Re: Ruby/Forth challenge for WJ

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: Ruby/Forth challenge for WJ
Date	2016-01-18 12:48 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2016Jan18.134817@mips.complang.tuwien.ac.at> (permalink)
References	<2016Jan15.172237@mips.complang.tuwien.ac.at> <78599219028399@frunobulax.edu> <3f866042-67c5-419c-b921-963493c5ecf5@googlegroups.com> <569a5c2e$0$23750$e4fe514c@news.xs4all.nl> <f5f6d3e8-3c6b-4ccd-92a8-fe1e87ca5d01@googlegroups.com>

Show all headers | View raw

m.a.m.hendrix@tue.nl writes:
>Only users of Forths with optimizing compilers will notice
>the effects uncovered in this thread. In a `standard' Forth
>threaded-code implementation loops can not be so tight that
>they can cause problems.

They can. A Haswell takes 2.3 cycles per NEXT on my threaded-code
microbenchmark <http://www.complang.tuwien.ac.at/forth/threading/>,
which is probably 2 cycles for the NEXT without payload, and 5 cycles
for the (LOOP)-like part of the microbenchmark (for a total of
9*2+1*5=23 cycles per iteration). With 2 cycles per NEXT, a 6 cycle
latency for the loop-counter recurrence can become critical (as in
"critical path").

From theory to practice:
perf stat -x " " -e cycles gforth-fast -e ": foo 1000000000 0 do loop ; foo bye"
6033467997 cycles
perf stat -x " " -e cycles vfxlin ": foo 1000000000 0 do loop ; foo bye"
6025464845 cycles
perf stat -x " " -e cycles gforth-fast --no-dynamic -e ": foo 1000000000 0 do loop ; foo bye"
6029161316 cycles

(on a Core i3-3227U (Ivy Bridge))

So, for the empty DO LOOP, using the recurrence through memory makes
vfxlin as slow as gforth-fast and gforth-fast --no-dynamic (the latter
being plain direct-threaded code).

I also noticed such effects when I microbenchmarked various locals and
DOES> implementations on Gforth for the last EuroForth paper. Many
differences had no effect on the performance of a Haswell, despite
significant differences in instruction count.

So I looked closer at the machine code that is executed, and found
that for these microbenchmarks, the critical path is often a
recurrence involving the virtual machine instruction pointer. The
microbenchmark involved a call in a loop, so the recurrence across the
whole loop pushed the IP to the return stack, loaded it back from the
return stack, loaded the start of the next loop iteration depending on
that, and performed a few IP increments in between. The one
microbenchmark that did not perform the call was a lot faster, almost
as fast as the empty loop (probably the performance was determined by
the recurrence of several IP increments (not present in the empty
loop) followed by loading the start of the next loop iteration (also
present in the empty loop).

All the other stuff the microbenchmarks did was performed by the
Haswell in parallel with this recurrence. I think that one reason why
the other stuff did not lead to longer recurrences is that these
benchmarks dropped anything computed on the data stack, so all the
data stack stuff became independent dependency chains (that can be
performed in parallel) rather than recurrences.

30 years ago, compilers ruined the Dhrystone 1.1 benchmark by noticing
that the results were not used and optimizing much of the computation
away. These days, we see similar effects from the hardware. The
computation is performed, but if the result is not used, it can
perform much more computation in parallel than you normally see in
useful applications.

- 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/

Thread

Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 07:47 -0800
  Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-12 16:25 +0000
    Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-12 10:45 -0600
    Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 08:46 -0800
      Re: Ruby/Forth challenge for WJ rickman <gnuarm@gmail.com> - 2016-01-12 11:57 -0500
        Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 09:22 -0800
          Re: Ruby/Forth challenge for WJ hughaguilar96@gmail.com - 2016-01-12 21:04 -0800
            Re: Ruby/Forth challenge for WJ Ron Aaron <rambamist@gmail.com> - 2016-01-13 07:59 +0200
      Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-12 19:42 +0000
        Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-12 12:53 -0800
    Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-13 15:45 +0000
      Re: Ruby/Forth challenge for WJ rickman <gnuarm@gmail.com> - 2016-01-13 13:44 -0500
        Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-13 11:39 -0800
          Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-14 05:01 +0100
          Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-14 12:28 +0000
  Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 09:50 -0800
  Re: Ruby/Forth challenge for WJ Pablo Hugo Reda <pabloreda@gmail.com> - 2016-01-12 11:50 -0800
  Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 12:30 -0800
  Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 12:43 -0800
    Re: Ruby/Forth challenge for WJ stephen@mpeforth.com (Stephen Pelc) - 2016-01-12 21:01 +0000
    Re: Ruby/Forth challenge for WJ peter.m.falth@gmail.com - 2016-01-12 15:00 -0800
      Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-12 16:13 -0800
        Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-12 16:22 -0800
        Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-12 16:24 -0800
          Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-12 17:46 -0800
            Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-12 18:39 -0800
              Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-13 13:05 -0800
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-14 04:33 +0100
                Re: Ruby/Forth challenge for WJ m.a.m.hendrix@tue.nl - 2016-01-14 03:27 -0800
                Re: Ruby/Forth challenge for WJ peter.m.falth@gmail.com - 2016-01-14 04:42 -0800
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-14 13:03 +0000
                Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-13 21:17 -0800
                Re: Ruby/Forth challenge for WJ hughaguilar96@gmail.com - 2016-01-13 21:44 -0800
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-14 10:57 +0000
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-14 12:20 -0800
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-14 13:57 -0800
                Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-14 14:22 -0800
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-14 16:14 -0800
                Re: Ruby/Forth challenge for WJ Melzzzzz <mel@zzzzz.com> - 2016-01-15 03:05 +0100
                Re: Ruby/Forth challenge for WJ Waldek Hebisch <hebisch@antispam.uni.wroc.pl> - 2016-01-15 00:41 +0000
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-15 16:22 +0000
                Re: Ruby/Forth challenge for WJ mhx@iae.nl (Marcel Hendrix) - 2016-01-16 11:44 +0200
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-16 04:49 -0800
                Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-16 15:05 +0000
                Re: Ruby/Forth challenge for WJ m.a.m.hendrix@tue.nl - 2016-01-18 03:26 -0800
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-18 12:48 +0000
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-19 22:26 +0100
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-20 03:05 -0800
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-20 21:00 +0100
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-20 15:57 -0800
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-21 23:02 +0100
                Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-22 01:25 +0000
                Re: Ruby/Forth challenge for WJ hughaguilar96@gmail.com - 2016-01-21 18:05 -0800
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-21 22:03 -0800
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-20 13:40 +0000
                Re: Ruby/Forth challenge for WJ m.a.m.hendrix@tue.nl - 2016-01-18 03:55 -0800
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-23 15:13 -0600
                Re: Ruby/Forth challenge for WJ mhx@iae.nl - 2016-01-24 00:55 -0800
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-25 04:48 -0600
                Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-25 12:39 +0000
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-25 08:05 -0600
                Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-25 16:40 +0000
                Re: Ruby/Forth challenge for WJ Mark Wills <markwills1970@gmail.com> - 2016-01-25 04:44 -0800
                Re: Ruby/Forth challenge for WJ stephen@mpeforth.com (Stephen Pelc) - 2016-01-25 14:01 +0000
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-25 08:08 -0600
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-25 11:56 -0600
                Re: Ruby/Forth challenge for WJ "Elizabeth D. Rather" <erather@forth.com> - 2016-01-25 11:12 -1000
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-26 03:33 -0600
                Re: Ruby/Forth challenge for WJ stephen@mpeforth.com (Stephen Pelc) - 2016-01-26 11:09 +0000
                Re: Ruby/Forth challenge for WJ stephen@mpeforth.com (Stephen Pelc) - 2016-01-26 11:06 +0000
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-26 07:45 -0600
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-26 16:46 +0000
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-26 11:16 -0600
                Object-oriented Forth (was: Ruby/Forth challenge for WJ) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-27 14:13 +0000
                Re: Object-oriented Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-27 10:33 -0600
                Re: Object-oriented Forth hughaguilar96@gmail.com - 2016-01-27 08:45 -0800
                Re: Object-oriented Forth Chris Curl <ccurl609@gmail.com> - 2016-01-27 09:14 -0800
                Re: Object-oriented Forth hughaguilar96@gmail.com - 2016-01-29 21:57 -0800
                Re: Object-oriented Forth Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-30 10:58 +0000
                Re: Object-oriented Forth Chris Curl <ccurl609@gmail.com> - 2016-01-30 09:38 -0800
                Re: Object-oriented Forth Coos Haak <chforth@hccnet.nl> - 2016-01-30 20:39 +0100
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-26 15:56 +0100
                Re: Ruby/Forth challenge for WJ stephen@mpeforth.com (Stephen Pelc) - 2016-01-26 20:46 +0000
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-25 22:27 +0100
                Re: Ruby/Forth challenge for WJ Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2016-01-28 14:20 +0100
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-28 08:06 -0600
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-28 16:14 +0100
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-28 10:32 -0600
                Re: Ruby/Forth challenge for WJ anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-01-28 17:26 +0000
                Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-28 12:13 -0600
                Re: Ruby/Forth challenge for WJ Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-01-29 11:07 +0000
                Re: Ruby/Forth challenge for WJ Bernd Paysan <bernd.paysan@gmx.de> - 2016-01-29 21:18 +0100
                Re: Ruby/Forth challenge for WJ Tessa Bonting <tessa.bonting@gmail.com> - 2016-01-16 06:24 -0800
          Re: Ruby/Forth challenge for WJ Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-13 05:21 -0500
            Re: Ruby/Forth challenge for WJ Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-13 05:36 -0500
            Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-13 10:33 -0800
              Re: Ruby/Forth challenge for WJ Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-14 01:37 -0500
  Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 13:45 -0800
  Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 13:55 -0800
    Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-12 14:34 -0800
    Re: Ruby/Forth challenge for WJ rickman <gnuarm@gmail.com> - 2016-01-12 19:00 -0500
      Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 16:49 -0800
        Re: Ruby/Forth challenge for WJ rickman <gnuarm@gmail.com> - 2016-01-12 22:18 -0500
  Re: Ruby/Forth challenge for WJ hughaguilar96@gmail.com - 2016-01-12 14:31 -0800
    Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-12 16:05 -0800
  Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-01-13 07:58 +0000
    Re: Ruby/Forth challenge for WJ Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-13 05:17 -0500
      Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-13 12:36 -0800
        Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-13 12:53 -0800
        Re: Ruby/Forth challenge for WJ Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-01-14 06:50 -0600
    Re: Ruby/Forth challenge for WJ Julian Fondren <julian.fondren@gmail.com> - 2016-01-13 05:36 -0800
    Re: Ruby/Forth challenge for WJ lehs <skydda.barnen@gmail.com> - 2016-01-13 11:59 -0800
    Re: Ruby/Forth challenge for WJ Chris Curl <ccurl609@gmail.com> - 2016-01-21 21:08 -0800
    Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-02-09 13:36 +0000
    Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-02-09 13:48 +0000
      Re: Ruby/Forth challenge for WJ hughaguilar96@gmail.com - 2016-02-09 12:02 -0800
    Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-02-09 13:58 +0000
    Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-02-09 14:30 +0000
    Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-02-14 15:35 +0000
      Re: Ruby/Forth challenge for WJ franck.bensusan@gmail.com - 2016-02-14 08:50 -0800
        Re: Ruby/Forth challenge for WJ Julian Fondren <julian.fondren@gmail.com> - 2016-02-14 20:09 -0800
          Re: Ruby/Forth challenge for WJ hughaguilar96@gmail.com - 2016-02-15 08:52 -0800
    Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-02-14 21:31 +0000
  Re: Ruby/Forth challenge for WJ "WJ" <w_a_x_man@yahoo.com> - 2016-01-14 22:49 +0000
    Re: Ruby/Forth challenge for WJ Paul Rubin <no.email@nospam.invalid> - 2016-01-14 15:31 -0800
      Re: Ruby/Forth challenge for WJ Melzzzzz <mel@zzzzz.com> - 2016-01-15 06:55 +0100
  Re: Ruby/Forth challenge for WJ djc <ciesinger@gmx.net> - 2016-02-11 07:39 -0800

csiph-web