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Le jeudi 16 octobre 2008 Ã 08:43 -0500, Anthony Liguori a Ãcrit :
> Laurent Vivier wrote:
> > Hi,
> >
> > I've made a benchmark using a database:
> > mysql and sysbench in OLTP mode.
> >
> > cache=off seems to be the best choice in this case...
> >
>
> It would be interesting for you to run the same workload under KVM.
It is done under KVM... and I've just double checked these values.
> > mysql database
> > http://sysbench.sourceforge.net
> >
> > sysbench --test=oltp
> >
> > 200,000 requests on 2,000,000 rows table.
> >
> > | total time | per-request stat (ms) |
> > | (seconds) | min | avg | max |
> > -----------------+------------+-------+-------+-------+
> > baremetal | 208.6237 | 2.5 | 16.7 | 942.6 |
> > -----------------+------------+-------+-------+-------+
> > cache=on | 642.2962 | 2.5 | 51.4 | 326.9 |
> > -----------------+------------+-------+-------+-------+
> > cache=on,O_DSYNC | 646.6570 | 2.7 | 51.7 | 347.0 |
> > -----------------+------------+-------+-------+-------+
> > cache=off | 635.4424 | 2.9 | 50.8 | 399.5 |
> > -----------------+------------+-------+-------+-------+
> >
>
> Because you're talking about 1/3% of native performance. This means
> that you may be dominated by things like CPU overhead verses actual IO
> throughput.
Yes, but as it is KVM I have no explanation...
I've another interesting result with scsi-generic :
-----------------+------------+-------+-------+-------+
scsi-generic | 634.1303 | 2.8 | 50.7 | 308.6 |
-----------------+------------+-------+-------+-------+
Regards,
Laurent
--
------------------ Laurent.Vivier@xxxxxxxx ------------------
"Tout ce qui est impossible reste à accomplir" Jules Verne
"Things are only impossible until they're not" Jean-Luc Picard
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