Re: [REVIEW] NVM Express driver

[Matthew Wilcox]

On Fri, Mar 04, 2011 at 08:06:45AM -0500, Christoph Hellwig wrote:
> What's the reason to make this a make_request based driver?  That loses
> all the intelligence that has been put into the queueing layer, like I/O
> bandwith controlling and fair scheduling.  Is it just queue_lock
> contention?  If so it would be great if you could help with testing
> Jens' stack-plug and request allocation scalability patches.

The hardware has the ability to do I/O bandwidth control and fair
scheduling (albeit on a fairly coarse granularity).  By doing it in
software, all we're doing for these devices is increasing I/O latency
and burning CPU cycles.
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