process affinity problem

From: Taeyoung Hong
Date: Tue Apr 25 2006 - 20:46:55 EST


when "root user" runs 4 HPL(High performance Linpack benchmark program
which is memory intesive, highly dependent on network latency)
processes per node,
"top" shows good cpu affinity and good cpu performance.

but when a general user w/o root privilige runs the same benchmark program,
"top" shows cpu affinity sometimes broken, furthermore sometimes 2 hpl
programs runs the same cpu, after all which gives "poor benchmark
result"

I do not use special kernel parameter on boot, and the followings are
testbed's spec:
system: 4 cpus (2 sockets/ 2 core) opteron 275 blade server
memory nodes: 512MB *2 for a node and 2GB*2 for the other node
OS: RHEL4 update2 w/ kernel 2.6.9-22.ELsmp
network driver: topspin IB implementation

Could you anyone explain about this awkward result?
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