Messages in this thread | | | Date | Fri, 14 Mar 2014 05:44:57 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH 1/1] block: rework flush sequencing for blk-mq |
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On Fri, Mar 14, 2014 at 10:30:53AM +0100, Hannes Reinecke wrote: > That was actually one of my plans, move dm-multipath over to use > blk-mq. But then I'd need to discuss with Jens et al how to best > achieve this; the current static hctx allocation doesn't play well > with multipaths dynamic path management.
I'd say it the other way around: the clone + insert hacks in dm-multipath don't work well with blk-mq. Not allowing non-owned requests is fundamentally part of the blk-mq model to allow things like the integrated tag allocator and queue depth limiting or the preallocated driver specific data.
Instead dm-multipath should alway resubmit the request like it already does for the slow path for the first step. Longer term we might be able to operate using a cheaper temporary structure, but I'm not sure that's going to be worth it.
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