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Thu, 20 Apr 2023 12:34:41 -0700 (PDT) Received: from c7-smtp.dev.purestorage.com ([2620:125:9007:320:7:32:106:0]) by smtp-relay.gmail.com with ESMTPS id y7-20020a0cec07000000b005dd8b74b9easm189733qvo.26.2023.04.20.12.34.41 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Apr 2023 12:34:41 -0700 (PDT) X-Relaying-Domain: purestorage.com Received: from dev-ushankar.dev.purestorage.com (dev-ushankar.dev.purestorage.com [IPv6:2620:125:9007:640:7:70:36:0]) by c7-smtp.dev.purestorage.com (Postfix) with ESMTP id 2176920950; Thu, 20 Apr 2023 13:34:40 -0600 (MDT) Received: by dev-ushankar.dev.purestorage.com (Postfix, from userid 1557716368) id 1CF00E42E74; Thu, 20 Apr 2023 13:34:40 -0600 (MDT) Date: Thu, 20 Apr 2023 13:34:39 -0600 From: Uday Shankar To: Sagi Grimberg Cc: Costa Sapuntzakis , Randy Jennings , Hannes Reinecke , Keith Busch , Christoph Hellwig , Jens Axboe , linux-nvme@lists.infradead.org Subject: Re: [PATCH 3/3] nvme: improve handling of long keep alives Message-ID: <20230420193439.GA3766288@dev-ushankar.dev.purestorage.com> References: <20230417225558.2890062-1-ushankar@purestorage.com> <20230417225558.2890062-4-ushankar@purestorage.com> <8c3c82ba-2551-487a-4593-b9369e5ccfb0@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8c3c82ba-2551-487a-4593-b9369e5ccfb0@grimberg.me> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230420_123444_168717_66688708 X-CRM114-Status: GOOD ( 12.93 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Apr 18, 2023 at 07:59:51PM +0300, Sagi Grimberg wrote: > Is this something that was met in reality? > > it is surprising that host->ctrl is super fast and > ctrl->host is super slow to the extent that this > situation exists in reality... We haven't seen this exact issue in reality, but we more generally have observed significant delays in host-side keep alive processing with controllers that do not support TBKA. This patch should help with that issue.