MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Re: Illusory Multicore Support in 5.2?

  • To: mathgroup at
  • Subject: [mg66056] Re: [mg66046] Re: Illusory Multicore Support in 5.2?
  • From: George Woodrow III <georgevw3 at>
  • Date: Fri, 28 Apr 2006 06:32:32 -0400 (EDT)
  • References: <> <e2pp8k$su2$> <e2q0o1$1t7$> <>
  • Sender: owner-wri-mathgroup at

Using Mathematica 5.2.2 on OS X 10.4.6 PowerMac QuadCore. I haev 8  
Gbytes RAM

I ran Activity monitor to see the CPU usage graphically.

I executed the following in 1 cell so that all the computations would  
be passed to the kernel at the same time:

N[Ï?, 100000000]; // Timing
N[ϵ, 100000000]; // Timing
N[Sqrt[2], 100000000]; // Timing

(doing just 1000000 places returned too fast -- pi in 3.4 seconds and  
the others much faster. I asked for 100 times the decimal places so  
the program would run for a while.)

I would expect one thread per computation -- they are independent.  
Instead, I get 100% of one CPU all the time. The CPU switches from  
time to time -- probably the OS resolving usage/heat issues.

The Activity monitor reposts MathKernel using 3 threads and 99.9% of  
the CPU -- the max is 400%. I can get more than 200% of CPU usage  
running iTunes's visualliser with all the options cranked up, or Sims  
2. There appears to be no problem with the OS distributing a multi- 
threaded app among the processors.

The good news is that there is no slowdown from the rest of my apps:  
the OS distributes the usage among running apps very well. the Bad  
News is that Mathematica seems to be using only one CPU at a time.


On Apr 27, 2006, at 5:35 AM, Chris Chiasson wrote:

> Do the posters in this thread happen to be running a 32 bit version of
> Mathematica?

  • Prev by Date: Re: Re: Illusory Multicore Support in 5.2?
  • Next by Date: Re: Re: Calling .exe with Arguments - Run[] Issue
  • Previous by thread: Re: Re: Illusory Multicore Support in 5.2?
  • Next by thread: Re: Illusory Multicore Support in 5.2?