From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: IB/cma: Make timeout dependent on the subnet timeout Date: Fri, 25 Apr 2014 18:21:58 +0200 Message-ID: <535A8BA6.4090603@acm.org> References: <53566BB5.5030203@acm.org> <1828884A29C6694DAF28B7E6B8A82373992F2F15@ORSMSX109.amr.corp.intel.com> <5357B25D.2000108@dev.mellanox.co.il> <5357B626.8050209@acm.org> <1828884A29C6694DAF28B7E6B8A82373992F32A2@ORSMSX109.amr.corp.intel.com> <5358BF9D.4030409@mellanox.com> <1828884A29C6694DAF28B7E6B8A82373992F4F6E@ORSMSX109.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1828884A29C6694DAF28B7E6B8A82373992F4F6E-P5GAC/sN6hkd3b2yrw5b5LfspsVTdybXVpNB7YpNyf8@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Hefty, Sean" , Or Gerlitz Cc: Hal Rosenstock , Roland Dreier , linux-rdma List-Id: linux-rdma@vger.kernel.org On 04/25/14 04:59, Hefty, Sean wrote: >> Sean, can't we have CMA to follow the same practice used in the CM where >> we derive the RC QP timeout based on the packet life time retrieved in >> path queries? e.g base the cm response time out on this value too? > > We could. The timeout that's being modified by the patch is the time needed > by the remote peer to process the incoming message and send a response. This > time is in addition to the packet life time value that gets used. > > For a remote kernel agent, the time needed to respond to a CM message may be > fairly small. For a user space client, the time may be significant, on the > order to seconds to minutes. We can probably make due with a fairly short > timeout, provided that MRAs are used by the remote side. > > There's no great solution that I can think of. Maybe the RDMA CM can adjust > the timeout based on the remote address, assuming that it can determine if > the remote address is a user space or kernel agent. Another possible approach is to make the CM timeout configurable for kernel clients only. How about creating two versions of struct rdma_conn_param - the existing version for communication between user space and kernel and a second version for in-kernel clients only ? In that second version a field could be added that allows to specify the CM timeout. Bart. -- 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