User Limit Factor and Minimum User Limit Percentage for a Specific Queue

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Minimum User Percentage and User Limit Factor are ways to control how resources get assigned to users within the queues they are utilising. The Min User Percentage is a soft limit on the smallest amount of resources a single user should get access to if they are requesting it.

For a specific queue Minimum User Limit Percentage(MULP) is a soft limit on the smallest amount of resources every user will get.

This MULP is decided on the basis of how many concurrent users we are expecting to run job on a particular queue. Setting this to 10% is ideal as it will give around 10 users to have minimum of 10% of the queue minimum capacity configured.

Setting the config for MULP is also based on the Active and Non Active users. Active users are the users who are requesting for more resources and Non active users are the users who are running their job but not requesting more resources.

Generally the Idea is to calculate the MULP for the active users:

active-user-limit = max(resource-used-by-active-users / active-users, queue-capacity * MULP)

For Example:

5 users, 5 apps, MULP=20, Queue-configured-resource=100

App: a1, a2, a3, a4, a5 

Usr: u1, u2, u3, u4, u5

At the time=T, resource usage: a1=25,a2=20,a3=30,a4=20,a5=5; a1/a2 are active user.

This will give result as 22.5 so the user a2 will get the resources but a1 is already crossed that limit to get the available resources.

For setting User Limit Factor (ULF) that is the max limit a user will get in a particular queue. User Limit Factor is a way to control the max amount of resources that a single user can consume.

User Limit Factor is set as a multiple of the queues minimum capacity where a user limit factor of 1 means the user can consume the entire minimum capacity of the queue.

A common design point that may initially be non-intuitive is creation of queues by workloads and not by applications and then using the user-limit-factor to prevent individual takeover of queues by a single user by using a value of less than 1.0