On Thursday 14 January 2010 02:38:04 Ken Restivo wrote: > Turns out that on my Core2Duo, JACK RACK running Fons's auto-wah plugin > sucks up 6% CPU even if there is no sound going through it. > > I asked Fons about it; he can't duplicate the problem since he doesn't have > a 64-bit system. Hell, I can't even duplicate it on my 32-bit system; it's > 64-bit dependent. > > I looked at the output with Bitmeter at Fons' suggestion, and it seems > there are no denormals, inf's, or nans-- just a very small -230dB DC > offset in the code (probably to avoid denormals). > > The CPU usage ramps up before any signal is fed into the plugin. It runs > normally when there is signal, but then it keeps sucking up CPU > afterwards. I'm feeding it from fluidsynth, and bitmeter says that it > isn't sending anthing at all during silent moments. > > It doesn't run away to 99% CPU (or 50% on a Core2Duo), like it would if > there were a denormal. But still, why is it using up CPU when there's no > signal? That seems odd. And why only on my 64-bit machine? FWIW, the > 64-bit and 32-bit machines I have are even running the same kernel and > RT-patch versions (2.6.26.8-rt12). Here is a shot: Maybe the 64bit is better at calculation and -230dB are not yet good enough to avoid denormals. What if you change that code to add a bit more offset? Or use it in an ardour session for testing and try the different denormal modes of ardour to see if one helps... Have fun, Arnold
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