[OLPC-AU] Csound slow on XO 1.75

Barry Vercoe bv at media.mit.edu
Sat Jul 7 21:08:21 EDT 2012


Thorin

C Compiler optimization at the time of compiling Public Csound on the 
ARM is a possible cause.
More likely -- since Csound is highly Floating-Point intensive -- is 
whether the compiler is using the ARM Hardware Floating-Point Processor, 
or FPP Emulation.
If only the latter for now, then simply use the INTEGER AUDIO DATA PATHS 
switch in the Orchestra files, which will keep all audio-rate signal 
processing in fixed-point integers, and will be much faster than 
simulated floating point.

This option exists in CsoundXO.  Simply include "INTAUDIO" near the top 
of your orchestra, before the 1st INSTR statement.
The INTAUDIO switch does not exist in Public Csound, which is probably 
what you are using.

-- barry


On 7/7/2012 2:54 PM, Sridhar Dhanapalan wrote:
> CCing Barry, who may be able to shed some light on this.
>
> Sridhar
>
>
> On 6 July 2012 16:44, thorin kerr <thorin.kerr at gmail.com> wrote:
>> I've been having some trouble with Csound on the XO 1.75. A quick benchmark
>> test suggests performance of Csound on the 1.75 is substantially slower.
>> Attached are two logs of an identical test conducted on an XO 1.5 and an XO
>> 1.75.
>>
>> of note,
>> XO 1.5:
>> Elapsed time at end of performance: real: 38.003s, CPU: 37.290s
>>
>> XO 1.75
>> Elapsed time at end of performance: real: 149.952s, CPU: 141.670s
>>
>> If I were to speculate, without having looked further, my guess is csound
>> compilation isn't being optimised for ARM. It's causing realtime performance
>> problems in jam2jam, but I must admit I don't relish the task of compiling
>> csound myself.
>>
>>
>> Thorin
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> OLPC-AU mailing list
>> OLPC-AU at lists.laptop.org
>> http://lists.laptop.org/listinfo/olpc-au
>>
>


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