HP-UX Processor Sets

HP-UX Processor Sets 10
Assigning Applications to Processor Sets
Every process is bound to a processor set in the system. In a multi-threaded process, every
thread has a processor set binding, but not all threads in the process need to be bound to the
same processor set; an application may choose to bind some of its threads to different
processor sets. As a result, a thread may have a different processor set binding than its
process.
The processor set binding inheritance follows the scheduling inheritance rules. A newly
created process and its first thread inherit their processor set binding from the parent process.
A newly created thread in a multi-threaded process inherits its processor set binding from its
creator thread. However, users can explicitly change the processor set binding of a process
to another processor set in the system. When a process is migrated to another processor set,
all its threads are also migrated to the same processor set.
Processor set binding inheritance, along with the ability to dynamically change processor set
binding, enables excellent workload resource management capability. If an application needs
exclusive processor resources, for instance, the application can be migrated to its own
processor set with necessary processor resources. Users can also be restricted to specific
processor sets. When a user logs into the system, migrate the first shell process for the user
to the desired processor set, and from then on, all programs that the user executes will
execute in the same processor set based on the inheritance rules.
A process or thread can also have processor binding that allows the operating system
scheduler to ensure that the thread is always scheduled on the same processor. Note that the
processor set binding of an application has higher precedence than the processor binding.
Therefore, a process or thread cannot be bound to a processor outside its current processor
set. Also, if a process or a thread with processor binding is migrated to another processor set,
the processor binding for the process or thread is reassigned to a processor in the new
processor set.
Ownership and Access Permissions Model
HP-UX Processor Sets configuration and management operations are privileged operations.
The Ownership and Access Permissions model for HP-UX Processor Sets provide necessary
control and flexibility to meet the needs of a range of resource management use models. The
key features of this Ownership and Access Permissions model are as follows: