Re: [patch] SLQB slab allocator

Christoph Lameter
2009-01-23T15:35:22Z

On Thu, 22 Jan 2009, Pekka Enberg wrote:

> On Wed, 2009-01-21 at 19:13 -0500, Christoph Lameter wrote:
> > No it cannot because in SLUB objects must come from the same page.
> > Multiple objects in a queue will only ever require a single page and not
> > multiple like in SLAB.
>
> There's one potential problem with "per-page queues", though. The bigger
> the object, the smaller the "queue" (i.e. less objects per page). Also,
> partial lists are less likely to help for big objects because they get
> emptied so quickly and returned to the page allocator. Perhaps we should
> do a small "full list" for caches with large objects?

Right thats why there is need for higher order allocs because that
increases the "queue" sizes. If the pages are larger then also the partial
lists will cover more ground. Much of the tuning in SLUB is the page size
setting (remember you can set the order for each slab in slub!). In
SLAB/SLQB the corresponding tuning is through the queue sizes.