# RE: \[PATCH v5 00/14\] blk-mq: Reduce static requests memory footprint for shared sbitmap

- From: Kashyap Desai \<kashyap.desai@broadcom.com\>
- Date: 2021-10-05 14:03:42 
- List: linux-block
- Page: https://ratatoskr.run/linux-block/2021/10/1531601
- Thread: https://ratatoskr.run/linux-block/2021/10/1531231/t.md

```text
> -----Original Message-----
> From: John Garry [mailto:<redacted>]
> Sent: Tuesday, October 5, 2021 7:05 PM
> To: Jens Axboe <axboe@kernel.dk>; kashyap.desai@broadcom.com
> Cc: <redacted>; <redacted>;
> ming.lei@redhat.com; hare@suse.de; linux-scsi@vger.kernel.org
> Subject: Re: [PATCH v5 00/14] blk-mq: Reduce static requests memory
> footprint for shared sbitmap
>
> On 05/10/2021 13:35, Jens Axboe wrote:
> >> Baseline is 1b2d1439fc25 (block/for-next) Merge branch
> >> 'for-5.16/io_uring'
> >> into for-next
> > Let's get this queued up for testing, thanks John.
>
> Cheers, appreciated
>
> @Kashyap, You mentioned that when testing you saw a performance
> regression from v5.11 -> v5.12 - any idea on that yet? Can you describe
> the
> scenario, like IO scheduler and how many disks and the type? Does
> disabling
> host_tagset_enable restore performance?

John - I am still working on this. System was not available due to some
other debugging.

>
>  From checking differences between those kernels, I don't see anything
> directly relevant in sbitmap support or in the megaraid sas driver.
>
> Thanks,
> John
```

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