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Groups > comp.lang.forth > #28699

Re: Forth reinvention

From Bernd Paysan <bernd.paysan@gmx.de>
Newsgroups comp.lang.forth
Subject Re: Forth reinvention
Date 2014-02-23 02:40 +0100
Organization 1&1 Internet AG
Message-ID <lebji3$1qg$1@online.de> (permalink)
References <b5ec955a-146f-41ea-a227-22e4224cab49@googlegroups.com> <o7KdncO2m9MJxJvOnZ2dnUVZ_tOdnZ2d@supernews.com> <2014Feb21.155029@mips.complang.tuwien.ac.at> <le8an9$fi$1@online.de> <BJ-dnTMtgeYtWZXOnZ2dnUVZ_t-dnZ2d@supernews.com>

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Andrew Haley wrote:

> Bernd Paysan <bernd.paysan@gmx.de> wrote:
>> 
>> One very typical problem with these multi-core CPUs is that
>> communication overhead is quite high.  I've experimented with
>> parallelism in net2o, one task would do the Unix socket stuff, and
>> another task would do the rest of the protocol, including encryption
>> (which does cost performance, about 10 cycles per byte).  However,
>> the result was that the communication overhead between the two tasks
>> was big enough to make the parallel solution slower than the
>> do-it-all-on-one-core simple sequential solution.
> 
> Hmmm, that's a little surprising.  I'm guessing that an L3 cache hit
> in another core is maybe 75 cycles.  At 10 cycles per byte that's the
> time it takes to encrypt 7 bytes, but a cache line is 64 bytes in
> size.

And a network packet has 1024 bytes, or 10k cycles to decrypt it.  The L3 
transfer speed would be about 1 cycle per byte, and certainly worth it.

> There's some signalling overhead, but it still sounds
> worthwhile, but only just.  I suppose the problem is the latency
> signalling the worker thread to start.

Yes.  That goes through the OS, and takes ages.  There's a good reason why 
the Transputer had its links in hardware.  In any case, the OS overhead here 
is so big that the time it takes Linux to get a simple UDP packet from one 
process to another is the same amount of time it takes net2o to do the 
entire stack including encryption (as user task).  And encryption is 80% or 
90% of that.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/

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Forth reinvention dambere@web.de - 2014-02-20 01:19 -0800
  Re: Forth reinvention "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2014-02-20 05:07 -0500
    Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-20 14:56 +0000
      Re: Forth reinvention "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2014-02-20 16:16 -0500
        Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-20 23:25 +0000
          Re: Forth reinvention "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2014-02-20 20:42 -0500
            Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-21 12:41 +0000
  Re: Forth reinvention Hans Bezemer <the.beez.speaks@gmail.com> - 2014-02-20 11:18 +0100
    Re: Forth reinvention dambere@web.de - 2014-02-20 02:36 -0800
      Re: Forth reinvention Hans Bezemer <the.beez.speaks@gmail.com> - 2014-02-20 17:35 +0100
        Re: Forth reinvention dambere@web.de - 2014-02-20 11:34 -0800
          Re: Forth reinvention "Elizabeth D. Rather" <erather@forth.com> - 2014-02-20 09:53 -1000
          Re: Forth reinvention Paul Rubin <no.email@nospam.invalid> - 2014-02-20 12:23 -0800
            Re: Forth reinvention dambere@web.de - 2014-02-20 14:00 -0800
              Re: Forth reinvention Paul Rubin <no.email@nospam.invalid> - 2014-02-20 14:23 -0800
                Re: Forth reinvention dambere@web.de - 2014-02-22 02:21 -0800
                Re: Forth reinvention AKK <akk@nospam.org> - 2014-02-22 12:02 +0100
              Re: Forth reinvention Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-02-21 04:38 -0600
          Re: Forth reinvention Mark Wills <markrobertwills@yahoo.co.uk> - 2014-02-20 12:35 -0800
            Re: Forth reinvention Paul Rubin <no.email@nospam.invalid> - 2014-02-20 13:38 -0800
  Re: Forth reinvention m.a.m.hendrix@tue.nl - 2014-02-20 03:59 -0800
    Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-20 15:11 +0000
      Re: Forth reinvention m.a.m.hendrix@tue.nl - 2014-02-20 07:41 -0800
  Re: Forth reinvention Richard Owlett <rowlett@pcnetinc.com> - 2014-02-20 06:38 -0600
    Re: Forth reinvention dambere@web.de - 2014-02-20 12:03 -0800
  Re: Forth reinvention Julian Fondren <julian.fondren@gmail.com> - 2014-02-20 07:08 -0800
  Re: Forth reinvention "Elizabeth D. Rather" <erather@forth.com> - 2014-02-20 09:37 -1000
    Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-20 20:50 +0000
      Re: Forth reinvention "Elizabeth D. Rather" <erather@forth.com> - 2014-02-20 15:39 -1000
        Re: Forth reinvention albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-02-21 10:50 +0000
        Re: Forth reinvention Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2014-02-21 11:10 +0000
          Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-21 13:50 +0000
        Re: Forth reinvention Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-02-21 05:46 -0600
          Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-21 12:55 +0000
          Re: Forth reinvention anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-02-21 15:11 +0000
            Re: Forth reinvention Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-02-22 09:23 -0600
        Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-21 12:38 +0000
        Re: Forth reinvention anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-02-22 13:29 +0000
          Re: Forth reinvention "Elizabeth D. Rather" <erather@forth.com> - 2014-02-22 07:52 -1000
            Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-22 19:06 +0000
            Re: Forth reinvention anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-02-23 13:40 +0000
    Re: Forth reinvention "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2014-02-20 20:40 -0500
      Re: Forth reinvention "Elizabeth D. Rather" <erather@forth.com> - 2014-02-20 18:43 -1000
        Re: Forth reinvention Hans Bezemer <the.beez.speaks@gmail.com> - 2014-02-21 13:16 +0100
      Re: Forth reinvention stephenXXX@mpeforth.com (Stephen Pelc) - 2014-02-21 10:49 +0000
    Re: Forth reinvention anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-02-21 14:50 +0000
      Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-21 16:28 +0000
        Re: Forth reinvention anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-02-22 12:54 +0000
          Re: Forth reinvention "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2014-02-22 10:27 -0500
          Re: Forth reinvention "Alex McDonald" <blog@rivadpm.com> - 2014-02-22 17:49 +0000
      Re: Forth reinvention Bernd Paysan <bernd.paysan@gmx.de> - 2014-02-21 20:51 +0100
        Re: Forth reinvention Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-02-22 09:39 -0600
          Re: Forth reinvention Bernd Paysan <bernd.paysan@gmx.de> - 2014-02-23 02:40 +0100
            Re: Forth reinvention Paul Rubin <no.email@nospam.invalid> - 2014-02-22 19:24 -0800
              Re: Forth reinvention Bernd Paysan <bernd.paysan@gmx.de> - 2014-02-23 22:48 +0100
            Re: Forth reinvention Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-02-23 04:39 -0600
              Re: Forth reinvention Bernd Paysan <bernd.paysan@gmx.de> - 2014-02-23 22:46 +0100
                Re: Forth reinvention Paul Rubin <no.email@nospam.invalid> - 2014-02-23 14:26 -0800
                Re: Forth reinvention Bernd Paysan <bernd.paysan@gmx.de> - 2014-02-24 02:44 +0100
                Re: Forth reinvention Spam@ControlQ.com - 2014-03-03 12:43 -0500
                Re: Forth reinvention Paul Rubin <no.email@nospam.invalid> - 2014-03-03 10:06 -0800
                Re: Forth reinvention Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-02-24 03:59 -0600
  Re: Forth reinvention mike73900@gmail.com - 2014-03-03 14:04 -0800
    Re: Forth reinvention mhx@iae.nl - 2014-03-05 06:59 -0800
      Re: Forth reinvention Matthias Koch <matthias.koch@hot.uni-hannover.de> - 2014-03-05 16:33 +0100
      Re: Forth reinvention Mark Wills <markwills1970@gmail.com> - 2014-03-05 09:08 -0800
        Re: Forth reinvention mhx@iae.nl - 2014-03-05 10:47 -0800
  Re: Forth reinvention AKK <akk@nospam.org> - 2014-03-07 07:30 +0100
    Re: Forth reinvention Lars Brinkhoff <lars.spam@nocrew.org> - 2014-03-07 07:55 +0100
    Re: Forth reinvention albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-03-07 09:29 +0000
      Re: Forth reinvention AKK <akk@nospam.org> - 2014-03-07 12:04 +0100
      Re: Forth reinvention "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-03-07 17:03 -0500
        Re: Forth reinvention Mark Wills <markwills1970@gmail.com> - 2014-03-08 05:31 -0800

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