linux-kernel - Re: [PATCH] blk-mq: determine in advance whether batch alloc can be performed

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Message-ID: <84ad96a6-2dcd-2a5d-f526-74484324ee79@linux.alibaba.com>
Date:   Sat, 27 Aug 2022 21:10:50 +0800
From:   Liu Song <liusong@...ux.alibaba.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] blk-mq: determine in advance whether batch alloc can be
 performed


On 2022/8/26 21:33, Jens Axboe wrote:
> On 8/25/22 7:26 PM, Liu Song wrote:
>> From: Liu Song <liusong@...ux.alibaba.com>
>>
>> Some conditions for judging whether batch alloc can be performed are
>> included in "blk_mq_get_tags", and this function is only used by
>> "__blk_mq_alloc_requests_batch".
>>
>> This patch introduced a helper "can_do_batch_alloc" to prepend the
>> judgment condition and avoid unnecessary function calls.
> Curious if you saw any differences from this? Or do you just consider
> it a cleanup?
>
Hi

This patch aggregates the judgment conditions for whether batch alloc 
can be used,
which can be considered as clean up.

If it can be determined at the first judgment that batch alloc cannot be 
used, the
overhead of calling "blk_mq_get_tags" once will be reduced, are some 
differences.


Thanks