[pve-devel] less cores more iops / speed

[Stefan Priebe - Profihost AG]

Am 12.11.2012 15:26, schrieb Alexandre DERUMIER:
> Maybe some tracing on kvm process could give us clues to find where the cpu is used ?
>
> Also another idea, can you try with "auth supported=none" ? maybe they are some overhead with ceph authenfication ?

ceph.conf on all ceph hosts:
[global]
         auth cluster required = cephx
         auth service required = cephx
         auth client required = cephx
         keyring = /etc/ceph/$name.keyring

So i just need to add auth supported=none on all ceph hosts?

Stefan

> ----- Mail original -----
>
> De: "Alexandre DERUMIER" <aderumier at odiso.com>
> À: "Stefan Priebe - Profihost AG" <s.priebe at profihost.ag>
> Cc: pve-devel at pve.proxmox.com
> Envoyé: Lundi 12 Novembre 2012 15:20:07
> Objet: Re: [pve-devel] less cores more iops / speed
>
> 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
>>>
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