[pve-devel] default I/O scheduler - CFQ or Deadline?

Stanislav German-Evtushenko ginermail at gmail.com
Wed May 8 16:56:28 CEST 2013


>> If I remember, some openvz features works only with cfq ? (ionice, openvz IO
>> priorities)
>> see:
>> http://pve.proxmox.com/pipermail/pve-devel/2012-March/002488.html
>
> Yes, but we measure incredible bad performance with cfq. We get fsync
> rates of 250 instead of 3000 on ext4 (factor 12!). So iopriorities makes no
> sense if you are already 10 time slower?

Could you share the test conditions?
I tried to reproduce on:
1) Hardware RAID 0+1 with write cache and BBU + ext3, "dbench -t 60
50" resulted with the "deadline" just a bit faster
2) HDD 500GB (Desktop system) + ext4, "dbench -t 60 50" resulted with
almost no difference between CFQ and DEADLINE

Best regards,
Stanislav


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