[PD] ICC compile [or: PD + P4 + Linux = massive headache!]
TimBlechmann at gmx.net
Mon May 10 12:43:25 CEST 2004
> What are the maintainers of the windoze packages of PD using to
> compile? Whatever it is, it seems to clear up any denormal or CPU
> spike problems.
just a guess, but maybe the linux system libraries create more denormals
than the windows ones ...
> > well, there is pd's PD_BADFLOAT macro that _should_ to that, too,
> > but this has only effect if the nubers are already denormal, so
> > maybe it's a good idea to reset the value to flush every number a 24
> > / 32 bit dac would consider to be zero to zero...
> Can you tell me a bit more about this? How and where should I start
> with that?
the PD_BADFLOAT macro is currently just checking for actual denormals...
denormals occur at about 1e-34 ... a 32 bit dac should have a resolution
of about 5e-10 ... so i suppose we could implement a macro that flushes
everything below 1e-12 to zero... the best would be to find a fancy
mask, to detect these numbers ... well, you'll have to mess around with
mantissa ... if you could have a look at this it would be great...
> I have found that certain objects have *stong* denormal tendencies,
> including hip~, lp~, np~, throw~, catch~ and probably more that I
> haven't weeded out yet.
well, digital filters and other delay lines are dangerous about
denormals, but i'm a bit confused about the throw~ / catch~ objects ...
i haven't had a look at the code, but to me it seems they just copy
sample arrays ...
> The bottom line is that patches which are completely fine to run on
> windoze and on most AMD processors with Linux completely screw up my
> P4 laptop. We are talking grinding halts of DSP, sudden [+ lasting!]
> leaps of CPU usage over 100% and even completely freezing the machine
> if I happen to be in realtime mode. Not pretty.
i know the problem, tooo :-(
> Using "./configure --enable-icc --enable-optimize=pentium4
> --enable-jack --enable-fftw" still uses GCC. Using "CC=icc CXX=icc"
> tells it to use ICC, but I get an error that the C compiler cannot
> create executables. I have a hunch that this is because I still
> haven't gotten this ridiculous key ["It should arrive within one
> business day", sez Intel...]
you shouldn't have to set the CC or CXX variables ... i'll have a look
at it ... about the configure message ... is you icc executable in the
/usr/bin path? if not, you'll probably have to create a symlink to it...
Tim mailto:TimBlechmann at gmx.de
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