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Fri, 30 Oct 2026 13:06:26 -0700 (PDT) Received: from medusa.lab.kspace.sh ([208.88.152.253]) by smtp.googlemail.com with ESMTPSA id 5a478bee46e88-36a42a6eabbsm10272118eec.24.2026.10.30.13.05.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 13:05:58 -0700 (PDT) Date: Fri, 30 Oct 2026 13:05:50 -0700 From: Mohamed Khalfella To: Daniel Wagner Cc: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Justin Tee , Naresh Gottumukkala , Paul Ely , Hannes Reinecke , Chaitanya Kulkarni , James Smart , Randy Jennings , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 17/18] nvme: Add support for CQT to nvme host Message-ID: <20261030200550.GF122209-mkhalfella@purestorage.com> References: <20260920182936.2317916-1-mkhalfella@purestorage.com> <20260920182936.2317916-18-mkhalfella@purestorage.com> <4459053b-35eb-4359-99a6-05393a9a62d6@flourine.local> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4459053b-35eb-4359-99a6-05393a9a62d6@flourine.local> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261030_130628_578257_BCE3ED02 X-CRM114-Status: GOOD ( 18.31 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue 2026-10-20 14:46:03 +0200, Daniel Wagner wrote: > On Sun, Sep 20, 2026 at 11:28:15AM -0700, Mohamed Khalfella wrote: > > TP4129 KATO Corrections and Clarifications defined CQT (Command Quiesce > > Time) which is used along with KATO (Keep Alive Timeout) to set an upper > > limit for attempting Cross-Controller Recovery. Add ctrl->cqt, read its > > value from controller identify response, expose it via sysfs, and have > > nvme_fence_timeout_ms() account for it. > > > > Use CQT to drive time-based recovery in fc, rdma, and tcp transports. > > Add a fenced_work delayed work to each transport controller. If CCR > > fails, fencing_work switches to error recovery immediately if CQT is not > > supported. Otherwise it schedules fenced_work after the remaining fence > > timeout, which also switches to error recovery when scheduled. > > > > Signed-off-by: Mohamed Khalfella > > Reviewed-by: Hannes Reinecke > > Reviewed-by: Sagi Grimberg > > the sysfs entry needs to be documented, with this --- a/Documentation/ABI/stable/sysfs-nvme +++ b/Documentation/ABI/stable/sysfs-nvme @@ -120,6 +120,16 @@ Description: Shows the Keep Alive Timeout value in milliseconds for this controller. +What: /sys/class/nvme/nvmeX/cqt +Date: October 2026 +KernelVersion: 7.5 +Contact: Mohamed Khalfella +Description: + Shows CQT (Command Quiesce Time) in milliseconds as reported + by the Identify Controller data structure. CQT is the time the + controller needs to quiesce outstanding commands once the + host loses communication with it. + What: /sys/class/nvme/nvmeX/cmb Date: October 2016 KernelVersion: 4.9 Added the diff above to the patch. > > Reviewed-by: Daniel Wagner