From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH 0/2] Get rid of transport layer retry count config parameter Date: Wed, 22 Jun 2016 19:31:59 +0300 Message-ID: <576ABD7F.1030204@grimberg.me> References: <1466597161-5242-1-git-send-email-sagi@grimberg.me> <20160622161559.GA18361@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160622161559.GA18361-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig Cc: linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org >> This parameter was added in order to support a proper timeout for >> error recovery before the spec defined a periodic keep-alive. >> >> Now that we have periodic keep-alive, we don't need a user configurable >> transport layer retry count, the keep-alive timeout is sufficient, >> transports can retry for as long as they see fit. > > Isn't there some IB protocol level rationale for a low retry count > in various fabric setups? None that I know of... The QP retry count determines the time it would take to fail a send/read/write.. The retry_count value is multiplied with the packet timeout (which is a result of an IB specific computation - managed by the CM). It's useful when one needs to limit the time until a send fails in order to kick error recovery (useful for srp which doesn't implement periodic keep-alive), but since nvme does, I don't see the reason why RDMA or any other transport should expose this configuration as the keep-alive timeout exists for that. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html