NUMA enumeration on the Xeon 6250 when cores are turned off

[RajSugathan]

This question is being posted on behalf of a customer with their identification information removed.   This is based on their use of the Intel Xeon 6250 CPUs in a Dual Socket Server with SolarFlare NICs.  The client prioritizes deterministic and highest performance they can yield from the 6250 CPU above everything else.  The CPUs are being used on the S2600BPB server boards from Intel housed in a LOEM chassis/package.

Their questions are:

• When we turn ON/OFF cores, should that be in even numbers per socket? Meaning 2, 4, 6, 8?
• When we turn off core, does numactl respect the core and socket enumeration as defined by the number of cores we have enabled on a socket and not based on the physical cores on the socket?

Here is the usage scenario:

On the servers where we have installed Cascade Lake 6250 processor, we turn OFF cores to speed up (Turbo enabled) to 4.5 GHz and since we cannot maintain Turbo on all cores on both sockets (cooling issue), we shutdown cores.

We originally had the following:

• 2 cores per socket, so essentially 0,1,2,3 [0 and 1 on socket 0 and 2 and 3 on socket 1]

We recently, couple of months back increased the cores we use as follows:

• 3 cores per socket, so essentially 0-5, [0, 1 and 2 on socket 0 and 3, 4 and 5 on socket1]

We have the applications 2 processes pinned to core 1 and core 2 (or so we think). The idea is that we want the applications to be on the same socket to which the Solarflare NIC is mapped, socket 0. However, when we run the stats collection component for Solarflare Onload, it shows that one of the application is on the 2^nd NUMA node.

Hence the question:

• When we turn ON/OFF cores, should that be in even numbers per socket? Meaning 2, 4, 6, 8?
• When we turn off core, does numactl respect the core and socket enumeration as defined by the number of cores we have enabled on a socket and not based on the physical cores on the socket?

[Paul_R_Intel]

Hello RajSugathan, 

Thank you for joining the community,

Thank you very much for all the details about your customer's inquiry, please allow us some time to further analyze the request, and we will get back to you.

Best Regards,

Paul R. 

Intel Customer Support Technician 

For firmware updates and troubleshooting tips, visit: 

https://intel.com/support/serverbios 

[Paul_R_Intel]

Hello RajSugathan, 

Thank you for your patience and time, after reviewing your inquiry we recommend you post the inquiry in the following link so you can get an appropriate resolution:

http://www.intel.com/PerformanceIndex

You can find more information here:

More information:

• Hardware and Software Approach for Using NUMA Systems
• Measuring Performance Impact of NUMA in Multi-Processor Systems (NEW)
• Numatop A tool for memory access locality characterization and analysis

Please let us know if there is anything else that we can do for you, or can we mark the thread as resolved?

Best Regards,

Paul R. 

Intel Customer Support Technician 

For firmware updates and troubleshooting tips, visit: 

https://intel.com/support/serverbios 

[Paul_R_Intel]

Hello RajSugathan,   

 We would like to follow up on your thread. We would like to know if you need further assistance in regards to the details. In case you do, we would highly appreciate if you would let us know.     

Regards  

Paul R.  

Intel Customer Support Technician  

For firmware updates and troubleshooting tips, visit:  

https://intel.com/support/serverbios  

[Paul_R_Intel]

Hello RajSugathan,  

 We would like to follow up on your thread. As we have not heard back from you, we will proceed to mark the thread as resolved.

Thank you for choosing Intel.

Regards  

Paul R.  

Intel Customer Support Technician  

For firmware updates and troubleshooting tips, visit:  

https://intel.com/support/serverbios