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([2600:1700:65a0:78e0:514:7862:1503:8e4d]) by smtp.gmail.com with ESMTPSA id e65sm2522789otb.62.2019.12.12.12.32.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Dec 2019 12:32:01 -0800 (PST) Subject: Re: [RFC PATCH 0/2] nvmet: add polling support To: Chaitanya Kulkarni , "hch@lst.de" References: <20191210062557.5171-1-chaitanya.kulkarni@wdc.com> From: Sagi Grimberg Message-ID: Date: Thu, 12 Dec 2019 12:32:00 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191212_123203_957664_9C198E50 X-CRM114-Status: GOOD ( 13.51 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-nvme@lists.infradead.org" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org >> percpu threads per namespace? Sounds like the wrong approach. These >> threads will compete for cpu time with the main nvmet contexts. >> > That make sense, how about a global threadpool for target which can be > shared between all the subsystem and their name-spaces just like we > have buffered_io_wq? >> Have you considered having the main nvmet contexts incorporate polling >> activity between I/Os? Don't have a great dea on how to do it from first >> thought... >> > > I am not able to understand nvmet context, can you please elaborate ? > Are you referring to the pattern we one have in the > nvme_execute_rq_polled() ? No, we would want non-selective polling. Right now we have nvmet context starting from the transport going to submit I/O to the backend, or starting from the backend going to submit to the transport. Ideally, we'd have these contexts to do the polling instead of a different thread that will poll for as much as it can taking away cpu time? One way to do it is to place a intermediate thread that will sit between the transport and the backend but that would yield an additional context switch in the I/O path (not ideal). _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme