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From: "jianchao.wang" <jianchao.w.wang@oracle.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V7 1/4] blk-mq: refactor the code of issue request directly
Date: Wed, 14 Nov 2018 17:23:48 +0800	[thread overview]
Message-ID: <17b51550-d45b-9861-b172-74ee0e256d98@oracle.com> (raw)
In-Reply-To: <20181114091153.GB20550@ming.t460p>

Hi Ming

On 11/14/18 5:11 PM, Ming Lei wrote:
>>  
>> -	if (!blk_mq_get_dispatch_budget(hctx))
>> -		goto insert;
>> +	if (unlikely(!blk_mq_get_dispatch_budget(hctx)))
>> +		goto out_unlock;
> The unlikely annotation is a bit misleading, since out-of-budget can
> happen frequently in case of low queue depth, and there are lots of
> such examples.
> 

This could be good for the case for no .get_budget and getting budget success.
In case of out-of-budget, we insert the request which is slow path.
It should be OK. Maybe some comment should be added for this.

Thanks
Jianchao



  reply	other threads:[~2018-11-14  9:23 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-14  8:45 [PATCH V7 0/4] blk-mq: refactor and fix on " Jianchao Wang
2018-11-14  8:45 ` [PATCH V7 1/4] blk-mq: refactor the code of " Jianchao Wang
2018-11-14  9:11   ` Ming Lei
2018-11-14  9:23     ` jianchao.wang [this message]
2018-11-14  9:43       ` Ming Lei
2018-11-14 15:22         ` Jens Axboe
2018-11-15  1:35           ` jianchao.wang
2018-11-14  8:45 ` [PATCH V7 2/4] blk-mq: fix issue directly case when q is stopped or quiesced Jianchao Wang
2018-11-14  9:20   ` Ming Lei
2018-11-14  9:29     ` jianchao.wang
2018-11-14  9:35       ` Ming Lei
2018-11-15  1:37         ` jianchao.wang
2018-11-14  8:45 ` [PATCH V7 3/4] blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests Jianchao Wang
2018-11-14  8:45 ` [PATCH V7 4/4] blk-mq: replace and kill blk_mq_request_issue_directly Jianchao Wang

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