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[66.29.188.166]) by smtp.gmail.com with ESMTPSA id p7sm2872275pfa.22.2018.12.06.19.16.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Dec 2018 19:16:22 -0800 (PST) Subject: Re: [PATCH V11 0/4] blk-mq: refactor code of issue directly To: Jianchao Wang Cc: ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1544152185-32667-1-git-send-email-jianchao.w.wang@oracle.com> From: Jens Axboe Message-ID: Date: Thu, 6 Dec 2018 20:16:20 -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: <1544152185-32667-1-git-send-email-jianchao.w.wang@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/6/18 8:09 PM, Jianchao Wang wrote: > Hi Jens > > Please consider this patchset for 4.21. > > It refactors the code of issue request directly to unify the interface > and make the code clearer and more readable. > > This patch set is rebased on the recent for-4.21/block and add the 1st > patch which inserts the non-read-write request to hctx dispatch > list to avoid to involve merge and io scheduler when bypass_insert > is true, otherwise, inserting is ignored, BLK_STS_RESOURCE is returned > and the caller will fail forever. > > The 2nd patch refactors the code of issue request directly to unify the > helper interface which could handle all the cases. > > The 3rd patch make blk_mq_sched_insert_requests issue requests directly > with 'bypass' false, then it needn't to handle the non-issued requests > any more. > > The 4th patch replace and kill the blk_mq_request_issue_directly. Sorry to keep iterating on this, but let's default to inserting to the dispatch list if we ever see busy from a direct dispatch. I'm fine with doing that for 4.21, as suggested by Ming, I just didn't want to fiddle with it for 4.20. This will prevent any merging on the request going forward, which I think is a much safer default. You do this already for some cases. Let's do it unconditionally for a request that was ever subjected to ->queue_rq() and we didn't either error or finish after the fact. -- Jens Axboe