Re: Higher than expected disk write(2) latency

[Martin Sustrik]

Hi Alan,

> > What we see is that AIO performs rather bad while we are still 
> > enqueueing more writes (it misses right position on the disk and has to 
> > do superfluous disk revolvings), however, once we stop enqueueing new 
> > write request, those already in the queue are processed swiftly.
>
> Which disk scheduler are you using - some of the disk schedulers
> intentionally delay writes to try and get better block merging.

It's CFQ. Does it delay writes? And if so, what should we use instead?

Thanks.
Martin
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