Messages in this thread | | | Subject | Re: [PATCH 00/14] introduce the BFQ-v0 I/O scheduler as an extra scheduler | From | Jens Axboe <> | Date | Wed, 26 Oct 2016 09:32:36 -0600 |
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On 10/26/2016 09:29 AM, Christoph Hellwig wrote: > On Wed, Oct 26, 2016 at 05:13:07PM +0200, Arnd Bergmann wrote: >> The question to ask first is whether to actually have pluggable >> schedulers on blk-mq at all, or just have one that is meant to >> do the right thing in every case (and possibly can be bypassed >> completely). > > That would be my preference. Have a BFQ-variant for blk-mq as an > option (default to off unless opted in by the driver or user), and > not other scheduler for blk-mq. Don't bother with bfq for non > blk-mq. It's not like there is any advantage in the legacy-request > device even for slow devices, except for the option of having I/O > scheduling.
It's the only right way forward. blk-mq might not offer any substantial advantages to rotating storage, but with scheduling, it won't offer a downside either. And it'll take us towards the real goal, which is to have just one IO path. Adding a new scheduler for the legacy IO path makes no sense. Adding one for blk-mq and phasing out the old path is what we need to do.
-- Jens Axboe
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