Re: Anonymous code/data/create-does

From	mhx@iae.nl (Marcel Hendrix)
Subject	Re: Anonymous code/data/create-does
Newsgroups	comp.lang.forth
Message-ID	<76990196998434@frunobulax.edu> (permalink)
Date	2013-04-07 02:04 +0200
References	<f36cb9e7-c462-42de-b290-a5382040186d@r6g2000yqh.googlegroups.com>
Organization	Wanadoo

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Alex McDonald <blog@rivadpm.com> writes Re: Anonymous code/data/create-does

> On Apr 6, 11:40 am, m...@iae.nl (Marcel Hendrix) wrote:
>> Here is small application using the ANONS package from my previous posting.
[..]
>> On Windows the threaded version is many times slower than the serial one, on
>> Linux it makes no difference. This is probably because the four threads need
>> to access the same memory locations quite frequently. It is a pity, the syntax
>> with the anons is quite nice.
[..]

> Are you writing in different threads to areas < n bytes apart, where n
> is the cacheline size, for the Window's versions?

Definitely (see above). The pde1 algorithm is such that this can't be avoided.
The matrix rows on the border of the 4 regions must be accessed by two threads.

All my experience says that once threads write in the same area the 
performance goes seriously down the drain.

>                                                   Or dirtying a large
> number of cachelines in quick sequence? I've noticed very dramatic
> slowdowns for my own code where that's the case. I'm surprised you
> don't see it on Linux; but perhaps the threads are being serially
> scheduled...

We are talking about a 64 x 64 float array and maybe 4 .. 8K of code.
Would that not fit in the caches?

> You don't mention the processor.

i7 920 @2.66 GHz on Windows, on Linux it is i7 920 @3.3GHz.
Were there bugfixes for the i7 that would affect threading?

-marcel

PS: Don't post using quoted-printable.

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Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-02 23:46 +0200
  Re: Anonymous code/data/create-does "WJ" <w_a_x_man@yahoo.com> - 2013-04-02 22:51 +0000
  Re: Anonymous code/data/create-does "WJ" <w_a_x_man@yahoo.com> - 2013-04-02 23:00 +0000
  Re: Anonymous code/data/create-does Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-04-03 11:07 +0100
    Re: Anonymous code/data/create-does m.a.m.hendrix@tue.nl - 2013-04-03 06:53 -0700
      Re: Anonymous code/data/create-does Alex McDonald <blog@rivadpm.com> - 2013-04-03 13:43 -0700
        Re: Anonymous code/data/create-does Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-04-04 18:07 +0100
    Re: Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-04 00:38 +0200
      Re: Anonymous code/data/create-does Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-04-04 18:18 +0100
        Re: Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-04 20:29 +0200
          Re: Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-06 20:40 +0200
            Re: Anonymous code/data/create-does Alex McDonald <blog@rivadpm.com> - 2013-04-06 14:09 -0700
              Re: Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-07 02:04 +0200
                Re: Anonymous code/data/create-does Alex McDonald <blog@rivadpm.com> - 2013-04-06 20:34 -0700
                Re: Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-07 14:00 +0200
                Re: Anonymous code/data/create-does kenney@cix.compulink.co.uk - 2013-04-08 02:38 -0500
                Re: Anonymous code/data/create-does Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-04-08 10:58 +0200
                Re: Anonymous code/data/create-does Alex McDonald <blog@rivadpm.com> - 2013-04-08 14:57 -0700
                Re: Anonymous code/data/create-does Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-08 19:26 +0200
                Re: Anonymous code/data/create-does kenney@cix.compulink.co.uk - 2013-04-09 02:07 -0500
  Re: Anonymous code/data/create-does mhx@iae.nl (Marcel Hendrix) - 2013-04-03 22:44 +0200
    Re: Anonymous code/data/create-does Lars Brinkhoff <lars.spam@nocrew.org> - 2013-04-04 12:42 +0200
      Re: Anonymous code/data/create-does Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-04 07:04 -0500
        Re: Anonymous code/data/create-does Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-04 07:07 -0500

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