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" <[email protected]>
À: "Stefan Priebe - Profihost AG" <[email protected]>
Cc: [email protected]
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" <[email protected]>
À: "Alexandre DERUMIER" <[email protected]>
Cc: "eric" <[email protected]>, [email protected]
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" <[email protected]>
À: "Alexandre DERUMIER" <[email protected]>
Cc: "eric" <[email protected]>, [email protected]
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" <[email protected]>
À: "Alexandre DERUMIER" <[email protected]>
Cc: "eric" <[email protected]>, [email protected]
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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