Kernel uses excessive CPU time *after* giving result.
- To: mathgroup at smc.vnet.net
- Subject: [mg63861] Kernel uses excessive CPU time *after* giving result.
- From: "Dave (from the UK)" <see-my-signature at southminster-branch-line.org.uk>
- Date: Thu, 19 Jan 2006 03:43:24 -0500 (EST)
- Reply-to: Jan-2006 at southminster-branch-line.org.uk
- Sender: owner-wri-mathgroup at wolfram.com
I tried this:
In[1]:= N[1000000!]
5565708
Out[1]= 8.263931688331240 10
on Mathematica 5.2 on my quad processor Sun Ultra 80 (4 x 450 MHz,
Solaris 10). Mathematica gives the result in about 20 seconds, but then
the kernel goes on using 25% of my CPU time (there are 4 processors, so
it is using one of them), *after* returning the result. I can then
calculate something else, but the cpu usage stays pegged at 25% usage.
Here is the output from top a minute or two after the result has been
returned.
load averages: 0.90, 0.75, 0.70
08:11:26
115 processes: 111 sleeping, 4 on cpu
CPU states: % idle, % user, % kernel, % iowait, % swap
Memory: 4096M real, 2473M free, 832M swap in use, 4412M swap free
PID USERNAME LWP PRI NICE SIZE RES STATE TIME CPU COMMAND
22543 drkirkby 3 30 0 0K 0K cpu/1 1:22 24.48% MathKernel
22318 drkirkby 3 59 0 159M 90M sleep 6:45 1.54% mozilla-bin
543 drkirkby 1 59 0 231M 129M cpu/2 160:48 1.23% Xsun
798 drkirkby 2 59 0 92M 30M cpu/0 27:51 0.60% gnome-termin
Here is the output from prstat
sparrow /export/home/drkirkby % prstat
PID USERNAME SIZE RSS STATE PRI NICE TIME CPU PROCESS/NLWP
22543 drkirkby 79M 34M cpu2 20 0 0:01:09 24% MathKernel/3
543 drkirkby 231M 129M sleep 59 0 2:40:47 0.4% Xsun/1
798 drkirkby 92M 30M sleep 59 0 0:27:50 0.4% gnome-terminal/2
22318 drkirkby 159M 90M sleep 59 0 0:06:43 0.1% mozilla-bin/3
If I repeast this using the comment line 'math' rather than the GUI, the
kernel's CPU usage drops back to zero after the result is returned.
--
Dave K
http://www.southminster-branch-line.org.uk/
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