Re: Newer kernels and CFS scheduler again

>________________________________
> From: Glyn Astill <glynastill@yahoo.co.uk>
>To: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>
>Sent: Tuesday, 30 April 2013, 16:58
>Subject: [GENERAL] Newer kernels and CFS scheduler again
>
>Hi All,
>
>
>As I'll soon be looking at migrating some of our debian servers onto the new stable release, I've started doing a bit
ofbasic pgbench testing. 
>
>
>Initially I've seen a little performance regression with higher concurrent clients when going from the 2.6.32 kernel
to3.2.14 (select only and tpc-b).  After trying the suggestions made by Shaun Thomas a while back (here:
http://www.postgresql.org/message-id/50E4AAB1.9040902@optionshouse.com)and getting nowhere, I'm seeing big improvements
insteadincreasing the  
>

Slight correction, I meant 3.2.41

>defaults for sched_min_granularity_ns and sched_wakeup_granularity_ns (As described here:
https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt)from debians defaults of 3000000 and 4000000
respectively.
>
>
>
>On my initial test setup (which admittedly is far from cutting edge) of 2xE5320 / 32Gb the following seem pretty
optimal:
>
>
>kernel.sched_min_granularity_ns=9000000
>kernel.sched_wakeup_granularity_ns=12000000
>
>
>I've yet to do any testing on our larger machines, but as there have been a few posts here about performance vs newer
kernelsI was just wondering what other peoples findings are regarding CFS? 
>
>
>Glyn
>
>