From: "Talpey, Thomas" Subject: Re: [RFC,PATCH 4/14] knfsd: has_wspace per transport Date: Thu, 17 May 2007 08:39:25 -0400 Message-ID: References: <20070516192211.GJ9626@sgi.com> <20070516211053.GE18927@fieldses.org> <20070517071202.GE27247@sgi.com> <17996.11983.278205.708747@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: nfs@lists.sourceforge.net To: Neil Brown Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list2-new.sourceforge.net with esmtp (Exim 4.43) id 1HofGd-0008Q3-IU for nfs@lists.sourceforge.net; Thu, 17 May 2007 05:39:39 -0700 Received: from mx2.netapp.com ([216.240.18.37]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1HofGf-0004P8-Ba for nfs@lists.sourceforge.net; Thu, 17 May 2007 05:39:42 -0700 In-Reply-To: <17996.11983.278205.708747@notabene.brown> References: <20070516192211.GJ9626@sgi.com> <20070516211053.GE18927@fieldses.org> <20070517071202.GE27247@sgi.com> <17996.11983.278205.708747@notabene.brown> List-Id: "Discussion of NFS under Linux development, interoperability, and testing." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfs-bounces@lists.sourceforge.net Errors-To: nfs-bounces@lists.sourceforge.net At 06:30 AM 5/17/2007, Neil Brown wrote: >And I gather by the fact that you test "->sko_has_wspace" that RDMA >doesn't have such a function? Do that mean that RDMA will never >reject a write due to lack of space? That seems unlikely. RDMA uses credits, which are preallocated per-connection resources in the hardware. RDMA transports don't generally support flow control, that is left to the upper layer. As such, if the client is obeying the protocol, the send will succeed. And if it's not, then the client only loses since the failure will cause the connection to be lost. Someday we might want to support this kind of test. There are shared resource schemes in RDMA, more for the receive side, but it's not out of the question for sends. As a default though, a NULL has_wspace makes sense. Tom. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs