HP-UX HB v13.00 Ch-19 - PRM

HP-UX Handbook – Rev 13.00 Page 4 (of 31)
Chapter 19 Process Resource Manager (PRM)
October 29, 2013
Introduction
Process Resource Manager (PRM) is a resource management tool used to control the amount of
resources that processes use during peak system load (at 100% CPU resource or 100% memory
resource). PRM can guarantee a minimum allocation of system resources available to a group of
processes through the use of PRM groups.
A PRM group is a collection of users and applications that are joined together and assigned
certain amounts of CPU and memory resource. The two types of PRM groups are FSS PRM
groups and PSET PRM groups. An FSS PRM group is the traditional PRM group, whose CPU
entitlement is specified in shares. This group uses the Fair Share Scheduler (FSS) in the HP-UX
kernel within the system’s default processor set (PSET). A PSET PRM group is a PRM group
whose CPU entitlement is specified by assigning it a subset of the system’s cores (PSET). (A
core is the actual data-processing engine within a processor. A single processor might have
multiple cores. A core might support multiple execution threads.) Processes in a PSET have
equal access to CPU cycles on their assigned cores through the HP-UX standard scheduler.
PRM’s Resource Managers
PRM has four resource managers:
CPU (CPU percentage)
Ensures that each PRM group is granted at least its allocation of CPU resources. Optionally
for FSS PRM groups, this resource manager ensures no more than its capped amount of
CPU resources. For PSET PRM groups, processes are capped on CPU resource usage by
the number of cores assigned to the group.
MEM (memory)
Can manage both private memory and shared memory.
 For private memory:
Ensures that each PRM group is granted at least its share, but (optionally) no more
than its capped amount of memory. You can also specify memory shares be
isolated so that a group’s assigned memory shares cannot be loaned out to, or
borrowed from, other groups.
 For shared memory:
Ensures a PRM group is allocated a minimum number of megabytes for use as
shared memory.
DISK (disk bandwidth)
Ensures that each FSS PRM group is granted at least its share of disk bandwidth. PRM disk
bandwidth management can only control disks that are mounted and under the control of
HP's Logical Manager (LVM) or VERITAS Volume Manager(TM) (VxVM(R)).
PSET PRM groups are treated as part of PRM_SYS (PRMID 0) for disk bandwidth