Plan CPU and Memory Allocations

There are two main approaches to modifying resource allocations:

• All resources allocated – You move resources from domains to other domains, and ensure that all resources are allocated.

• Some resources are unallocated – You allocate less than the maximum available cores and memory for a compute node. Any unused cores are considered parked cores and are not counted for licensing purposes. However, parked cores are added to the logical CPU and memory repository. If you have Root Domains, you can later allocate the repository resources to I/O Domains. See Park Cores and Memory.

Depending on which command you use to view domain resources, you might need to convert socket, core, and VCPU values.

• Use these specifications for SuperCluster T5-8.

  • 1 socket = 16 cores

  • 1 core = 8 VCPUs

• Use these specifications for SuperCluster M6-32.

  • 1 socket = 12 cores

  • 1 core = 8 VCPUs

1. Identify the current resource configuration for each compute node.

   To display the current configuration, see one of these procedures:

   • Display the Current Domain Configuration (osc-setcoremem)

   • Display the Current Domain Configuration (ldm)

   In this example, one compute node on a SuperCluster T5-8 Full-Rack has five dedicated domains and one Root Domain.

   Domain Domain Type Cores Before Memory Before (GB) primary Dedicated 32 512 ssccn2-dom1 Dedicated 16 256 ssccn2-dom2 Dedicated 16 256 ssccn2-dom3 Dedicated 16 256 ssccn2-dom4 Dedicated 16 256 ssccn2-dom5 Root 4 64 Unallocated Resources 28 448

2. Add the domain resources together to determine the total number of resources.

   Calculating the total amount of CPU and memory resources gives you a starting point for determining your resource plan.

   While identifying resources, keep these points in mind:

   • Root Domain resources – Are a small amount of resources that are reserved for the exclusive use of Root Domains (4 cores and 64 GB of memory in this example). Do not factor these resources into your plan.

   • Unallocated resources – These resources are placed in the CPU and memory repositories when Root Domains are created, or by leaving some resources unallocated when you use the osc-setcoremem command.

   In this example, the resources for the dedicated domains and the unallocated resources are summed to provide total resources. The Root Domain resources are not included in total resources.

   Domain Domain Type Cores Before Memory Before (GB) primary Dedicated 32 512 ssccn2-dom1 Dedicated 16 256 ssccn2-dom2 Dedicated 16 256 ssccn2-dom3 Dedicated 16 256 ssccn2-dom4 Dedicated 16 256 ssccn2-dom5 Root n/a n/a Unallocated Resources 28 448 Total Resources 124 1984

3. Based on your site requirements, and the type and number of domains on SuperCluster, decide how to allocate CPU and memory for each domain.

   This is an example of a plan that reduces resources for primary, ssccn2-dom2, ssccn2-dom4, so that the resources are parked (unallocated). The parked resources can later be used by I/O Domains.

   The total resources for before and after columns should match. This check ensures that all resources are accounted for in your plan.

   Domain Domain Type Cores Before Cores After Memory Before (GB) Memory After (GB) primary Dedicated 32 16 512 256 ssccn2-dom1 Dedicated 16 16 256 256 ssccn2-dom2 Dedicated 16 8 256 64 ssccn2-dom3 Dedicated 16 16 256 256 ssccn2-dom4 Dedicated 16 4 256 64 ssccn2-dom5 Root n/a n/a n/a n/a Unallocated Resources 28 64 448 1088 Total Resources 124 124 1984 1984

4. Consider your next action:

   • Change resource allocations at the socket granularity level.

     See Change CPU/Memory Allocations (Socket Granularity)

   • Change resource allocations at the core granularity level.

     . See Change CPU/Memory Allocations (Core Granularity)

   • Increase unallocated resources.

     See Park Cores and Memory

Related Information

• osc-setcoremem Overview

• Supported Domain Configurations

• Display the Current Domain Configuration (osc-setcoremem)

• Display the Current Domain Configuration (ldm)

• Change CPU/Memory Allocations (Socket Granularity)

• Change CPU/Memory Allocations (Core Granularity)

• Park Cores and Memory