On Mon, 5 Sep 2005 20:35:10 -0700 Mark Knecht <[EMAIL PROTECTED]> wrote:
> Bob, > I don't think this was ever the point. The question was: "For this > specific machine what would be the best flags?" > You;ll hate this - it depends on what your main apps do. Are they i/o intensive, compute intensive - more integer, specific FP instruction set? Small enough to fit into L2 cache, do lots of branching, multithreaded? > I have a specific revision of the AMD64 process. What flags should > I use? Possibly some sort of test could compile lots of things, look > at numbers, and allow me to make a quantitive decision instead of just > shooting in the dark. > If you don't have a contained set of apps that represent a set of conditions that can be specifically defined, no benchmark is going to give a correct answer. In other words - your running a general purpose desktop, then there is no specific set of flags that will optimize everything. There is a set of AMD optimized strings that is being put into glibc. But it won't be for awhile - it does significant breakage to nano. And maybe to other apps. No specific compiler flags will be required for this optimization to happen - it will double memcopy speed. And that alone will provide a significant increase in performance with just a recompile - more performance than is obtainable by a set of flags. Finally, what is done by the people dropping US$100K to US$1M, they take the app they are going to run an test with that. They don't rely on benchmarks. Figure out what it is that will be your primary app. Find out how to get performance measurements on it - run sar if you have to. Change the compiler flags and re-run. Look for the bottlenecks and work to eliminate them. See - [ N] app-admin/sysstat (5.0.5-r2): System performance tools for Linux Bob - -- [email protected] mailing list
