[pve-devel] less cores more iops / speed

[Alexandre DERUMIER]

Ok thanks. 

Seem to use a lot of cpu vs nfs,iscsi ...

I hope that ceph dev will work on this soon !


----- 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 15:05:08 
Objet: Re: [pve-devel] less cores more iops / speed 

Am 12.11.2012 13:49, schrieb 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% ? 

No. For three VMs yes. For one and two no. I think librbd / rbd 
implementation in kvm is the bottleneck here. 

Stefan 

> ----- 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 
>>