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([2601:647:4802:9070:b58b:5460:6ed2:8ff9]) by smtp.gmail.com with ESMTPSA id in12sm3573550pjb.29.2020.08.11.13.53.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 Aug 2020 13:53:06 -0700 (PDT) Subject: Re: [PATCH v2 0/3] reduce quiesce time for lots of name spaces To: Chao Leng , Ming Lei References: <20200807090559.29582-1-lengchao@huawei.com> <20200807134932.GA2122627@T590> <61a78a78-73aa-1c67-1e8c-eae8f7c3a4e0@huawei.com> <20200810031547.GB2202641@T590> <6dc6bb01-5bfd-bf13-f53a-1bc75a6b3991@huawei.com> From: Sagi Grimberg Message-ID: <4dbd5fe2-b3df-dec5-81f2-6ff97472f62a@grimberg.me> Date: Tue, 11 Aug 2020 13:53:04 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <6dc6bb01-5bfd-bf13-f53a-1bc75a6b3991@huawei.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200811_165309_636908_01E4BD31 X-CRM114-Status: GOOD ( 14.50 ) 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-block@vger.kernel.org, kbusch@kernel.org, axboe@fb.com, linux-nvme@lists.infradead.org, hch@lst.de 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 >>> About using per_cpu to replace SRCU, I suggest separate discussion. >>> Can you show the patch? This will make it easier to discuss. >> https://lore.kernel.org/linux-block/20200728134938.1505467-1-ming.lei@redhat.com/ >> > Directly replace SRCU with percpu_ref, is not safe. > This may make quiesce queue wait extra time, in extreme scenario, > maybe wait for ever. Agree with Ming that this is not necessarily pressing as this issue existed in nvme for a long time. I don't resist to change the locking mechanism, but Ming needs to provide evidence that this change does not degrade reliability nor performance. Personally I'd like to see this specific issue solved first and then do a an infrastructure change. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme