Product Documentation

Managing CPU Usage

Jul 27, 2011

The CPU utilization management feature can be used to improve the ability of a farm to manage resources and normalize CPU peaks when the farm’s performance becomes limited by CPU-intensive operations. When you enable CPU utilization management, the server manages the share of the CPU allocated to each user. By default, this is an equal share. This prevents one user from impacting the productivity of other users and allows more users to connect to a server. This feature allows you to control the share.

The CPU utilization management feature ensures that CPU resources are equitably shared among users by having the server allocate an equal share of the CPU to each user. This is accomplished by providing CPU reservation and CPU shares.
  • CPU reservation is a percentage of your server’s CPU resource that is available to a user. If all of a reserved allocation is not being used, other users or processes can use the available resource, as needed. Up to 20% of the work capability of a single CPU on a server is always set aside for the local system account and is not available to users.
  • CPU shares are percentages of the CPU time. By default, CPU utilization management allocates four shares for each user. If two users are logged on to a server and the local system account does not need any of the resources on the system, each user receives 50% of the CPU time. If there are four users, each user receives 25% of the CPU time.
Important: The range for CPU share is 1 through 64 percent. For CPU reservation, the total cannot be more than 99%, which represents the entire CPU resource on the computer.

If you enable CPU utilization management, you must disable the Microsoft Dynamic Fair Share Scheduling (DFSS).

Do not enable CPU utilization management on farms or servers that host:
  • CPU-intensive applications that may require a user to have a share of the CPU greater than that allocated to fellow users.
  • Special users who require higher priority access to servers. You can exclude specified users from CPU restrictions.

To enable CPU utilization management

You can enable CPU utilization management using Citrix policy settings. This feature is not enabled by default.

Important:

The Dynamic Fair Share Scheduling (DFSS) aspect of the Windows Remote Desktop Services role is incompatible with CPU utilization management. Ensure that DFSS is disabled on each server where CPU Utilization Management is enabled.

  1. Configure the Citrix policy settings for Memory/CPU > CPU management server level. Choose one of the following settings:
    • Select Fair sharing of CPU between sessions to allocate an equal share of the CPU to each user.
    • Select Preferential Load Balancing to allocate shares based on importance levels.
  2. Continue by applying one or more filters to the policy based on worker groups or organizational units.