Re: [this_cpu_xx V6 7/7] this_cpu: slub aggressive use of this_cpuoperations in the hotpaths
From: Christoph Lameter
Date: Wed Oct 14 2009 - 12:05:13 EST
On Wed, 14 Oct 2009, Pekka Enberg wrote:
> SLAB is able to queue lots of large objects but SLUB can't do that because it
> has no queues. In SLUB, each CPU gets a page assigned to it that serves as a
> "queue" but the size of the queue gets smaller as object size approaches page
> size.
>
> We try to offset that with higher order allocations but IIRC we don't increase
> the order linearly with object size and cap it to some reasonable maximum.
You can test to see if larger pages have an influence by passing
slub_max_order=6
or so on the kernel command line.
You can force a large page use in slub by setting
slub_min_order=3
f.e.
Or you can force a mininum number of objecxcts in slub through f.e.
slub_min_objects=50
slub_max_order=6 slub_min_objects=50
should result in pretty large slabs with lots of in page objects that
allow slub to queue better.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/