On Mon, Oct 20, 2003 at 05:22:19PM -0700, David Mosberger wrote: > I wasn't very clear: fpswa stands for "floating-point software assist" > which is a trap that gets invoked when encountering a corner-case that > isn't handled in hardware (such as operations on infinity, NaN, or > denormals). The traps are handled in the kernel and do _not_ result > in an error, but such operatiosn of course to run more slowly. Alpha > behaves very similar, so like I mentioned earlier, it's unlikely to be > an issue with fftw2.
This is not an issue: dmesg doesn't show anything like this and the program would crash on the alpha if it were. > > There are a lot of numbers at fftw.org, but from a cursory look at it, > it does seem like peak performance of a 900MHz Itanium 2 is > significantly better than peak performance of an 833MHz Alpha. and I am using 500 to 667 MHz alphas :-) > > Oh, one thing I noticed: the folks at fftw.org used "ecc -O3" whereas > you used "ecc -O2". The main difference with -O3 is that it turns on > data prefetching. This can make a huge difference when dealing with > relatively large data sets. Not for me. The ratio is approx. the same with smaller data sets, which definitely fit into the L3 cache. Regards, Ionut -- *************** * Ionut Georgescu * http://www.physik.tu-cottbus.de/~george/ * Registered Linux User #244479 * * "In Windows you can do everything Microsoft wants you to do; in Unix you * can do anything the computer is able to do."
