Re: Scaling noise

[Nick Piggin]

Steven Cole wrote:

> On Wed, 2003-09-03 at 20:35, William Lee Irwin III wrote:
>
> > On Wed, Sep 03, 2003 at 08:19:26PM -0600, Steven Cole wrote:
> >
> > > I would never call the SMP locking pathetic, but it could be improved.
> > > Looking at Figure 6 (Star-CD, 1-64 processors on Altix) and Figure 7
> > > (Gaussian 1-32 processors on Altix) on page 13 of "Linux Scalability for
> > > Large NUMA Systems", available for download here:
> > > http://archive.linuxsymposium.org/ols2003/Proceedings/
> > > it appears that for those applications, the curves begin to flatten
> > > rather alarmingly.  This may have little to do with locking overhead.
> > Those numbers are 2.4.x
>
> Yes, I saw that.  It would be interesting to see results for recent
> 2.6.0-textX kernels.  Judging from other recent numbers out of osdl, the
> results for 2.6 should be quite a bit better.  But won't the curves
> still begin to flatten, but at a higher CPU count?  Or has the miracle
> goodness of RCU pushed those limits to insanely high numbers?

They fixed some big 2.4 scalability problems, so it wouldn't be as
impressive as plain 2.4 -> 2.6. However there are obviously hardware
scalability limits as well as software ones. So a more interesting
comparison would of course be 2.6 vs LM's SSI clusters.


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