Number of CPU / Core

[Philipp Kraus]

Hi

i have tested my new system (2x XEON with 2x4 Cores) with Kernel
2.6.27.21 and set there
CONFIG_NR_CPUS=8

If I run now mpirun with -np 8, the size is only 2. Must I set the -np
flag to the physical CPUs or
to the cores? At university we have 4 systems on each 2 XEONs on each 4
cores => 32 cores.
If I run there mpirun I can set -np from 1 to 32

In my /proc I found 8 cores:

processor : 0 to 7
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Intel(R) Xeon(R) CPU E5405 @ 2.00GHz
stepping : 10
cpu MHz : 1994.999
cache size : 6144 KB
physical id : 0 or 1
siblings : 4
core id : 3
cpu cores : 4
apicid : 7
initial apicid : 7
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm
constant_tsc arch_perfmon pebs bts rep_good nopl pni monitor ds_cpl vmx
tm2 ssse3 cx16 xtpr dca sse4_1 lahf_lm
bogomips : 3990.02
clflush size : 64
cache_alignment : 64
address sizes : 38 bits physical, 48 bits virtual
power management:

Have I forgot any kernel option or config option on mpi?

Thanks

Phil

[Michael Hofmann]

Am 10.06.2009, 14:59 Uhr, schrieb Philipp Kraus

Post by Philipp Kraus
If I run now mpirun with -np 8, the size is only 2. Must I set the -np
flag to the physical CPUs or
to the cores?

Usually, with "-np" one specifies the requested Number of Processes. The
actual number of CPUs or cores should not have an influence on that.
Getting only 2 processes with "-np 8" is strange.


Michael