From: Kaitao Cheng <kaitao.cheng@linux.dev>
To: Bart Van Assche <bvanassche@acm.org>,
Jens Axboe <axboe@kernel.dk>, Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Randy Dunlap <rdunlap@infradead.org>
Cc: linux-block@vger.kernel.org, Kaitao Cheng <chengkaitao@kylinos.cn>
Subject: Re: [PATCH] blk-mq: add direct dispatch support for mq-deadline
Date: Tue, 20 Oct 2026 20:49:03 +0800 [thread overview]
Message-ID: <95c88c33-0184-4258-ac02-8eb42f346b36@linux.dev> (raw)
In-Reply-To: <307b05d7-16dd-493a-a10a-d5ac50ec219b@acm.org>
在 2026/10/17 22:19, Bart Van Assche 写道:
> On 10/17/26 3:54 AM, Kaitao Cheng wrote:
>> Bandwidth in MiB/s:
>>
>> Workload none mq-deadline my-patch
>> jobs1-4k 1209 1047 1174
>> jobs10-4k 2458 946 2349
>> jobs1-32k 2568 2565 2562
>
> Can I conclude from the above numbers that "none" performs
> better than "mq-deadline" and hence that it's better not to use
> and I/O scheduler rather than to complicate the mq-deadline source
> code?
>
> I have removed the linux-doc and linux-kernel mailing lists from the
> Cc-list. Block layer patches should be posted on the linux-block mailing
> list only.
>
I ran additional tests on both a SATA SSD and a SAS HDD. The results are
as follows:
SATA SSD none mq-deadline my-patch
jobs1-4k 294 295 295
jobs10-4k 133 400 401
jobs1-32k 470 470 470
SAS HDD none mq-deadline my-patch
jobs1-4k 218 218 218
jobs10-4k 26.6 26.9 27.2
jobs1-32k 225 224 224
The SAS HDD results show no clear performance differences. On the SATA SSD,
however, mq-deadline outperforms none, and my patch preserves mq-deadline's
performance. Together with the earlier NVMe SSD results, these results
suggest that the patch combines the benefits of both none and mq-deadline.
I also found in the NVMe SSD tests that disabling the direct dispatch paths
used with the none scheduler causes its performance to drop to the same
level as mq-deadline.
--
Thanks
Kaitao Cheng
prev parent reply other threads:[~2026-10-20 12:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 10:54 [PATCH] blk-mq: add direct dispatch support for mq-deadline Kaitao Cheng
2026-10-17 14:19 ` Bart Van Assche
2026-10-18 9:09 ` Kaitao Cheng
2026-10-20 12:49 ` Kaitao Cheng [this message]
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