Excuse my ignorance: not sure how to start the below version of pd on the rpi?
I have the full path but then what?
if I do (in command line) pd /place/where/new/pd/is/bin/pd It signals watchdog.
I also still have regular pd 0.44.0 installed btw.
Sorry if this is dumb dumb dumb dumb Duuummmbbb.
Jb
On 24 January 2013 09:14, katja katjavetter@gmail.com wrote:
'Undenormalized' Pd build for Raspberry Pi is temporarily parked here for testing purposes (will be removed when Miller's release is fixed in this sense):
www.katjaas.nl/temp/pd-0.44-0-normalized.tar.gz
This is a locally installed Pd, like Miller's distribution. You can start it from command line with the full path to pd-0.44-0-normalized/bin/pd. It's not a .deb, so it can't be installed under supervision of package manager.
Katja
On Wed, Jan 23, 2013 at 9:15 PM, Julian Brooks jbeezez@gmail.com wrote:
Hey Katja,
Would you mind sharing the 'normalised' Pd-0.44.0 for RPi please.
Cheers,
Julian
On 23 January 2013 18:23, katja katjavetter@gmail.com wrote:
Now I recompiled the Pd-0.44.0 release on Raspberry Pi (took me a few hours, not only because Pi is so slow) with PD_BIGORSMALL enabled for arm in m_pd.h. Using bigorsmalltest.pd from my previous mail I verified that the macro is implemented indeed.
Martin Brinkmann's patch chaosmonster1 (http://www.martin-brinkmann.de) gives a beautiful illustration of the improvement. This patch is full of filters and delay lines. At it's initial settings, there is no subnormals problem. But if you set the bottom slider to the right, it gets silent. With Pd-0.44-0 release, CPU load explodes. With the 'normalized' Pd, nothing special happens.
And indeed, the PD_BIGORSMALL conditional checks come for free: with initial settings of the chaosmonster1, performance is equivalent in both Pd's. Cool! Hopefully this is similar on armv7.
Katja
On Wed, Jan 23, 2013 at 5:01 PM, Hans-Christoph Steiner hans@at.or.at wrote:
hey Katya,
This also sounds like good evidence for your idea of writing C code
that
modern compilers optimize well. Using unions for aliasing allows the compiler to do all the new tricks, then writing loops that auto-vectorize gives us the real benefits. Also, I think we can see some gains by using memcpy() since on modern libc version, those are highly optimized for the given CPU, dynamically choosing the routines based on what instructions are available. memcpy will use things like SSSE2 if its available.
.hc
On 01/23/2013 07:47 AM, katja wrote:
Finally some good news on this topic. Earlier I stated that 'big or small tests' are expensive for the Pi, but that is not by definition the case. There must have been other conditions blurring my impression. I've now done a systematic test where other influences
are
ruled out. A test class [lopass~] with exactly the same routine as [lop~] was made, but compiled with PD_BIGORSMALL() macro enabled. It was verified that [lopass~] is not affected by denormals. Performance comparison of [lop~] and [lopass~] shows that both objects cause equivalent CPU load. Meaning, Raspberry Pi gives the 'big or small checks' for free! At least in the case of this simple filter. Please try attached bigorsmalltest.zip on the Pi to see if I'm not dreaming.
While I was at the topic anyway, I also tried a big or small test
with
union instead of direct type aliasing. It has the advantage that the compiler can apply strict aliasing rules. This test with unions did not cause extra CPU load either on the Pi. If you want to verify this result, enable the call to bigorsmall() instead of PD_BIGORSMALL in lopass~.c and recompile.
The fact that these tests do not cause extra CPU load, indicate that they are done in parallel with other instructions. Float and int registers are apparently strictly separated on armv6, there's no such thing like Intel's xmm registers or armv7's NEON. As it happens, the big or small tests are done on ints, aliases of the floats that must be tested. Initially I assumed that the transport of floats from vfp to the arm integer processor would be expensive, but if the instructions are done simultaneously it may be an advantage instead. Another thing is that ARM implements branch predication instead of branch prediction. Those terms look almost the same but the routines are very different. Predication is when instructions for both
branches
are executed, and the wrong result is simply discarded later.
Conclusions from the limited test with [lop~] and [lopass~] do not mean that all sorts of conditional checks are cheap on the Pi, or on ARM in general. If PD_BIGORSMALL is enabled for RPi using
compile-time
definition __arm__, it will also hold for armv7, but it may have very different result there. At the moment I have no access yet to an
armv7
device. Maybe someone can recompile test class [lopass~] and do the tests on Beagleboard or Cubieboard? Otherwise I may be able to do it on my friend's PengPod when that has arrived.
Katja
On Tue, Jan 22, 2013 at 8:54 PM, Miller Puckette msp@ucsd.edu
wrote:
thanks - I'd better try this and find out what's going on :)
M
On Mon, Jan 21, 2013 at 11:54:29AM +0100, katja wrote: > Tried the 0.44.0 build from your website. It has the same issue
with
> subnormal values. My test patch is with [lop~]. If inf or nan is
fed
> into [lop~], these 'values' keep circulating in the object, it can
no
> longer process normal signal values. > > I also tried my reverb stuff with specific compiler options for
Pi's
> processor: > > -march=armv6zk > -mcpu=arm1176jzf-s > -mtune=arm1176jzf-s > > With these options, gcc should be able to decide that RunFast mode
is
> permitted. But even in combination with -ffast-math (which in turn > sets -funsafe-math-optimizations and -fno-trapping-math amongst > others), denormals are still there. I'm literally out of options
for
> the moment. Sorry for not having better news. > > Katja > >
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