From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH] libibverbs/doc: clarify selective signaling (Re: using IBV_SEND_SIGNALED) Date: Tue, 30 Nov 2010 11:57:44 -0700 Message-ID: <20101130185744.GK16788@obsidianresearch.com> References: <4CF3DDF0.2070907@opengridcomputing.com> <4CF3E5FA.6010308@opengridcomputing.com> <4CF4E65D.4070205@Voltaire.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4CF4E65D.4070205-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz Cc: Roland Dreier , Steve Wise , "Robert D. Russell" , linux-rdma List-Id: linux-rdma@vger.kernel.org On Tue, Nov 30, 2010 at 01:56:13PM +0200, Or Gerlitz wrote: > Steve Wise wrote: > > On 11/29/2010 11:34 AM, Robert D. Russell wrote: > > See section 8.2.1 of the iWARP Verbs draft at: > > http://tools.ietf.org/html/draft-hilland-rddp-verbs-00#section-8.2.1. > > The last big paragraph in 8.2.1 spells it all out. > > There should be a similar requirement in the IBTA IB Verbs specification... > > Yes, I think the below patch to the man page can help people > understand how to work with the thing I think the subtly here is that remote completion of a local WR does not indiciate local completion. This is the only operational case I can think of that might break the rules. For instance a protocol that had remote acks for all SENDs might be tempted to not ever use signaled WR's on the local side - since receiving the remote ACK SEND must indicate the local SEND WR is complete. This is the incorrect assumption. So, I'd suggest this language: Applications which use selective signaling can only assume that unsignaled WRs are complete once a completion for a later signaled WR is received. In practice this means that a signaled WR must be used periodically, and that the send queue should never be filled with unsignaled WRs. Jason -- 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