class_x.yml

# roles/sysctl/tasks/class_x.yml

- name: do some sysctl stuff for performance cluster
  sysctl: name="net.ipv4.ip_forward" value=1

class_y.yml

# roles/sysctl/tasks/class_y.yml

- name: do some sysctl stuff for performance cluster
  sysctl: name="net.ipv4.ip_forward" value=0

inventory

[perf-cluster1]
host[1-6]

[perf-cluster1]
host[7-8]

[class-x]
host[1-2]

[class-y]
host[3-6]

[class-z]
host[7-8]

play.yml

---
- hosts: class-x

  roles: 
    - sysctl/class_x

- hosts: class-y

  roles:
    - sysctl/class_y