Re: matrix multiplication

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: matrix multiplication
Date	2017-05-19 17:26 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2017May19.192659@mips.complang.tuwien.ac.at> (permalink)
References	<de96ca50-66d1-4518-a2a5-103dac0bebfb@googlegroups.com> <39defc56-99d0-42d7-8242-c16df26ca409@googlegroups.com> <2017May19.171325@mips.complang.tuwien.ac.at>

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anton@mips.complang.tuwien.ac.at (Anton Ertl) writes:
>Results for a 500x500 matrix multiply on a Core i5-6600K:
>
>Forth-94 Forth-2012 Forth-2012 Forth-94 Forth-94 
>Myneni  Myneni/Ertl     Ertl   Rees/Ertl   pahihu 
>109966M     107831M    1046M       1202M    1517M vfxlin Ndp387.fth
>  2986M       2260M    2220M       2945M    2764M gforth-fast
>  4028M       4076M    4844M       5067M    5017M SwiftForth HW stack, no WAIT
>
>I don't know what in this code slows down VFX so much.  It does not
>appear to be the classical code-close-to-written-data problem (the
>inner loop does not write data close to the code, and the number of
>icache misses (2.8M) is not high enough to explain such a big number
>of cycles).  The code generated by VFX (see below) for the inner loop
>looks inconspicuous to me.

I looked at it with "perf record -e cycles" and "perf report", and got
the following for the inner loop:

       ( 080C6E60    FF7500 )       PUSH      [EBP]
 0.26% ( 080C6E63    53 )           PUSH      EBX
       ( 080C6E64    53 )           PUSH      EBX
       ( 080C6E65    8B5D00 )       MOV       EBX, [EBP]
       ( 080C6E68    DB2B )         FLD       TBYTE 0 [EBX]
 0.85% ( 080C6E6A    5B )           POP       EBX
       ( 080C6E6B    DB2B )         FLD       TBYTE 0 [EBX]
 1.75% ( 080C6E6D    DEC9 )         FMULP     ST(1), ST
52.46% ( 080C6E6F    DEC1 )         FADDP     ST(1), ST
42.25% ( 080C6E71    5B )           POP       EBX
 1.11% ( 080C6E72    5A )           POP       EDX
       ( 080C6E73    031D70340A08 ) ADD       EBX, [080A3470]
 0.23% ( 080C6E79    53 )           PUSH      EBX
 0.23% ( 080C6E7A    83C208 )       ADD       EDX, 08
       ( 080C6E7D    5B )           POP       EBX
 0.32% ( 080C6E7E    83042401 )     ADD       [ESP], 01
 0.12% ( 080C6E82    8344240401 )   ADD       [ESP+04], 01
 0.20% ( 080C6E87    895500 )       MOV       [EBP], EDX
       ( 080C6E8A    71D4 )         JNO       080C6E60

Everything else had 0.08% or fewer cycles.  The locations associated
with the events are not very precise, but in this case they point to
the FADDP.  It's still unclear to me what the problem is.  One thing
that one might suspect is denormal numbers, but they cannot occur with
this input (only integers converted to floats).

- 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 2017: http://www.euroforth.org/ef17/

Thread

matrix multiplication krishna.myneni@ccreweb.org - 2017-05-17 15:13 -0700
  Re: matrix multiplication stephen@mpeforth.com (Stephen Pelc) - 2017-05-17 22:31 +0000
    Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-17 15:39 -0700
      Re: matrix multiplication rickman <gnuarm@gmail.com> - 2017-05-18 03:22 -0400
        Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-18 00:29 -0700
          Re: matrix multiplication rickman <gnuarm@gmail.com> - 2017-05-18 03:48 -0400
          Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-18 08:42 +0000
  Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-18 00:25 -0700
    Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-19 15:13 +0000
      Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-19 17:26 +0000
        Re: matrix multiplication Alex <alex@rivadpm.com> - 2017-05-19 18:56 +0100
        Re: matrix multiplication Paul Rubin <no.email@nospam.invalid> - 2017-05-19 21:48 -0700
        Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-20 10:21 +0000
          Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-20 06:12 -0700
          Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-20 09:47 -0700
            Re: matrix multiplication Paul Rubin <no.email@nospam.invalid> - 2017-05-20 15:31 -0700
              Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-21 04:46 -0700
                Re: matrix multiplication mhx@iae.nl - 2017-05-21 13:41 -0700
                Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-21 15:32 -0700
            Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-21 07:19 +0000
              Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-21 05:10 -0700
                Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-21 14:29 +0000
                Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-21 09:17 -0700
      Re: matrix multiplication stephen@mpeforth.com (Stephen Pelc) - 2017-05-19 20:54 +0000
      Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-19 14:33 -0700
        Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-19 16:12 -0700
        Re: matrix multiplication anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-20 14:48 +0000
    Re: matrix multiplication krishna.myneni@ccreweb.org - 2017-05-19 18:38 -0700

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