[pve-devel] less cores more iops / speed

[Alexandre DERUMIER]

>> Right now RBD in KVM is limited by CPU speed. 

Good to known, so it's seem lack of threading, or maybe somes locks. (so faster cpu give more iops).

If you lauch parallel fio on same host on different guest, do you get more total iops ? (for me it's scale)

if you launch 2 parallel fio, on same guest (on differents disk), do you get more iops ? (for me, it doesn't scale, so raid0 in guest doesn't help).




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

De: "Stefan Priebe" <s.priebe at profihost.ag> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: "eric" <eric at netwalk.com>, pve-devel at pve.proxmox.com 
Envoyé: Dimanche 11 Novembre 2012 13:07:36 
Objet: Re: [pve-devel] less cores more iops / speed 

Am 11.11.2012 12:12, schrieb Alexandre DERUMIER: 
> If I remember good, stefan can achieve 100.000 iops with iscsi with same kvm host. 

Correct but this was always with scsi-generic and I/O multipathing on 
host. rbd does not support scsi-generic ;-( 

> I have checked ceph mailing, stefan seem to have resolved his problem with dual core with bios update ! 
Correct. So speed on Dual Xeon is now 14.000 IOP/s and 18.000 IOP/s on 
Single Xeon. But the difference is an issue of the CPU Speed. 3,6Ghz 
Single Xeon vs. 2.5Ghz Dual Xeon. 

Right now RBD in KVM is limited by CPU speed. 

Greets, 
Stefan