<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Eh,<div>thanks for doing this and posting the results. Its very helpful.</div><div>Magali</div><div><br><div><div>On Feb 22, 2010, at 10:22 AM, Eh Tan wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Walter Landry wrote:<br><blockquote type="cite">Finally, memory pressure may have an effect. The AMD's generally have<br></blockquote><blockquote type="cite">better memory performance, but there is more contention since there<br></blockquote><blockquote type="cite">are 16 cores accessing the same memory, rather than 4 cores accessing<br></blockquote><blockquote type="cite">4 separate banks of memory.<br></blockquote><blockquote type="cite"><br></blockquote><br>The memory pressure (bandwidth limit) is indeed a major bottleneck for <br>CitcomCU and CitcomS. Generally, FEM codes require high memory bandwidth <br>to solve the sparse matrix inversion. Longstar machine has two dual-core <br>CPUs, and Ranger machine has four quad-core CPUs. All cores in the CPU <br>share the same memory bandwidth. As a result, Ranger has effectively <br>half memory bandwidth per core, compared to Longstar. This can affect <br>the speed by 5-10%.<br><br>I've done a speed benchmark showing the effect of memory bandwidth on <br>our cluster, which has two quad-core CPUs.<br><a href="http://www.geodynamics.org/cig/Members/tan2/scaling/document_view">http://www.geodynamics.org/cig/Members/tan2/scaling/document_view</a><br><br><br>Cheers,<br>Eh Tan<br><br>_______________________________________________<br>CIG-MC mailing list<br>CIG-MC@geodynamics.org<br>http://geodynamics.org/cgi-bin/mailman/listinfo/cig-mc<br></div></blockquote></div><br><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>-----------------------------</div><div>Associate Professor, U.C. Davis</div><div>Department of Geology/KeckCAVEs</div><div>Earth & Physical Sciences Bldg, rm 2129</div><div>Davis, CA 95616</div><div>-----------------</div><div><a href="mailto:mibillen@ucdavis.edu">mibillen@ucdavis.edu</a></div><div>(530) 754-5696</div><div><b>--------------------------</b></div><div><b>** Note new e-mail, building, office</b></div><div><b> information as of Sept. 2009 **</b></div><div>-----------------------------</div></div></div></span></div></span></div></span> </div><br></div></body></html>