<div class="gmail_quote">On Tue, May 8, 2012 at 1:32 AM, Manfred Gratt <span dir="ltr"><<a href="mailto:manfred.gratt@uibk.ac.at" target="_blank">manfred.gratt@uibk.ac.at</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
when I compile petsc with --with-debugging=0 with gcc and icc in configure there are different optimization flags set depending on compiler. So is with gcc -O set wich means -O1 optimization. While with icc -O3 optimisation is set. Is there a reason only icc gets the high performance flag while gcc not? Are there any problems when some optimizations are activated on gcc?</blockquote>
</div><br><div>I don't know why only -O1 is used with gcc, but you can pass COPTFLAGS='-O3 -march=native' or whatever you like to configure to make it use those instead.</div>