Subject: which IO-scheduler is best for flash based storage device with ext4

Hi,

Could you tell me which IO-scheduler is best for flash based storage device with ext4 ?
Just search from WWW, I saw it is said that the noop is best because the CFQ is design for the mechanical hard disk.
And I did the performance test with IOzone between the IO-scheduler noop and cfq. The performance difference is small.
So here I want to get some answer from you about this question.

Thanks.
Huang weller




2016-01-13 09:06:02

by Jan Kara

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Subject: Re: which IO-scheduler is best for flash based storage device with ext4

Hi,

On Wed 13-01-16 06:33:28, HUANG Weller (CM/ESW12-CN) wrote:
> Could you tell me which IO-scheduler is best for flash based storage
> device with ext4 ? Just search from WWW, I saw it is said that the noop
> is best because the CFQ is design for the mechanical hard disk. And I
> did the performance test with IOzone between the IO-scheduler noop and
> cfq. The performance difference is small. So here I want to get some
> answer from you about this question.

Yes, CFQ is meant for classical rotational disk. For normal SSDs I use
deadline IO scheduler (it does more request merging, prefers read over
writes), for high-end I'd use noop.

Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR