linux-kernel - Re: [PATCH v2] blk-mq: check on cpu id when there is only one ctx mapping

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Message-ID: <af5df07e-f93f-9588-4fdb-b89b37aa28a1@baylibre.com>
Date:   Wed, 31 May 2023 11:40:04 +0200
From:   Alexandre Mergnat <amergnat@...libre.com>
To:     Ed Tsai <ed.tsai@...iatek.com>, axboe@...nel.dk
Cc:     kbusch@...nel.org, liusong@...ux.alibaba.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, wsd_upstream@...iatek.com,
        peter.wang@...iatek.com, stanley.chu@...iatek.com,
        powen.kao@...iatek.com, alice.chao@...iatek.com,
        naomi.chu@...iatek.com
Subject: Re: [PATCH v2] blk-mq: check on cpu id when there is only one ctx
 mapping

On 31/05/2023 10:38, Ed Tsai wrote:
> commit f168420 ("blk-mq: don't redirect completion for hctx withs only
> one ctx mapping") When nvme applies a 1:1 mapping of hctx and ctx, there
> will be no remote request.
> 
> But for ufs, the submission and completion queues could be asymmetric.
> (e.g. Multiple SQs share one CQ) Therefore, 1:1 mapping of hctx and
> ctx won't complete request on the submission cpu. In this situation,
> this nr_ctx check could violate the QUEUE_FLAG_SAME_FORCE, as a result,
> check on cpu id when there is only one ctx mapping.

Reviewed-by: Alexandre Mergnat <amergnat@...libre.com>

-- 
Regards,
Alexandre