Re: [PATCH] cfq-iosched: non-rot devices do not need queue merging

From: Jens Axboe
Date: Wed Dec 30 2009 - 13:45:47 EST


On Wed, Dec 30 2009, Corrado Zoccolo wrote:
> Non rotational devices' performances are not affected by
> distance of requests, so there is no point in having overhead
> to merge queues of nearby requests.

If the distance is zero, it may still make a big difference (at least
for writes). This check would be better as "ncq and doesn't suck", ala

blk_queue_nonrot(q) && tagged

like we do elsewhere.

--
Jens Axboe

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