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Re: Measuring execution speed -- profiling in Forth?

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>>>>> "Albert" == Albert van der Horst <albert@spenarnc.xs4all.nl> writes:

> In article <qdm8i912ie2rkiq7vs310hq3uk0ubud3mj@4ax.com>,
> Assad  <assad.ebrahim@alum.swarthmore.edu> wrote:
[..]
>> How to measure the execution speed of an algorithm in Forth?
>> 
>> In other languages, I would use a profiler which would break out the
>> execution speed taken by various parts of the code, which is quite
>> helpful.
>> 
>> How might one do this in Forth?
>> 
>> If I were to build it myself, I would essentially fetch system time
>> (in milliseconds) and then have it accumulate the time spent within a
>> word into a variable.
>> 
>> Although I believe someone mentioned that GForth has a profiler...?

> On Pentiums practical succes can be had with the real time counter,
> allowing for nanosecond resolution.  You need a single code word in
> assembler.  This depends on the Forth. The following code from ciforth
> can help:

Here is code for Gforth on AMD64 (x86-64)-systems that reads the cycle
counter.  This should work on any 64-bit x86 linux:

abi-code tsc@  ( -- u )
   rdtsc
   .d ax  -8 di d)  mov
   .d dx  -4 di d)  mov
   -8 di d)  ax lea       \ compute new sp in result reg
   ret
end-code

You can then go on and redefine : and ; to add collect execution count
and time information for all forth routines defined in your code.  You
can see a simple profiler based on this concept is here:

 http://mosquito.dyndns.tv/opensvn/free/branches/brainless-abi/profiler.fs

A more portable version without using the x86 cycle-counter is here:

 http://sourceforge.net/p/forth-brainless/code/HEAD/tree/trunk/profiler.fs

It uses Gforth's CPUTIME word instead (less accurate and more overhead).

Of course the overhead added to all definitions is very noticeable and
collected timing data will therefore not be representative (unless you
are more careful to only enable the profiler on definitions that take
about an order of magnitude more execution time than the profiling
instrumentation code takes).

cheers,

David
-- 
GnuPG public key: http://dvdkhlng.users.sourceforge.net/dk2.gpg
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Measuring execution speed -- profiling in Forth? Assad <assad.ebrahim@alum.swarthmore.edu> - 2014-03-15 13:48 +0000
  Re: Measuring execution speed -- profiling in Forth? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-03-15 14:40 +0000
    Re: Measuring execution speed -- profiling in Forth? David Kuehling <dvdkhlng@posteo.de> - 2014-03-17 08:00 +0100
    Re: Measuring execution speed -- profiling in Forth? Assad Ebrahim <assad.ebrahim@alum.swarthmore.edu> - 2014-04-01 12:18 +0100
  Re: Measuring execution speed -- profiling in Forth? "Elizabeth D. Rather" <erather@forth.com> - 2014-03-15 11:40 -1000
  Re: Measuring execution speed -- profiling in Forth? foxaudioresearch@gmail.com - 2014-03-16 15:50 -0700
    Re: Measuring execution speed -- profiling in Forth? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-03-16 20:24 -0400
    Re: Measuring execution speed -- profiling in Forth? Bernd Paysan <bernd.paysan@gmx.de> - 2014-03-17 01:32 +0100
  Re: Measuring execution speed -- profiling in Forth? Coos Haak <chforth@hccnet.nl> - 2014-03-17 01:32 +0100
    Re: Measuring execution speed -- profiling in Forth? m.a.m.hendrix@tue.nl - 2014-03-17 01:07 -0700
  Re: Measuring execution speed -- profiling in Forth? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-03-17 03:33 -0400
    Re: Measuring execution speed -- profiling in Forth? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-03-20 20:43 +0000
      Re: Measuring execution speed -- profiling in Forth? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-03-20 18:54 -0400
  Re: Measuring execution speed -- profiling in Forth? Assad <assad.ebrahim@alum.swarthmore.edu> - 2014-03-17 08:23 +0000

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