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[73.241.217.19]) by smtp.gmail.com with ESMTPSA id h8sm547606pfv.60.2021.06.02.17.18.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 02 Jun 2021 17:18:54 -0700 (PDT) Subject: Re: [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths To: Bean Huo , Can Guo , asutoshd@codeaurora.org, nguyenb@codeaurora.org, hongwus@codeaurora.org, linux-scsi@vger.kernel.org, kernel-team@android.com Cc: Stanley Chu , Alim Akhtar , Avri Altman , "James E.J. Bottomley" , "Martin K. Petersen" , Matthias Brugger , Bean Huo , Jaegeuk Kim , Adrian Hunter , Kiwoong Kim , Satya Tangirala , open list , "moderated list:ARM/Mediatek SoC support" , "moderated list:ARM/Mediatek SoC support" References: <1621845419-14194-1-git-send-email-cang@codeaurora.org> <1621845419-14194-3-git-send-email-cang@codeaurora.org> <6d6d296a84f1e62f65fda4d172a85bb35d9a3684.camel@gmail.com> From: Bart Van Assche Message-ID: <200da9c5-ea20-819e-2b11-7f45e8b05cbb@acm.org> Date: Wed, 2 Jun 2021 17:18:51 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <6d6d296a84f1e62f65fda4d172a85bb35d9a3684.camel@gmail.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210602_172059_259640_1ABFF875 X-CRM114-Status: GOOD ( 15.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/31/21 9:04 AM, Bean Huo wrote: > I did a UFS queue limitation test before, observed that once the > queue is full, then the active task number in the queue will get > down. For the Nvme, the scenario is the same. You can refer to the > slide 23, and slide 24 in the pdf: > https://elinux.org/images/6/6c/Linux_Storage_System_Bottleneck_Exploration_V0.3.pdf > I don't know if your patch can fix this issue. Hi Bean, That's a very interesting presentation. Unfortunately the overhead for SCSI in that presentation includes the SCSI core + UFS driver. Given the use of the host lock in the version of the UFS driver that was used to prepare that presentation, the overhead introduced by the UFS driver may be significant. Maybe someone should measure the overhead of the scsi_debug driver and compare it with the NVMe loopback driver to get a better idea of how the overhead of these two subsystems compare to each other? Bart. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel