[PlanetCCRMA] Pentium-4 and denormal numbers on planetccrma
andersvi at extern.uio.no
andersvi at extern.uio.no
Wed Jan 12 02:59:01 PST 2005
I see in the list-archives there has been issues around denormal
numbers, but it seems limitied to the ladspa tap-plugin.
Recently found that planetccrma's dist of pd & externals gave
some trouble related to "denormal numbers" on a pentium-4 based
laptop here.
Problem was it went up to 90+% cpu, and stayed there, while same
patch on athlon-based machine (half the speed) ran at 20%.
It seems that these numbers - very small numbers - are optimized
to zero automatically on some cpu's, while others, like my
P4-based here, need special handling when compiling apps.
The fix was to recompile pd and the percolate-lib with
-mcpu=pentium4 -mfpmath=sse -msse
included in CFLAGS (not sure whether "-mcpu=pentium4" actually
was necessary).
Ive started recompiling various externals and other things with
the flags included. Im not sure, but wouldnt this be a problem
with all apps running loops calculating numbers around zero
somewhere. Would it be a solution to compile coming upgrades at
planetccrma with these same flags?
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