[PD] [bob~] denormals issue?

[katja]

Hi Christof,

Makefile.pdlibbuilder passes flags '-march=pentium4 -msse -msse2
-mfpmath=sse' for optimization to the compiler on Windows. You could
try compiling without (some of) these flags to see if they are
responsible for the different behavior. Makefile-defined optimization
flags can be overriden with argument CFLAGS given on command line.

The effect of optimization flags on denormals varies per processor
type, unfortunately. When we had denormals on Raspberry Pi ARMv6 they
wouldn't go away no matter what flags, is what I remember. Even if
your test reveals a beneficial effect from compiler flags, it is
better when denormals are detected and flushed in the C code. Anyway,
it is still interesting to know what makes the difference.

Katja

On Wed, Sep 21, 2016 at 12:32 AM, Christof Ressi <christof.ressi at gmx.at> wrote:
> Hmmm... I compiled [bob~] myself with MinGW and pd-lib-builder and I noticed two things:
> 1) the CPU rise is gone
> 2) it needs only half the CPU. I put 20 [bob~] objects in a switched subpatch and measured the CPU load. The DLL which comes with the Windows binaries needs 15%, while my own DLL needs only 7%! That's quite a deal...
>
> Christof
>
> PS: I attached the DLL in case you wanna try it yourself.
>
>
>> Gesendet: Samstag, 17. September 2016 um 22:58 Uhr
>> Von: "Christof Ressi" <christof.ressi at gmx.at>
>> An: pd-list at iem.at, "Miller Puckette" <msp at ucsd.edu>
>> Betreff: [PD] [bob~] denormals issue?
>>
>> Hi Miller,
>>
>> feeding audio into [bob~] and then going to zero will increase the CPU load by ca. 6%. Clearing the filter or adding a tiny amount of noise brings the CPU load back to its usual level immediately, so I guess it's a problem with denormals.
>> My Pd load meter won't really show the increase, but it's clearly visibly on Process Explorer.
>>
>> See my attached patch. Tried with Pd 0.47.1, Lenovo Thinkpad L440, Windows 7.
>>
>> Christof_______________________________________________
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