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-   -   OpenFOAM 13 AMD quadcore parallel results (http://www.cfd-online.com/Forums/openfoam-solving/59324-openfoam-13-amd-quadcore-parallel-results.html)

msrinath80 November 11, 2007 00:22

Hello OF lovers, Yet anothe
 
Hello OF lovers,

Yet another parallel study, this time on an AMD machine with 8 cores (i.e. two quad-core CPUs). I tested a 3.7 million cell vortex shedding case.

Here is the excerpt from cat /proc/cpuinfo:

[madhavan@neskerd square_cylinder]$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 0
siblings : 4
core id : 0
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3835.39
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 1
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 0
siblings : 4
core id : 1
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3794.05
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 2
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 0
siblings : 4
core id : 2
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3790.04
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 3
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 0
siblings : 4
core id : 3
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3783.81
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 4
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 1
siblings : 4
core id : 0
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3789.98
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 5
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 1
siblings : 4
core id : 1
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3798.47
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 6
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 1
siblings : 4
core id : 2
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3790.00
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

processor : 7
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : Quad-Core AMD Opteron(tm) Processor 2347
stepping : 1
cpu MHz : 1895.313
cache size : 512 KB
physical id : 1
siblings : 4
core id : 3
cpu cores : 4
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 mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 3789.98
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc [6] [7] [8]

Note that the AMD quad core has half the L2 cache (compared to intel) and the fact that it is dedicated. Also it should be mentioned that each physical processor comes with 2 MB L3 cache. Here are the parallel results and a comparison with the previous Intel results as well:

http://www.cfd-online.com/OpenFOAM_D...ges/1/5920.png

Bottom Line: Multi-core CPU offerings from Intel and AMD perform very poorly at memory-bandwidth-limited tasks!

msrinath80 November 11, 2007 00:23

Correction: The title should r
 
Correction: The title should read OpenFOAM 1.4.1 not OpenFOAM 1.3.


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