RE: [PATCH v2] blk-mq: Fix blk_mq_tagset_busy_iter() for shared tags

[Kashyap Desai]

> -----Original Message-----
> From: John Garry [mailto:john.garry@xxxxxxxxxx]
> Sent: Monday, October 18, 2021 3:11 PM
> To: axboe@xxxxxxxxx
> Cc: ming.lei@xxxxxxxxxx; linux-block@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; kashyap.desai@xxxxxxxxxxxx; hare@xxxxxxx; John
> Garry <john.garry@xxxxxxxxxx>
> Subject: [PATCH v2] blk-mq: Fix blk_mq_tagset_busy_iter() for shared
tags
>
> Since it is now possible for a tagset to share a single set of tags, the
iter
> function should not re-iter the tags for the count of #hw queues in that
case.
> Rather it should just iter once.
>
> Fixes: e0fdf846c7bb ("blk-mq: Use shared tags for shared sbitmap
support")
> Reported-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
> Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> Diff to v1:
> - Add Ming's RB tag

Now I noticed proper host_busy in my test. Still CPU hogging is not
resolved, but issue addressed by this patch is resolved.

Tested-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>

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