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[66.29.188.166]) by smtp.gmail.com with ESMTPSA id h134sm9513067pfe.27.2018.11.28.04.54.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 28 Nov 2018 04:54:06 -0800 (PST) Subject: Re: [PATCH 3/8] blk-mq: add mq_ops->commit_rqs() To: Christoph Hellwig Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org References: <20181126163556.5181-1-axboe@kernel.dk> <20181126163556.5181-4-axboe@kernel.dk> <20181128071601.GA11774@infradead.org> From: Jens Axboe Message-ID: Date: Wed, 28 Nov 2018 05:54:04 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181128071601.GA11774@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 11/28/18 12:16 AM, Christoph Hellwig wrote: > On Mon, Nov 26, 2018 at 09:35:51AM -0700, Jens Axboe wrote: >> blk-mq passes information to the hardware about any given request being >> the last that we will issue in this sequence. The point is that hardware >> can defer costly doorbell type writes to the last request. But if we run >> into errors issuing a sequence of requests, we may never send the request >> with bd->last == true set. For that case, we need a hook that tells the >> hardware that nothing else is coming right now. >> >> For failures returned by the drivers ->queue_rq() hook, the driver is >> responsible for flushing pending requests, if it uses bd->last to >> optimize that part. This works like before, no changes there. >> >> Signed-off-by: Jens Axboe > > This looks fine, but normally I would only add the method together with > the actual user.. I included the two hunks from patch 7 in this one, so there's a real use (and fix) with it. -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 From: axboe@kernel.dk (Jens Axboe) Date: Wed, 28 Nov 2018 05:54:04 -0700 Subject: [PATCH 3/8] blk-mq: add mq_ops->commit_rqs() In-Reply-To: <20181128071601.GA11774@infradead.org> References: <20181126163556.5181-1-axboe@kernel.dk> <20181126163556.5181-4-axboe@kernel.dk> <20181128071601.GA11774@infradead.org> Message-ID: On 11/28/18 12:16 AM, Christoph Hellwig wrote: > On Mon, Nov 26, 2018@09:35:51AM -0700, Jens Axboe wrote: >> blk-mq passes information to the hardware about any given request being >> the last that we will issue in this sequence. The point is that hardware >> can defer costly doorbell type writes to the last request. But if we run >> into errors issuing a sequence of requests, we may never send the request >> with bd->last == true set. For that case, we need a hook that tells the >> hardware that nothing else is coming right now. >> >> For failures returned by the drivers ->queue_rq() hook, the driver is >> responsible for flushing pending requests, if it uses bd->last to >> optimize that part. This works like before, no changes there. >> >> Signed-off-by: Jens Axboe > > This looks fine, but normally I would only add the method together with > the actual user.. I included the two hunks from patch 7 in this one, so there's a real use (and fix) with it. -- Jens Axboe