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[95.91.253.215]) by smtp.googlemail.com with ESMTPSA id p10sm4150690wme.30.2021.08.02.08.24.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Aug 2021 08:24:42 -0700 (PDT) Message-ID: <779aae9841331229e29fd3be23de55cec776af16.camel@gmail.com> Subject: Re: [PATCH v3 11/18] scsi: ufs: Revert "Utilize Transfer Request List Completion Notification Register" From: Bean Huo To: Bart Van Assche , "Martin K . Petersen" Cc: linux-scsi@vger.kernel.org, Jaegeuk Kim , Adrian Hunter , Stanley Chu , Can Guo , Asutosh Das , Avri Altman , "James E.J. Bottomley" , Matthias Brugger , Bean Huo , Kiwoong Kim , Keoseong Park , Caleb Connolly , "Gustavo A. R. Silva" Date: Mon, 02 Aug 2021 17:24:41 +0200 In-Reply-To: <20210722033439.26550-12-bvanassche@acm.org> References: <20210722033439.26550-1-bvanassche@acm.org> <20210722033439.26550-12-bvanassche@acm.org> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Wed, 2021-07-21 at 20:34 -0700, Bart Van Assche wrote: > Using the UTRLCNR register involves two MMIO accesses in the hot path > while > using the doorbell register only involves a single MMIO access. Since > MMIO > accesses take time, do not use the UTRLCNR register. The spinlock > contention > on the SCSI host lock that is reintroduced by this patch will be > addressed > by a later patch. > > This reverts commit 6f7151729647e58ac7c522081255fd0c07b38105. > > Cc: Adrian Hunter > Cc: Stanley Chu > Cc: Can Guo > Cc: Asutosh Das > Cc: Avri Altman > Signed-off-by: Bart Van Assche > Hi Bart, I did the comparison test on my platform, it is very difficult to get a very clear and fair result between two changes. but lamely speaking, on the small chunk size read/write, your changes wins. but on the big chunk size, It is not very clear, the gap between the two changes can be ignored. Tested-by: Bean Huo Bean