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Date:      Sun, 05 Dec 1999 20:07:40 -0700
From:      "Russell L. Carter" <rcarter@pinyon.org>
To:        Wes Peters <wes@softweyr.com>
Cc:        Nick Hibma <hibma@skylink.it>, Doug Barton <Doug@gorean.org>, freebsd-hackers@FreeBSD.ORG, rcarter@pinyon.org
Subject:   Re: Basic question about threads and SMP 
Message-ID:  <19991206030740.A376248@pinyon.org>
In-Reply-To: Your message of "Sun, 05 Dec 1999 19:19:17 MST." <384B1D25.DFAF198E@softweyr.com> 

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%Nick Hibma wrote:
%> 
%> Being multi-threaded has almost nothing to do with being
%> multi-processor. Multi-threading means that your application has
%> multiple threads of execution that are able to run simultaneously.
%> 
%> The multi-processing capability of your box means that 2 threads of
%> execution, be it a process or a thread within a process, are executed
%> _literally_ at the same time, and not in simulated concurrency like it
%> happens on a UP box.
%
%Note that this happens ONLY if both threads of execution are processor
%mobile.  If your system supports user-space threads as part of a 
%process and the process can't be split across CPUs, you might as well
%have a UP system.  (Except everything else can run on the other
%processor, so SMP is still a small win.)
%
%This is the situation with threads and SMP in -current.
%

The LinuxThreads port is currently busted for SMP but when it
is fixed it will indeed use multiple processors:


last pid:   395;  load averages:  0.50,  0.11,  0.04                     up 
0+00:13:00  20:00:40
37 processes:  6 running, 31 sleeping
CPU states: 65.8% user,  0.0% nice,  0.0% system,  0.0% interrupt, 34.2% idle
Mem: 8780K Active, 9116K Inact, 19M Wired, 68K Cache, 7000K Buf, 466M Free
Swap: 1024M Total, 1024M Free

  PID USERNAME PRI NICE  SIZE    RES STATE  C   TIME   WCPU    CPU COMMAND
  393 rcarter   31   0   876K   152K CPU1   1   0:01 17.16%  2.39% ex3
  394 rcarter   29   0   876K   152K RUN    0   0:00 15.76%  2.20% ex3
  391 rcarter   30   0   876K   152K RUN    1   0:01 14.71%  2.05% ex3
  395 rcarter   30   0   876K   152K RUN    0   0:01 14.01%  1.95% ex3
  392 rcarter   30   0   876K   152K RUN    0   0:00 13.66%  1.90% ex3


Russell

%-- 
%            "Where am I, and what am I doing in this handbasket?"
%
%Wes Peters                                                         Softweyr LLC
%wes@softweyr.com                                           http://softweyr.com/
%
%
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