Re: No, really, stop trying to delete slab until you've finished making slub perform as well

From: Jamie Lokier
Date: Mon Aug 04 2008 - 10:48:45 EST


Christoph Lameter wrote:
> Matthew Wilcox wrote:
> > On Fri, May 09, 2008 at 07:21:01PM -0700, Christoph Lameter wrote:
> >> - Add a patch that obsoletes SLAB and explains why SLOB does not support
> >> defrag (Either of those could be theoretically equipped to support
> >> slab defrag in some way but it seems that Andrew/Linus want to reduce
> >> the number of slab allocators).
> >
> > Do we have to once again explain that slab still outperforms slub on at
> > least one important benchmark? I hope Nick Piggin finds time to finish
> > tuning slqb; it already outperforms slub.
> >
>
> Uhh. I forgot to delete that statement. I did not include the patch
> in the series.
>
> We have a fundamental issue design issue there. Queuing on free can result in
> better performance as in SLAB. However, it limits concurrency (per node lock
> taking) and causes latency spikes due to queue processing (f.e. one test load
> had 118.65 vs. 34 usecs just by switching to SLUB).

Vaguely on this topic, has anyone studied the effects of SLAB/SLUB
etc. on MMUless systems?

-- Jamie
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