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I have a Beowulf Super Computer consisting of (4) Dell PowerEdge R610 each with 2xQuad Core Xeon E5640 processors @ 2.4Ghz

I also have MPIv3.2 installed for parallel messaging.

The master node has the nfs server running that the other 3 compute nodes mount at boot for common home directories and execution space.

Here is the output of lscpu:

mpiuser@PowerEdge-R610-LCN0:~$ sudo lscpu | more
[sudo] password for mpiuser:
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                16
On-line CPU(s) list:   0-15
Thread(s) per core:    2
Core(s) per socket:    4
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 44
Model name:            Intel(R) Xeon(R) CPU           E5620  @ 2.40GHz
Stepping:              2
CPU MHz:               2393.915
BogoMIPS:              4787.83
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              12288K
NUMA node0 CPU(s):     0,2,4,6,8,10,12,14
NUMA node1 CPU(s):     1,3,5,7,9,11,13,15
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 pdpe1g
b rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_t
sc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3
 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 popcnt aes lahf_lm tpr_shadow vnmi flexpr
iority ept vpid dtherm ida arat
mpiuser@PowerEdge-R610-LCN0:~$

As you can see (I believe this is true) that the information relates only to this server.

Now either there is a CPU core limit in Ubuntu 16.04 (like RHEL @ 16 without licensing) or lscpu does not record the cores on the other (3) compute nodes.

Question:

Is there a way for the Linux (Ubuntu 16.04) OS to recognize all 32 cores (64 logical CPUs) or is this a limitation of lscpu?

Is there a way to measure is the OS is using all 32 cores?

Byte Commander
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Don Masters
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    see https://askubuntu.com/questions/158555/how-many-maximum-cpus-does-ubuntu-support-by-default 12.04 could handle 256 cores by default and 4096 with kernel tweaks. – Rinzwind Apr 15 '17 at 00:45

1 Answers1

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That's reporting the number of cores (doubled with hyperthreading) on a single machine.

The Xeon E5640 has 4 cores, which is doubled to 8 with hyperthreading. Since there are two Xeon E5640s, the total number of reported cores is 16.

Chai T. Rex
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  • Is there software that I can add to make this Linux version (Ubuntu 16.04 LTS) cluster aware?, meaning that the master node is aware of the cores on the other compute nodes? – Don Masters Apr 16 '17 at 19:24
  • I don't know much about Beowulf. According to [the Debian guide to starting a Beowulf cluster](https://wiki.debian.org/StartaBeowulf#Symmetric_MultiProcessing), something called "Mosix is a kernel patch and set of utilities which make a cluster of machines appear as a single multiprocessor machine with shared memory". That might or might not be what you want. There may be a Beowulf-specific way of finding the information that's easier. – Chai T. Rex Apr 17 '17 at 18:11