<div class="gmail_quote">On Sat, Jan 21, 2012 at 10:50, Dominik Szczerba <span dir="ltr"><<a href="mailto:dominik@itis.ethz.ch">dominik@itis.ethz.ch</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div id=":10c">Jed, Barry: thanks for the responses. I was aware of the related FAQ<br>
entry but somehow thought only standard desktop SMPs were concerned. I<br>
never suspected interconnect communication to be better than internal<br>
memory bus...</div></blockquote></div><br><div>You are conflating memory bandwidth with network bandwidth. You need memory bandwidth if you have a working set larger than cache, but each socket only has enough memory bandwidth for one or two cores, so adding more cores doesn't speed up your program. Network performance is a separate issue.</div>