[pve-devel] less cores more iops / speed

[Alexandre DERUMIER]

>>One VM on one Host: 18.000 IOP/s 
>>Two VM on one Host: 2x11.000 IOP/s 
>>Three VM on one Host: 3x7.000 IOP/s 

And host cpu is 100% ?


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

De: "Stefan Priebe - Profihost AG" <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: Lundi 12 Novembre 2012 12:58:35 
Objet: Re: [pve-devel] less cores more iops / speed 

Am 12.11.2012 08:51, schrieb 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) 

One VM on one Host: 18.000 IOP/s 
Two VM on one Host: 2x11.000 IOP/s 
Three VM on one Host: 3x7.000 IOP/s 

> 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). 
No it doesn't scale. 

Stefan 

> ----- 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 
>