<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Mar 9, 2006, at 7:32 PM, <A href="mailto:beowulf-request@beowulf.org">beowulf-request@beowulf.org</A> wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">Michael Will wrote:</FONT></P> <BLOCKQUOTE type="cite"><P style="margin: 0.0px 0.0px 0.0px 10.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">Infiniband with DDR is already at 20Gbps over CX4 copper</FONT></P> </BLOCKQUOTE><P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande; min-height: 16.0px"><BR></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">Over 3 meters cables thick as firehose. 5 meters if you like to play </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">with fire.</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande; min-height: 16.0px"><BR></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">There is a time when fiber is the right thing to do. However, WDM<SPAN class="Apple-converted-space"> </SPAN></FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">solutions are still expensive, it's much cheaper to use several fibers<SPAN class="Apple-converted-space"> </SPAN></FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">per cable. You can run 12.5 Gbps Ethernet over 200 meters [today] ...</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande; min-height: 16.0px"><BR></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">Patrick</FONT></P> </BLOCKQUOTE></DIV><DIV><BR class="khtml-block-placeholder"></DIV>... what he said ...<DIV><BR class="khtml-block-placeholder"></DIV><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Processor efficiency FireWire has a 32-bit "risc" type microprocessor, is peer to peer in hardware / firmware and has other lean architecture features.</DIV></BLOCKQUOTE><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Uh, is having a 32-bit CPU in your NIC supposed to make it faster or slower? In the InfiniBand space, there's a proof that having that</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">extra cpu makes small packets slower. With FireWire's slower link [microprocessor] speed ...</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Greg</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">The old "bus arbitrator" question = depends on the task at hand: small files / small packets = greater overhead = extra data in the packet frame v. data transmitted ... large files / larger packets = lesser overhead = massive data delivered v. size of packet.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">This may be at the heart of my question: which hardware protocol is optimum (for a "glass bus" ?) interconnecting multiple processors in a local network? If anyone should know this answer, the bleeding edge builders of clusters should = the members of this group.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">If everything else is equal:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">microprocessor speed / bus speed = same, same</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">parallel "bit number" = 32 bit? 64 bit?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">address space = 32 nodes? 64 nodes? 256 nodes? more?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">line length = greatest distance between node clusters = 10 feet? 100 feet? 10,000 feet?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">... which protocol would perform the best?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">If anyone should know this answer or be able to make a very well educated guess, the bleeding edge builders of Beowulf clusters should = the members of this group.</DIV><DIV><BR><DIV> <P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande">Ed Karns</P><P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande">FireWireStuff.com</P><BR class="Apple-interchange-newline"> </DIV><DIV>A meat space reference: FireWire 800 = double duplex, metal (8 wire) or glass (2 fiber) = 32 bit microprocessor (speed dependent on host bus) = 800 megabits per second = streaming, large data frame / file transfer rate = 80 MegaBytes per second ~~= 8 DVD resolution videos, bidirectionally.</DIV><DIV><BR class="khtml-block-placeholder"></DIV></DIV></BODY></HTML>