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Re: Forth dictionary implementation and performance

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anton@mips.complang.tuwien.ac.at (Anton Ertl) writes:
>It takes 180M cycles with gforth-fast on the reference machine, 36M of
>which are consumed when just starting gforth-fast (so essentially 144M
>for the actual program).  Here are the detailed results:
>
>      179883538  cycles                   #      0.000 M/sec
>      157894542  instructions             #      0.878 IPC  
>        3568630  branch-misses            #      0.000 M/sec
>        1269773  L1-dcache-load-misses    #      0.000 M/sec
>       53807814  L1-dcache-loads          #      0.000 M/sec
>
>How much of that is due to FIND-NAME?  If I first define FIND-NAME as
>
>: find-name 2drop 0 ;
>
>I get
>
>
>      149942202  cycles                   #      0.000 M/sec
>      139562133  instructions             #      0.931 IPC  
>        2626759  branch-misses            #      0.000 M/sec
>         839842  L1-dcache-load-misses    #      0.000 M/sec
>       47026545  L1-dcache-loads          #      0.000 M/sec
>
>If I replace it with 
>
>: find-name 2drop [ s" #wordlists" find-name ]l ;
>
>I get
>
>      154854243  cycles                   #      0.000 M/sec
>      143084355  instructions             #      0.924 IPC  
>        2775349  branch-misses            #      0.000 M/sec
>         884432  L1-dcache-load-misses    #      0.000 M/sec
>       48098345  L1-dcache-loads          #      0.000 M/sec
>
>I.e., 25-30M cycles spent in FIND-NAME.  So there is quite a bit of
>potential for improvement there, but given that the other overheads
>are so large, it's probably better to spend the effort elsewhere
>first.

Ok, looking at it again, dynamic native code generation is disabled in
the engine built on that machine (I now remember that gcc-4.4 was one
of the particularly bad versions).  Running on the Haswell with
gcc-4.9.2, I see

 56837722      cycles:u                 
135146121      instructions:u            #    2.38  insns per cycle        
   266092      branch-misses:u                                             
   553092      L1-dcache-load-misses     #    1.57% of all L1-dcache hits  
 35236800      L1-dcache-loads                                         

With : find-name 2drop 0 ;

 50547534      cycles:u                 
122063613      instructions:u            #    2.41  insns per cycle        
   239118      branch-misses:u                                             
   459065      L1-dcache-load-misses     #    1.44% of all L1-dcache hits  
 31907684      L1-dcache-loads                                         

With : find-name 2drop [ s" #wordlists" find-name ]l ;

 51313405      cycles:u                 
122069990      instructions:u            #    2.38  insns per cycle        
   241427      branch-misses:u                                             
   476163      L1-dcache-load-misses     #    1.49% of all L1-dcache hits  
 31896977      L1-dcache-loads                                         

So the FIND-NAME overhead is 5-6M instructions.  Still quite a bit
more than the best the students got (and their result include all the
other things as well), but significantly better than it appeared at
first.  But again, other overheads dominate here, and probably even
more so for real text interpretation.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2015: http://www.rigwit.co.uk/EuroForth2015/

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Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-29 17:42 +0000
  Re: Forth dictionary implementation and performance Paul Rubin <no.email@nospam.invalid> - 2016-01-29 16:20 -0800
    Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-30 13:54 +0000
      Re: Forth dictionary implementation and performance Paul Rubin <no.email@nospam.invalid> - 2016-01-31 11:57 -0800
        Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-02-01 06:47 +0000
          Re: Forth dictionary implementation and performance Paul Rubin <no.email@nospam.invalid> - 2016-02-01 00:47 -0800
            Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-02-01 11:13 +0000
  Re: Forth dictionary implementation and performance Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-30 01:57 +0100
    Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-30 17:18 +0000
      Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-30 17:51 +0000
  Re: Forth dictionary implementation and performance Paul Rubin <no.email@nospam.invalid> - 2016-01-29 18:01 -0800
    Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-30 13:59 +0000
      Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-30 17:38 +0000
        Re: Forth dictionary implementation and performance Paul Rubin <no.email@nospam.invalid> - 2016-01-31 12:05 -0800
          Re: Forth dictionary implementation and performance Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-02-01 03:01 +0000
          Re: Forth dictionary implementation and performance anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-02-01 06:17 +0000
            Re: Forth dictionary implementation and performance "Elizabeth D. Rather" <erather@forth.com> - 2016-01-31 21:27 -1000
  Re: Forth dictionary implementation and performance hughaguilar96@gmail.com - 2016-01-30 15:42 -0800

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