Re: poor OSD performance using kernel 3.4

[Alexandre DERUMIER <aderumier@odiso.com>]

fio benchmark will give you raw device performance bypassing filesystem.

So maybe the problem is in xfs or linux vfs layer.

I think you need to bench the filesystem to compare performance


----- Mail original ----- 

De: "Stefan Priebe - Profihost AG" <s.priebe@profihost.ag> 
À: "Alexandre DERUMIER" <aderumier@odiso.com> 
Cc: ceph-devel@vger.kernel.org, "Mark Nelson" <mark.nelson@inktank.com> 
Envoyé: Mardi 29 Mai 2012 10:22:34 
Objet: Re: poor OSD performance using kernel 3.4 

Am 29.05.2012 05:54, schrieb Alexandre DERUMIER: 
>>> This happens with ext4 or btrfs too. 
> 
> maybe this is related to io scheduler ? 
> did you have compared cfq,deadline,noop scheduler ? 

This is something i consider for performance tuning later on, when 
everything is running smooth. Right now i'm using CFQ with the tuned IBM 
settings (which proxmox uses too). 


Here are some outputs of basic fio Tests running on 3.4 and 3.0. 

3.4: http://pastebin.com/raw.php?i=6GEKsCYH 
3.0: http://pastebin.com/raw.php?i=FU4AtUck 

strangely 3.4 is faster but this corresponds to the fact that the normal 
Disk I/O is working fine with 3.4 It's just ceph which isn't working fine. 

> also what's is your sas/sata controller ? 
Intel onboard SATA controller in this testsetup. 

Stefan 



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	Alexandre D erumier 
Ingénieur Système 
Fixe : 03 20 68 88 90 
Fax : 03 20 68 90 81 
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