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Re: revisiting a prgramming problem

From mhx@iae.nl (Marcel Hendrix)
Subject Re: revisiting a prgramming problem
Newsgroups comp.lang.forth
Message-ID <93188810938433@frunobulax.edu> (permalink)
Date 2014-10-25 15:17 +0200
References <544a2a5e$0$6868$e4fe514c@dreader36.news.xs4all.nl>
Organization SunSITE.dk - Supporting Open source

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mhx@iae.nl (Marcel Hendrix) wrote Re: revisiting a prgramming problem

> albert@spenarnc.xs4all.nl (Albert van der Horst) writes Re: revisiting a prgramming problem
[..]
> The basic assumption up to now has been that conditional jumps are 
> bad for the run-time. I didn't test that here, and it might very well be
> wrong. Anyway, I suspect the difference will be so small that it only 
> matters for those that are using optimizing compilers (and then in only 
> extreme cases).

Testing tells me it is a real effect, and a biggie for our snippet.

ANEW -sumsq

: SQR ( u -- u^2 ) DUP * ;

: suosq ( z y x -- a )
  2dup 
  MAX SQR -rot ( -- z u^2 y x )
  MIN rot  
  MAX SQR + ;

: 2SORT 2DUP < IF SWAP THEN ;
: 2MAX 2SORT ROT 2SORT DROP ;
: SQSUM 2MAX DUP * SWAP DUP * + ;

#1000000000 VALUE #times
: BENCH ( -- )
	1 2 3 LOCALS| z y x |
	CR ." suosq random : "  TIMER-RESET #times 0 DO  RANDOM TO x RANDOM TO y RANDOM TO z  x y z suosq drop  LOOP .ELAPSED
	CR ." suosq fixed  : "  TIMER-RESET #times 0 DO  RANDOM drop RANDOM drop RANDOM drop  x y z suosq drop  LOOP .ELAPSED
	CR ." sqsum random : "  TIMER-RESET #times 0 DO  RANDOM TO x RANDOM TO y RANDOM TO z  x y z sqsum drop  LOOP .ELAPSED 
	CR ." sqsum fixed  : "  TIMER-RESET #times 0 DO  RANDOM drop RANDOM drop RANDOM drop  x y z sqsum drop  LOOP .ELAPSED ;

FORTH> bench cr bench cr bench
suosq random : 10.135 seconds elapsed.
suosq fixed  : 7.043 seconds elapsed.
sqsum random : 13.461 seconds elapsed.
sqsum fixed  : 7.031 seconds elapsed.

suosq random : 7.498 seconds elapsed.
suosq fixed  : 7.043 seconds elapsed.
sqsum random : 13.464 seconds elapsed.
sqsum fixed  : 7.026 seconds elapsed.

suosq random : 7.501 seconds elapsed.
suosq fixed  : 7.040 seconds elapsed.
sqsum random : 13.469 seconds elapsed.
sqsum fixed  : 7.085 seconds elapsed. ok

After the cache warms up, the branchless code (suosq) runs at ~7 seconds, 
independent from it being fed unpredictable or predictable data. The 
branching code (sqsum) is about twice slower with random data and the 
same speed as suosq for predictable data.

-marcel

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revisiting a prgramming problem gavino_himself <visploveslisp@gmail.com> - 2014-10-14 15:55 -0700
  Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-14 18:52 -0700
    Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 17:58 +0200
      Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-21 09:09 -0700
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 22:18 +0200
          Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-10-23 15:44 -0400
            Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-23 17:01 -0400
            Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 21:33 -0800
              Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-11-29 20:40 -0500
                Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-01 22:43 -0800
                Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-12-02 02:47 -0500
                Re: revisiting a prgramming problem Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2014-12-02 11:53 +0000
                Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-02 05:23 -0800
                Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-12-02 09:01 -0500
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 22:25 +0200
          Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-21 16:10 -0700
            Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 21:41 -0800
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 22:30 +0200
          Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-01 22:45 -0800
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 23:04 +0200
      Re: revisiting a prgramming problem Mark Wills <markwills1970@gmail.com> - 2014-10-21 10:17 -0700
        Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-22 02:13 -0400
          Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-21 23:26 -0700
            Re: revisiting a prgramming problem "Alex McDonald" <blog@rivadpm.com> - 2014-10-22 16:18 +0100
              Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-22 21:27 +0200
                Re: revisiting a prgramming problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-24 10:30 +0000
                Optimal comparisons for m maximums from n items  (was Re: revisiting a prgramming problem) "Alex McDonald" <blog@rivadpm.com> - 2014-10-24 16:29 +0100
                Re: Optimal comparisons for m maximums from n items  (was Re: revisiting a prgramming problem) albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-25 08:27 +0000
                Re: Optimal comparisons for m maximums from n items (was Re: revisiting a prgramming problem) "Alex McDonald" <blog@rivadpm.com> - 2014-10-25 18:54 +0100
                Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-25 13:28 +0200
                Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-25 14:28 +0200
                Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-25 15:17 +0200
            Re: revisiting a prgramming problem Gerry Jackson <spam@qlikz.org> - 2014-10-22 21:57 +0100
              Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-22 14:06 -0700
                Re: revisiting a prgramming problem Bernd Paysan <bernd.paysan@gmx.de> - 2014-10-23 00:03 +0200
                Re: revisiting a prgramming problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-23 14:46 +0000
                Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-23 08:16 -0700
                Re: revisiting a prgramming problem "Alex McDonald" <blog@rivadpm.com> - 2014-10-23 19:21 +0100
                Re: revisiting a prgramming problem "Alex McDonald" <blog@rivadpm.com> - 2014-10-23 20:02 +0100
                Re: revisiting a prgramming problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-23 20:29 +0000
                Re: revisiting a prgramming problem Coos Haak <chforth@hccnet.nl> - 2014-10-23 22:23 +0200
              Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-23 00:36 +0200
                Re: revisiting a prgramming problem Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-10-24 10:44 +0100
              Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-22 17:26 -0700
                Re: revisiting a prgramming problem Michael Barry <barrym95838@yahoo.com> - 2014-10-23 00:02 -0700
          Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 23:10 -0800
        Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 21:42 -0800
  Re: revisiting a prgramming problem Roger Levy <roger.levy@gmail.com> - 2014-10-15 08:18 -0700
    Re: revisiting a prgramming problem Roger Levy <roger.levy@gmail.com> - 2014-10-15 08:18 -0700
      Re: revisiting a prgramming problem november.nihal@gmail.com - 2014-10-15 08:57 -0700
      Re: revisiting a prgramming problem Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-10-15 17:10 +0100
      Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-17 21:53 -0400
    Re: revisiting a prgramming problem Roger Levy <roger.levy@gmail.com> - 2014-10-15 08:19 -0700
  Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-22 00:30 +0200
    Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-21 16:07 -0700
      Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-22 03:23 +0200
        Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-22 02:15 -0400
          Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-22 12:52 +0200
        Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-22 17:19 -0700
          Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-23 16:10 +0200
      Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-22 02:14 -0400
      Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 23:21 -0800
      Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-12-06 02:34 +0000
      Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-12-27 08:00 +0000
        Re: revisiting a prgramming problem Mark Wills <markwills1970@gmail.com> - 2014-12-27 05:15 -0800
  Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-11-29 17:20 +0000
    Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-29 12:00 -0800
    Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-12-02 16:15 +0000
  Re: revisiting a prgramming problem Paul Sephton <prsephton@gmail.com> - 2014-12-02 05:06 -0800
    Re: revisiting a prgramming problem Paul Sephton <prsephton@gmail.com> - 2014-12-02 05:14 -0800
    Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-02 05:24 -0800

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