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Subject: Re: [PATCH v5 00/14] blk-mq: Reduce static requests memory footprint
 for shared sbitmap
To:     Bart Van Assche <bvanassche@acm.org>,
        Kashyap Desai <kashyap.desai@broadcom.com>,
        Jens Axboe <axboe@kernel.dk>
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        <ming.lei@redhat.com>, <hare@suse.de>,
        <linux-scsi@vger.kernel.org>, Jan Kara <jack@suse.cz>
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From:   John Garry <john.garry@huawei.com>
Message-ID: <0da031cb-427b-abd8-368d-d242e8c844c8@huawei.com>
Date:   Fri, 8 Oct 2021 09:07:25 +0100
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On 08/10/2021 04:11, Bart Van Assche wrote:

+

> On 10/7/21 13:31, Kashyap Desai wrote:
>> I tested this patchset on 5.15-rc4 (master) -
>> https://github.com/torvalds/linux.git
>>
>> #1 I noticed some performance regression @mq-deadline scheduler which 
>> is not
>> related to this series. I will bisect and get more detail about this 
>> issue
>> separately.
> 
> Please test this patch series on top of Jens' for-next branch 
> (git://git.kernel.dk/linux-block). The mq-deadline performance on Jens' 
> for-next branch should match that of kernel v5.13.

Kashyap did also mention earlier that he say the drop from v5.11 -> v5.12.

The only thing I saw possibly related there was Jan's work in 
https://lore.kernel.org/linux-block/20210111164717.21937-1-jack@suse.cz/
to fix a performance regression witnessed on megaraid sas for slower media.

But I quite doubtful that this is the issue.

Thanks,
John