<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br></div><div><br></div><div>Hello Matt,</div><div><br></div><br><blockquote type="cite"><div><br>That stuff is rarely worth running. Without a decent model of the<br>performance, the<br>data is no help. I am not talking about network bandwidth, but memory bandwidth.<br>For a sparse matvec that comes from a simple scalar PDE, you need incredible<br>amounts of bandwidth to drive the tiny amount of flops. The equation<br>is in the paper.<br><br><blockquote type="cite">Please see the paper<br></blockquote><blockquote type="cite"> by Kaushik and Gropp which models sparse matvec performance (on<br></blockquote><blockquote type="cite">Dinesh's website).<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Which Paper on which website. Please send a link.<br></blockquote><br>I believe you want 11 and 17 here <a href="http://www.mcs.anl.gov/~kaushik/">http://www.mcs.anl.gov/~kaushik/</a><br>under the Publications link.</div></blockquote><div><br></div><div>Got it. I will look at it and check the memory bandwidth</div><br><blockquote type="cite"><div><br><br><blockquote type="cite">3) You would see better performance using a block method. Sparse matvec<br></blockquote><blockquote type="cite">without<br></blockquote><blockquote type="cite"> blocks will never see good percentages of peak (ditto for backsolve).<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">How do I use the block methods?<br></blockquote><blockquote type="cite">Since I rely on the "user-level" interfaces kspsolve etcpp., I don't see how<br></blockquote><blockquote type="cite">i could influence this.<br></blockquote><br>You can't unless your system has block structure. If it does, you can<br>use the BAIJ<br>matrix types.</div></blockquote><div><br></div><div>I'll try it.</div><div>Thank you for your advice that far.</div><div><br></div><div>Sincerly, </div><div>Christoph</div><div><br></div><div><br></div><div><br></div><div><blockquote type="cite"><div><br></div></blockquote></div></body></html>