LSF Version 7.3 - Using Platform LSF HPC

About HP-UX Psets
HP-UX processor sets (psets) are available as an optional software product for HP-UX
11i Superdome multiprocessor systems. A pset is a set of active processors group for the
exclusive access of the application assigned to the set. A pset manages processor
resources among applications and users.
The operating system restricts applications to run only on the processors in their
assigned psets. Processes bound to a pset can only run on the CPUs belonging to that
pset, so applications assigned to different psets do not contend for processor resources.
A newly created pset initially has no processors assigned to it.
Each running application in the system is bound to some pset, which defines the
processors that the application can run on.
A pset defines a scheduling allocation domain that restricts applications to run only on
the processors in its assigned pset.
At system startup, the HP-UX system is automatically configured with one system
default pset to which all enabled processors are assigned. Processor 0 is always assigned
to the default pset. All users in the system can access the default pset.
See the HP-UX 11i system administration documentation for information about
defining and managing psets.
How LSF uses psets
On HP-UX 11i Superdome multiprocessor systems, psets can be created and
deallocated dynamically out of available machine resources. The pset provides processor
isolation, so that a job requiring a specific number of CPUs only run on those CPUs.
Processor distance is a value used to measure how fast the process running on one
processor access local memory of another processor. The bigger the value is, the slower
memory access is. For example, the processor distance of two processes within one cell
is less than that of two processes between cells.
When creating a pset for the job, LSF uses a best-fit algorithm for pset allocation to
choose processors as close as possible to each other. LSF attempts to choose the set of
processors with the smallest processor distance.
LSF makes use of HP-UX processor sets (psets) to create an efficient execution
environment that allows a mix of users and jobs to coexist in the HP Superdome cell-
based architecture.
When a job is submitted, LSF:
◆ Chooses the best CPUs based on job resource requirements (number of processors
requested and pset topology)
◆ Creates a pset for the job. The operating system assigns a unique pset identifier (pset
ID) to it.
◆ Places the job processes in the pset when the job starts running