Re: [Qemu-devel] [RFC] Replace posix-aio with custom thread pool

[Avi Kivity]

Gerd Hoffmann wrote:
> Well, I see a massive slowdown when switching from sync to aio in the
> xen backend code.  I think the reason is that due to the lack of a
> vectored interface (and thus /me submitting separate aio requests for
> each iovec element) stuff gets parallelized *way* too much and disk seek
> times are killing me.
>   

Try switching to the deadline io scheduler.  cfq has a known issue with 
this.

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