Re: [PATCH] blk-mq: set default elevator as deadline in case of hctx shared tagset

[Ming Lei <ming.lei@redhat.com>]

Hello Jens,

On Tue, Apr 06, 2021 at 11:19:33AM +0800, Ming Lei wrote:
> Yanhui found that write performance is degraded a lot after applying
> hctx shared tagset on one test machine with megaraid_sas. And turns out
> it is caused by none scheduler which becomes default elevator caused by
> hctx shared tagset patchset.
> 
> Given more scsi HBAs will apply hctx shared tagset, and the similar
> performance exists for them too.
> 
> So keep previous behavior by still using default mq-deadline for queues
> which apply hctx shared tagset, just like before.
> 
> Fixes: 32bc15afed04 ("blk-mq: Facilitate a shared sbitmap per tagset")
> Reported-by: Yanhui Ma <yama@redhat.com>
> Cc: John Garry <john.garry@huawei.com>
> Cc: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Any chance to make it in 5.12 if you are fine?

Thanks,
Ming