From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Zhang Subject: Re: Linux support for RDMA (was: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics) Date: Mon, 04 Apr 2005 08:56:56 -0400 Message-ID: <1112619415.2880.5.camel@localhost.localdomain> References: <67D69596DDF0C2448DB0F0547D0F947E01781F2E@yogi.asicdesigners.com> <1112576171.4227.5.camel@mylaptop> <20050404063456.GB30855@colo.lackof.org> Reply-To: mingz@ele.uri.edu Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Dmitry Yusupov , "David S. Miller" , mpm@selenic.com, andrea@suse.de, michaelc@cs.wisc.edu, James.Bottomley@HansenPartnership.com, ksummit-2005-discuss@thunk.org, netdev@oss.sgi.com Return-path: To: open-iscsi In-Reply-To: <20050404063456.GB30855@colo.lackof.org> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org yes, it travel 3 times instead of 1 time. and it is duplex. send traffic will take another 20%. so total 80% or it can never run that fast. ming On Mon, 2005-04-04 at 02:34, Grant Grundler wrote: > On Sun, Apr 03, 2005 at 05:56:11PM -0700, Dmitry Yusupov wrote: > > I do not get your concern with memory BW. With good AMD box V40Z(SUN) > > you can get 5.3GBytes/sec. Even with 10Gbps full speed you have 80% > > left. PCI-X BUS BW is bigger concern... > > Yes and No. PCI-X isn't fast enough but the data only crosses > the PCI-X bus once. Think about the data flow: > 1) DMA to RAM > 2) load into CPU cache > 3) store back into RAM > > We are down to 40% left...graphics folks won't like you. > > grant