Processing Units and Virtual Processors
 

Hi,

on redhat linux 5.5 (IBM PPC) os, whenever I am running the command top, it is showing 8 cpu.


Processing Units


Property Current Pending
Minimum 0.1
Assigned 0.8
Maximum 1
Virtual Processors


Property Current Pending
Minimum 1
Assigned 4
Maximum 4


would little bit confused between processing units and virtual processor.

I have assigned 0.8 single cpu , but it is showing 8 vcpu, by pressing 1 , using top command.

Please suggest.

On what hardware?

I think you're assigning 4 cores which have 2 threads each = 8 vcpu.

Hardware Platform is Power 6. with Phuysical 2 Processors with 2 core each processor.

but I would like to know, if I would like to see Singel cpu while using top command by pressing 1 button? is it possible.

because I have assigned 0.8 Processing units, and it is showing 8 vcpu.

So? You have assigned 4 Virtual Processors. This is the setting that controls how many vcpu you see on the LPAR.

I don't know how to track Processing Units on RHEL/PPC. On AIX it's running "nmon" then pressing 'c'.

Hi,

I don't know how things work on Linux, because I only work with AIX where the situation would be the following:

0.8 processing units (the computational power or processing time, so to speak) are divided between 4 virtual CPUs (each has a computational power of 0.2 CPU). Furthermore, the Power5 and Power6 CPUs support 2-way simultaneous multi-threading which means parallel execution of two threads per (virtual) CPU thus creating another level of processor abstraction - the logical CPU. In our case we would have 8 logical CPUs.

In AIX the simultaneous multi-threading (SMT) is controlled by smtctl command, in RHEL the SMT can also be controlled, but requires installation of powerpc-utils (so I've read).

Hope this helps