On 6/21/07, <b class="gmail_sendername">Kendall Bailey</b> <<a href="mailto:krbailey@gmail.com">krbailey@gmail.com</a>> wrote:<div><span class="gmail_quote"></span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
I have a math optimization app that runs for several minutes on a dual<br>proc/dual core opteron SLES 9 box. Plenty of RAM. It uses 4 threads<br>to do some parallel computation to take advantage of all 4 cpu cores.<br>Looking at 'top', or using 'time' to measure cpu time, it's logging
<br>30% or more sys time vs. 60-70% user time during the parallel phases.<br>I ran it with 'strace -c' and that says only 0.003 seconds are spent<br>in system calls. No system calls going on at all on the 4 threads.
<br>So what does the 'sys' time represent as reported by top?<br><br>Thanks.<br>Kendall<br>_______________________________________________<br>Cialug mailing list<br><a href="mailto:Cialug@cialug.org">Cialug@cialug.org
</a><br><a href="http://cialug.org/mailman/listinfo/cialug">http://cialug.org/mailman/listinfo/cialug</a><br></blockquote></div><br>I'm not very knowledgable in this area, but perhaps some of the libraries you are using have to make syscall's to complete. Perhaps something to do with the threading.
<br><br>Like I said, it's just a guess.<br clear="all"><br>-- <br>Jerry H<br>jweida [-at-] gmail [-dot-] com