From mboxrd@z Thu Jan 1 00:00:00 1970 From: Or Gerlitz Subject: [PATCH] libibverbs/doc: clarify selective signaling (Re: using IBV_SEND_SIGNALED) Date: Tue, 30 Nov 2010 13:56:13 +0200 Message-ID: <4CF4E65D.4070205@Voltaire.com> References: <4CF3DDF0.2070907@opengridcomputing.com> <4CF3E5FA.6010308@opengridcomputing.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4CF3E5FA.6010308-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roland Dreier Cc: Steve Wise , "Robert D. Russell" , linux-rdma List-Id: linux-rdma@vger.kernel.org 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 >>> You must signal one WR for every SQ-depth worth of WRs posted. IE: >>> If your SQ depth is 16, you must signal at least one out of every 16 >>> This ensures proper flow control for HW resources. clarify selective signaling usage Signed-off-by: Or Gerlitz --- man/ibv_post_send.3 | 6 ++++++ 1 file changed, 6 insertions(+) Index: libibverbs/man/ibv_post_send.3 =================================================================== --- libibverbs.orig/man/ibv_post_send.3 +++ libibverbs/man/ibv_post_send.3 @@ -112,6 +112,12 @@ request is fully executed and a work com from the corresponding completion queue (CQ). However, if the IBV_SEND_INLINE flag was set, the buffer can be reused immediately after the call returns. +.PP +Applications which use selective signaling should make sure to post +a signaled WR (i.e one for which the IBV_SEND_SIGNALED flag is set) from +time to time - depending on the requirements of the underlying rdma device. +Typically the number of consecutive unsignaled WRs should not exceed the +size of the send queue specified when the QP was created. .SH "SEE ALSO" .BR ibv_create_qp (3), .BR ibv_create_ah (3), -- 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