Re: Very slow qemu device access

[Ming Lei]

Hello Matthew,

On Fri, Aug 07, 2020 at 06:44:16PM +0100, Matthew Wilcox wrote:
> 
> Everything starts going very slowly after this commit:
> 
> commit 37f4a24c2469a10a4c16c641671bd766e276cf9f (refs/bisect/bad)
> Author: Ming Lei <ming.lei@xxxxxxxxxx>
> Date:   Tue Jun 30 22:03:57 2020 +0800
> 
>     blk-mq: centralise related handling into blk_mq_get_driver_tag

Yeah, the above is one known bad commit, which is reverted in
4e2f62e566b5 ("Revert "blk-mq: put driver tag when this request is completed")

Finally the fixed patch of 'blk-mq: centralise related handling into blk_mq_get_driver_tag'
is merged as 568f27006577 ("blk-mq: centralise related handling into blk_mq_get_driver_tag").

So please test either 4e2f62e566b5 or 568f27006577 and see if there is
such issue.


Thanks,
Ming