[pve-devel] default I/O scheduler - CFQ or Deadline?

[Alexandre DERUMIER]

>>Yes, but we measure incredible bad performance with cfq. We get fsync 
>>rates of 250 instead of 3000 on ext4 (factor 12!). So iopriorities makes no 
>>sense if you are already 10 time slower? 

Sure !
3000 fsync with which hardware?  hardware raid with write cache ?

For me it's always use deadline with shared storage and local hardware raid with cache.

Don't need really cfq for reordering the ios, if the cache of the raid card or shared storage can handle this.	



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

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: "Alexandre DERUMIER" <aderumier at odiso.com>, "Martin Maurer" <martin at proxmox.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Mardi 7 Mai 2013 05:48:47 
Objet: RE: [pve-devel] default I/O scheduler - CFQ or Deadline? 

> If I remember, some openvz features works only with cfq ? (ionice, openvz IO 
> priorities) 
> see: 
> http://pve.proxmox.com/pipermail/pve-devel/2012-March/002488.html 

Yes, but we measure incredible bad performance with cfq. We get fsync 
rates of 250 instead of 3000 on ext4 (factor 12!). So iopriorities makes no 
sense if you are already 10 time slower?