Linux CPU information

Rambo · 20-09-2013 10:55AM #1

Hi i am trying to write a script to get the number of cores on a linux box
on Redhat enterprise 6 no problem just issue the command nproc

and it gives me the number of cores from cpu

but we also have older version of Redhat this command does not exist

I have tried this

top -b -n 1 | grep CPU | wc -l

cat /proc/cpuinfo | grep "processor" | wc -l

but none of these count for hyper threading cores

I need core count only

Skrynesaver · 20-09-2013 11:33AM

cat /proc/cpuinfo | grep 'core id'

Rambo · 20-09-2013 12:15PM

Skrynesaver wrote: »

cat /proc/cpuinfo | grep 'core id'

try that on a Red Hat Enterprise Linux AS release 3

no output

Skrynesaver · 20-09-2013 12:17PM

Don't have an RHEL3 box around I'm afraid...

syklops · 20-09-2013 02:29PM

Core ID isnt in cpuinfo in RHEL 3.

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/4/html/Reference_Guide/s2-proc-cpuinfo.html

croo · 20-09-2013 03:22PM

My i7 has 4 cores but 8 CPU .. what do you want to count?
If it were CPU then there will be an entry for each in the /proc/cpuinfo mentioned already so just count the number of "processor"s there are...

cat /proc/cpuinfo | grep "processor" | wc -l

should do it.
If you wanted physical cores then there would be a little more work.

Rambo · 20-09-2013 03:44PM

croo wrote: »
My i7 has 4 cores but 8 CPU .. what do you want to count?
If it were CPU then there will be an entry for each in the /proc/cpuinfo mentioned already so just count the number of "processor"s there are...
cat /proc/cpuinfo | grep "processor" | wc -l
should do it.
If you wanted physical cores then there would be a little more work.

yes physical cores I need

niallb · 20-09-2013 03:51PM

OP does want physical cores though.
Might save yourself time by just getting the cpu model name and looking it up on the manufacturer's website.
You can return the correct number of cores from your script using a lookup table.
Check for kernel 2.4.21 and return kludge()
It's clumsy, dirty and might just fix your problem faster than solving it.

CrinkElite · 20-09-2013 04:11PM

Have you tried "lscpu"? I'm not on a linux box at the moment but it may have what you're looking for.

Rambo · 20-09-2013 04:22PM

CrinkElite wrote: »

Have you tried "lscpu"? I'm not on a linux box at the moment but it may have what you're looking for.

yes on Redhat 6 Enterprise

here the output

[root@localhost ~]# lscpu
Architecture: x86_64
CPU op-mode(s): 64-bit
CPU(s): 2
Thread(s) per core: 1
Core(s) per socket: 1
CPU socket(s): 2
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 29
Stepping: 1
CPU MHz: 2400.085
L1d cache: 32K
L1i cache: 32K
L2 cache: 3072K
L3 cache: 12288K
NUMA node0 CPU(s): 0,1

but on older linux dist this command does not exists

croo · 20-09-2013 05:29PM

Rambo wrote: »

yes physical cores I need

ok. so what is in the /proc/cpuinfo file?
I'm running ubuntu right now so it's probably a little different but to get the number of cores I would just count the number of different core id. From the link skylops provided I think the "core id" is called "physical id" so ...

cat /proc/cpuinfo | grep "physical id" | uniq -c | wc -l

should provide the number of cores.

PS since it's an odl RHEL perhaps just show us what IS actually in the cpuinfo file?

niallb · 21-09-2013 02:20PM

It's a 2.4 kernel, so it's quite different.
I only have RHEL3 still running on a virtual machine for compatibility with an old development environment when necessary, but here's the output from that:

processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 2
model name : QEMU Virtual CPU version 0.9.1
physical id : 255
siblings : 1
runqueue : 0
stepping : 3
cpu MHz : 1994.971
cache size : 2048 KB
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx lm sse3
bogomips : 3971.48
clflush size : 64
address sizes : 40 bits physical, 48 bits virtual
power management:

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