From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH] An argument for allowing applications to manually send RMPP packets if desired Date: Mon, 12 Sep 2011 11:23:35 -0600 Message-ID: <20110912172334.GC18574@obsidianresearch.com> References: <4C2744E8AD2982428C5BFE523DF8CDCB4A5387E899@MNEXMB1.qlogic.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roland Dreier Cc: Mike Heinz , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Todd Rimmer List-Id: linux-rdma@vger.kernel.org On Mon, Sep 12, 2011 at 10:15:08AM -0700, Roland Dreier wrote: > > But is this really needed? Consider that these 3,000 replies only > > differ in their destination addresses - the actual data is > > identical in all of them. Moreover, the data returned for a query > > like this changes only rarely in a production fabric - which means > > that the response could be generated once and then and then > > re-used to provide responses to multiple clients. > > > > To allow this, however, the SM must be allowed to explicitly > > manage its own RMPP transmissions instead of sending each response > > as a complete unit. If this is allowed, then the kernel no longer > > needs to allocate large amounts of buffer space, and the SM can > > build the results of certain queries in advance, updating them > > only when the fabric changes, instead of recreating them each time > > it receives an IB_MAD_METHOD_GET_TABLE. > > It seems at least the SM side could be handled using writev() to > splice together the data it wants to send. How does that help avoid the kernel memory allocations? I think having the option for RMPP in user space is a good idea, it allows much more efficiency on the SM side.. 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