Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.forth > #20610

Re: Hosted Forths on multicore machines

Show all headers | View raw

Alex McDonald wrote:

> On Mar 12, 1:05 pm, Alex McDonald <b...@rivadpm.com> wrote:
>> On Mar 12, 1:19 am, Bernd Paysan <bernd.pay...@gmx.de> wrote:
>>
>> > Alex McDonald wrote:
> [snip]
>>
>> > > Forth's traditional "multiuser" feature isn't adequate (PAUSE). It
>> > > simply isn't extendable to multi core machines.
>>
>> > Well, in Gforth's unix/pthread.fs (using Posix threads as multitasker),
>> > PAUSE just maps to sched_yield().
>>
>> That's not useful in a multicore environment. With 4 cores and 4
>> threads, one thread active per core, it will return immediately.
>> Unless there's processor affinity set on the thread, any core can run
>> any thread; all PAUSE does is pester the OS scheduler for no net
>> return. It's only useful in single core/multithread environments; for
>> instance, you release a mutex and want to have other tasks that are
>> waiting get CPU cycles.
>>
> 
> (adding) Or if you have an issue with priority inversion, PAUSE may be
> useful. But it is avoidable with good design.

I don't actually use PAUSE.  It's just there, for "compatibility reasons" 
and it calls sched_yield(), which sometimes may be useful.  I exclusively 
use the <event ->somesignal task event> construct.  It does everything I 
need: It sends an atomic (multi-)message from one task to the other, and I 
can define the sequence point (the event> side is the sender's sequence 
point, the ?events is the receiver's sequence point).

Example: I'm splitting my net2o packet handler code off into a task at the 
moment.  This means you can write event-driven programs that communicate 
with each others through net2o.  It turned out to be a trivial exercise: 
Just put a <event ... task event> wrapper around the packed handler, and if 
there is an event to signal inside the code that handles packets, signal it.  
I need to expose the unsent event queue length, because there's no need to 
send empty queues around (or is this just an optimization issue?  <event 
task event> should really do nothing, and do it fast).

This is still somehow in flux, because <event is not really needed.  
Whatever events come, queue up, and event> sends them.  The only possible 
reason why you might want <event is for nesting, something like

<event ->foo ... <event ->bar a event> ... b event>

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

Back to comp.lang.forth | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-11 14:17 -0700
  Re: Hosted Forths on multicore machines "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2013-03-11 17:41 -0700
    Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 06:38 -0700
  Re: Hosted Forths on multicore machines Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-12 02:19 +0100
    Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 06:05 -0700
      Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 06:34 -0700
        Re: Hosted Forths on multicore machines Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-13 01:51 +0100
      Re: Hosted Forths on multicore machines "Elizabeth D. Rather" <erather@forth.com> - 2013-03-12 09:46 -1000
        Re: Hosted Forths on multicore machines Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-13 11:30 +0100
      Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-13 04:35 -0500
        Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-13 06:55 -0700
          Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-13 09:49 -0500
            Re: Hosted Forths on multicore machines Paul Rubin <no.email@nospam.invalid> - 2013-03-13 08:18 -0700
              Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-13 10:39 -0500
                Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-13 16:36 -0700
                Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-14 03:44 -0500
                Re: Hosted Forths on multicore machines anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-14 09:06 +0000
                Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-14 06:26 -0500
                Re: Hosted Forths on multicore machines anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-14 15:41 +0000
              Re: Hosted Forths on multicore machines Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-14 17:56 +0100
                Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-15 03:26 -0500
                Re: Hosted Forths on multicore machines Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-16 23:11 +0100
  Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-12 05:01 -0500
    Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 06:10 -0700
    Re: Hosted Forths on multicore machines Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-12 17:04 +0100
      Re: Hosted Forths on multicore machines Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-12 11:28 -0500
        Re: Hosted Forths on multicore machines Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-12 19:52 +0100
      Re: Hosted Forths on multicore machines morrimichael@gmail.com - 2013-03-12 10:11 -0700
        Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 11:34 -0700
        Re: Hosted Forths on multicore machines Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-12 19:44 +0100
          Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 13:13 -0700
            Re: Hosted Forths on multicore machines Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-15 15:44 +0100
              Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-15 09:37 -0700
      Re: Hosted Forths on multicore machines Alex McDonald <blog@rivadpm.com> - 2013-03-12 11:37 -0700
        Re: Hosted Forths on multicore machines Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-13 10:46 +0100
  Re: Hosted Forths on multicore machines the_gavino_himself <visphatesjava@gmail.com> - 2013-03-12 15:22 -0700

csiph-web