I'm doing some benchmarking on a dual 1.8GHz Opteron system
with 4GB of RAM running SuSE 8.2 Pro BETA 9 - and mostly it
looks nice, except for the occasional strange hickups. For example,
I compiled the standard LINPACK Fortran benchmark program. If I
run the same program twice in a row then I sometimes see a *long*
delay in running time. A run with "time" shows that the delay is
not in "user" time but in system:
[1] opteria:~/src/linpack> time out/opteria/linpack.g77
...
xtimes are reported for matrices of order 1000
factor solve total mflops unit ratio
times for array with leading dimension of1001
2.450E+00 0.000E+00 2.450E+00 2.729E+02 7.328E-03 4.375E+01
end of tests -- this version dated 10/12/92
2.520u 0.020s 0:02.53 100.3% 0+0k 0+0io 158pf+0w
---> Ca 273 MFLOPS.
[0] opteria:~/src/linpack> time out/opteria/linpack.g77
Please send the results of this run to:
...
xtimes are reported for matrices of order 1000
factor solve total mflops unit ratio
times for array with leading dimension of1001
2.697E+01 8.000E-02 2.705E+01 2.472E+01 8.091E-02 4.830E+02
end of tests -- this version dated 10/12/92
2.680u 25.370s 0:28.04 100.0% 0+0k 0+0io 158pf+0w
---> Ca 25 MFLOPS, and a whopping 25.37 seconds spent in system-space.
Any suggestions as to why I'm seeing these delays? The machine
is more or less idling...
[0] opteria:~/src/linpack> uname -a
Linux opteria 2.4.21-60-smp #1 SMP Tue Sep 2 11:34:54 UTC 2003 x86_64 unknown
unknown GNU/Linux
I've tried the NUMA kernel, but it doesn't make any difference.
--
Peter Eriksson