about CPU utilizations using Gadget-2

From: Yan-Rong Li <liyanrong_at_mail.ihep.ac.cn>
Date: Fri, 12 Nov 2010 11:02:30 +0800

  Dear all,

When using Gadget-2, I type the command
mpstat -P ALL 2 5
to display five reports of statistics for all processors at two second
intervals.

The reports is discouraging, of which one line shows

10:46:18 AM CPU %user %nice %sys %iowait %irq %soft
%steal %idle intr/s
10:46:20 AM all 82.70 0.00 16.49 0.00 0.00 0.81
0.00 0.00 10979.50

This means that the system CPU utilization is as high as 17%, while the
user CPU utilization is only 83%.
That is to say, the CPUs just used their 83% times on computations. If I
increase the number of nodes,
the user CPU utilization decreases quickly.

I run the simulation with about 6e5 particles and 24 cores, including a
stars disk and a SMBH.

The simulation is run on a cluster with 3 nodes, which is connected by
10Gbit-Ethernet and MPICH library.
Each node contains 4 Intel Duo CPUs (8cores) in 2.55GHz.

It seems a hardware issue. I want to figure out if Gadget-2 causes this
problem?
Does anybody ever come across this problems?

Cheers,

Yan-Rong
Received on 2010-11-12 04:25:35