On Wed, May 29, 2019 at 11:37 AM Robert Sander <r.san...@heinlein-support.de>
wrote:

> Hi,
>
> Am 29.05.19 um 11:19 schrieb Martin Verges:
> >
> >     We have identified the performance settings in the BIOS as a major
> >     factor
> >
> > could you share your insights what options you changed to increase
> > performance and could you provide numbers to it?
>
> Most default perfomance settings nowadays seem to be geared towards
> power savings. This decreases CPU frequencies and does not play well
> with Ceph (and virtualization).
>

Agreed, disabling C states can help, disabling dynamic underclocking can
also help.

No need to that in the BIOS, setting that via linux-cpupower and similar
tools is enough.

Another thing that can help is this:

net.ipv4.tcp_low_latency=1

But all of these are to get last drop of IOPS out if you are already
gettings lots of IOPS,
it's not something that helps if your disk is only getting 1000 IOPS.

Paul


>
> There was just one setting in the BIOS of these machines called "Host
> Performance" that was set to "Balanced". We changed that to "Max
> Performance" and immediately the throughput doubled.
>
> Regards
> --
> Robert Sander
> Heinlein Support GmbH
> Linux: Akademie - Support - Hosting
> http://www.heinlein-support.de
>
> Tel: 030-405051-43
> Fax: 030-405051-19
>
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