On 18/10/2021 19:49, Kashyap Desai wrote:

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-----Original Message-----
From: John Garry [mailto:john.garry@huawei.com]
Sent: Monday, October 18, 2021 3:11 PM
To:axboe@kernel.dk
Cc:ming.lei@redhat.com;linux-block@vger.kernel.org; linux-
kernel@vger.kernel.org;kashyap.desai@broadcom.com;hare@suse.de; John
Garry[off-list ref]
Subject: [PATCH v2] blk-mq: Fix blk_mq_tagset_busy_iter() for shared

tags

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Since it is now possible for a tagset to share a single set of tags, the

iter

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function should not re-iter the tags for the count of #hw queues in that

case.

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Rather it should just iter once.

Fixes: e0fdf846c7bb ("blk-mq: Use shared tags for shared sbitmap

support")

quoted

Reported-by: Kashyap Desai<kashyap.desai@broadcom.com>
Signed-off-by: John Garry<redacted>
Reviewed-by: Ming Lei<redacted>
---
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@broadcom.com>

Hi Jens,

Can you kindly consider picking up this patch?

I'm still waiting for feedback from Kashyap on whether we should 
optimize the other iter functions for shared tags, but this one is a fix.

Thanks!