J06.12 Release Version Update Compendium

3 Application Development Products
Support for Explicit Control over the Placement of Processes Within
Multi-Core Processors
Three new Guardian procedure calls and a new IPUCOM command interface are introduced for
HP NonStop multi-core systems. This new feature allows explicit assignment of user processes to
specific Instruction Processing Units (i.e. IPU “cores”) within each NonStop Operating System
(NSOS) logical processor. During normal operation, the NSOS Process Scheduler uses a number
of factors to dynamically determine which IPU to use each time a process is ready to execute.
However, some user environments have been identified where explicitly controlling the IPU in which
specific user processes are run might be useful to minimize IPU idle time and latency. Use of these
new interfaces restricts the operation of the Process Scheduler by statically assigning a process to
a single IPU which can result in a negative overall performance impact if the characteristics and
interactions of the affected user processes are not very well understood within the context of the
overall workload.
• Guardian Procedure Calls
IPUAFFINITY_SET_
This procedure call associates a process with a given Instruction Processing Unit (IPU).
The Process Scheduler will not move this process after the association has been set (without
another call to this procedure).
◦
◦ IPUAFFINITY_CONTROL_
This procedure call controls scheduling features not associated with a single process. It
can also clear all those settings as well as all the associations between process and IPU.
◦ IPUAFFINITY_GET_
This procedure call returns the current IPU number associated with a process. This is the
IPU number currently assigned by the Process Scheduler or, if in effect, the IPU number
set by IPUAFFINITY_SET_.
• IPUCOM Command
◦ IPUCOM is a command line interface that is used to set, reset, or display the IPU associated
with a process. It can also be used to control scheduling features not associated with a
single process.
Migration Considerations
• This feature is only supported on HP Integrity NonStop multi-core systems running J06.12 or
later RVUs.
• IPUAFFINITY_SET_ requires process owner, group manager, or super ID privileges, or the
caller must be in the affected process. IPUAFFINITY_CONTROL_ requires super ID privileges.
• These processes cannot be explicity controlled: Interrupt Processes (IPs) other than the TSMSGIP,
TSSTRIP, or TSCOMIP, and Auxiliary Processes (APs).
Fallback Considerations
None.
12 Application Development Products