On Thu, 27 Nov 2008, Eric Dumazet wrote:

The last point is about SLUB being hit hard, unless we
use slub_min_order=3 at boot, or we use Christoph Lameter
patch (struct file RCU optimizations)
http://thread.gmane.org/gmane.linux.kernel/418615

If we boot machine with slub_min_order=3, SLUB overhead disappears.

I'd rather not be that drastic. Did you try increasing slub_min_objects
instead? Try 40-100. If we find the right number then we should update
the tuning to make sure that it pickes the right slab page sizes.