag 
> > that tells SLUB at slab creation creation time that this cache will be 
> > used for atomic allocs and thus we can avoid configuring slabs in such a 
> > way that they use higher order allocs.
> > 
> 
> It is an option. I had the gfp flags passed in to kmem_cache_create() in
> mind for determining this but SLUB creates slabs differently and different
> flags could be passed into kmem_cache_alloc() of course.

So we have a collection of flags to add

SLAB_USES_ATOMIC
SLAB_TEMPORARY
SLAB_PERSISTENT
SLAB_RECLAIMABLE
SLAB_MOVABLE

?

> Another alternative is that anti-frag used to also group high-order
> allocations together and make it hard to fallback to those areas
> for non-atomic allocations. It is currently backed out by the
> patch dont-group-high-order-atomic-allocations.patch because
> it was intended for rare high-order short-lived allocations
> such as e1000 that are currently dealt with by MIGRATE_RESERVE
> (bias-the-location-of-pages-freed-for-min_free_kbytes-in-the-same-max_order_nr_pages-blocks.patch)
>  The high-order atomic groupings may help here because the high-order
> allocations are long-lived and would claim contiguous areas.
> 
> The last alternative I think I mentioned already is to have the minimum
> order kswapd reclaims as the same order SLUB uses instead of 0 so that
> min_free_kbytes is kept at higher orders than current.

Would you get a patch to Nicholas to test either of these solutions?

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