Re: VFS accounting performance benchmarks

[Francois Tigeot <ftigeot@xxxxxxxxxxxx>]

On Tue, Dec 20, 2011 at 01:50:53PM +0100, Dmitrij D. Czarkoff wrote:
> On Tue, Dec 20, 2011 at 10:07:22AM +0100, Francois Tigeot wrote:
> > 
> > Since VFS accounting uses a per mount-point spinlock to protect its counters, 
> > there is some concern it will degrade write performance on SMP machines.
> > 
> > To measure if this was the case or not, I've run some blogbench benchmarks on
> > a small Xeon system; the details of the test and the results are in the
> > attached PDF.
> 
> I've made a plot which shows the results in more evident way (if I correctly
> understand the test results data).

Heh, nice way to represent the variations, thanks :)

I've done a few more tests with blogbench and I sometimes get more than 12%
variations with the exact same software and hardware.
I'm now convinced blogbench was not a good tool and I'm currently looking
for another benchmark.

-- 
Francois Tigeot