Multi-threading problem

[heiga]

Hi,

I compiled my C program which included OpenMP directives using icc with -openmp and -parallel options.

When I ran it on a Xeon 3GHz machine (ia32, 2CPU, Vine Linux 3.2, kernel 2.4.31), it worked well (automatically multi-threaded).

However, when I ran it on a Pentium D machine (em64t, 2Core, CentOS 4.2, Linux kernel 2.6.9-34ELsmp), it was not parallelized (single-threaded).
I set OMP_NUM_THREADS=2 and KMP_LIBRARY=turnaround.

Does anyone have any idea to solve this problem?

Thanks in advance.

[TimP]

Did you check /proc/cpuinfo to make sure you are running SMP kernel, and the dual cores are active?

[heiga]

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tim18 wrote:

Did you check /proc/cpuinfo to make sure you are running SMP kernel, and the dual cores are active?

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Thank you very much for your reply :-)

This is my /proc/cpuinfo



processor : 0

vendor_id : GenuineIntel

cpu family : 15

model : 4

model name : Intel Pentium D CPU 2.80GHz

stepping : 4

cpu MHz : 2800.507

cache size : 1024 KB

physical id : 0

siblings : 2

core id : 0

cpu cores : 2

fpu : yes

fpu_exception : yes

cpuid level : 5

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 syscall nx lm pni monitor ds_cpl cid cx16 xtpr

bogomips : 5606.91

clflush size : 64

cache_alignment : 128

address sizes : 36 bits physical, 48 bits virtual

power management:



processor : 1

vendor_id : GenuineIntel

cpu family : 15

model : 4

model name : Intel Pentium D CPU 2.80GHz

stepping : 4

cpu MHz : 2800.507

cache size : 1024 KB

physical id : 0

siblings : 2

core id : 1

cpu cores : 2

fpu : yes

fpu_exception : yes

cpuid level : 5

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 syscall nx lm pni monitor ds_cpl cid cx16 xtpr

bogomips : 5600.04

clflush size : 64

cache_alignment : 128

address sizes : 36 bits physical, 48 bits virtual

power management:



I think 2 cores are active.

And I'm using the CentOS's latest SMP kernel (2.6.9-34.ELsmp).