Re: Mainline kernel OLTP performance update

Nick Piggin
2009-01-16T07:07:23Z

On Friday 16 January 2009 17:55:47 Matthew Wilcox wrote:
> On Fri, Jan 16, 2009 at 05:46:23PM +1100, Nick Piggin wrote:
> > Intel's OLTP shows SLQB is "neutral" to SLAB. That is, literally within
> > their measurement confidence interval. If it comes down to it, I think we
> > could get them to do more runs to narrow that down, but we're talking a
> > couple of tenths of a percent already.
>
> I think I can speak with some measure of confidence for at least the
> OLTP-testing part of my company when I say that I have no objection to
> Nick's planned merge scheme.
>
> I believe the kernel benchmark group have also done some testing with
> SLQB and have generally positive things to say about it (Yanmin added to
> the gargantuan cc).
>
> Did slabtop get fixed to work with SLQB?

Yes the old slabtop that works on /proc/slabinfo works with SLQB (ie. SLQB
implements /proc/slabinfo).

Lin Ming recently also ported the SLUB /sys/kernel/slab/ specific slabinfo
tool to SLQB. Basically it reports in-depth internal event counts etc. and
can operate on individual caches, making it very useful for performance
"observability" and tuning.

It is hard to come up with a single set of statistics that apply usefully
to all the allocators. FWIW, it would be a useful tool to port over to
SLAB too, if we end up deciding to go with SLAB.