Re: poor OSD performance using kernel 3.4

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 30.05.2012 15:27, schrieb Mark Nelson:
> Great, thanks.  I'll try to look at the results later this morning.  If
> you want to look at them yourself you can open them with the blkparse
> program (and seekwatcher too, though there is a bug in the src you have
> to fix to make it work right)
I've no idea about blkparse and seekwatcher - so i don't know what i
should do with the output...

>>> If you could archive/send me the results, that might help us get an idea
>>> of what is actually getting sent out to the disk.  Your data disk
>>> throughput on 3.0 looks pretty close to what I normally get (including
>>> on 3.4).  I'm guessing the issue you are seeing on 3.4 is probably not
>>> the seek problem I mentioned earlier (unless something is causing so
>>> many seeks that it more or less paralyzes the disk).
>> As i have a SSD i can't believe seeks can be a problem.
> 
> Ah, sorry. I  forgot you were on SSD.  Honestly I'm surpised that with
> 3.0 you weren't getting better performance.  Something to look into once
> we figure out why your 3.4 performance is so bad!
Yes i think this is another problem.

Stefan