On Tue, 2007-09-04 at 23:58 -0700, Christoph Lameter wrote: > On Wed, 5 Sep 2007, Zhang, Yanmin wrote: > > > On Tue, 2007-09-04 at 20:59 -0700, Christoph Lameter wrote: > > > On Wed, 5 Sep 2007, Zhang, Yanmin wrote: > > > > > > > 8) kmalloc-4096 order is 1 which means one slab consists of 2 objects. > > > > So a > > > > > > You can change that by booting with slub_max_order=0. Then we can also > > > use > > > the per cpu queues to get these order 0 objects which may speed up the > > > allocations because we do not have to take zone locks on slab allocation. > > > > > > Note also that Andrew's tree has a page allocator pass through for SLUB > > > for 4k kmallocs bypassing slab completely. That may also address the > > > issue. > > > > > > If you want SLUB to handle more objects in the 4k kmalloc cache > > > without going to the page allocator then you can boot f.e. with > > > > > > slub_max_order=3 slub_min_objects=8 > > I tried this approach. The testing result showed 2.6.23-rc4 is about > > 2.5% better than 2.6.22. It really resovles the issue. > > > > However, the approach treats the slabs in the same policy. Could we > > implement a per-slab specific approach like direct b)? > > I am not sure what you mean by same policy. Same configuration for all > slabs? Yes.
> > > > Try the ways to address the issue that I mentioned above. > > I really appreciate your kind comments! > > Would it be possible to try the two other approaches that I suggested? I > think both of those may also solve the issue. Try booting with > slab_max_order=0 1) I tried slab_max_order=0 and the regression becomes 12.5%. It's still not good. 2) I apllied patch slub-direct-pass-through-of-page-size-or-higher-kmalloc.patch to kernel 2.6.23-rc4. The new testing result is much better, only 1% less than 2.6.22. So the best solution is booting kernel with "slub_max_order=3 slub_min_objects=8". > and see what effect it has. The queues of the page > allocator can be much larger than what slab has for 4k pages. There is > really not much of a point in using a slab allocator for page sized > allocations. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
