Re: About sbitmap_bitmap_show() and cleared bits (was Re: [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap)

Hannes Reinecke
2020-06-30T06:33:07Z

On 6/29/20 5:32 PM, John Garry wrote:
> Hi all,
>
> I noticed that sbitmap_bitmap_show() only shows set bits and does not
> consider cleared bits. Is that the proper thing to do?
>
> I ask, as from trying to support sbitmap_bitmap_show() for hostwide
> shared tags feature, we currently use blk_mq_queue_tag_busy_iter() to
> find active requests (and associated tags/bits) for a particular hctx.
> So, AFAICT, would give a change in behavior for sbitmap_bitmap_show(),
> in that it would effectively show set and not cleared bits.
>
Why would you need to do this?
Where would be the point traversing cleared bits?

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
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