HP-UX Processor Sets

The HP-UX Processor Sets allow a multi-processor system to be partitioned into two or more groups of processors (CPU's), so that CPU resources for selected applications or users can be isolated from those of other applications or users. Processor Sets (also known as psets) may be created and reconfigured dynamically by users who have the appropriate privileges. Processor Sets was first shipped as part of the optional Software Pack on HP-UX 11i in October 2001, and is available in the Kernel from HP-UX 11i v1.6 by default. Where Processor Sets is available in HP-UX, it is supported on all multi-processor systems. Processor Sets is a full-functioning stand-alone feature, but psets functionality is also fully supported by and integrated with the optionally available Process Resource Manager (PRM) product.

Summary of Change

The Processor Sets functionality consists of several system calls, one new library call, the underlying kernel support for those calls, several changed system calls, one changed library call, several changed commands, and one new command.

The new Processor Sets system calls are:

The changed Processor Sets system calls are:

The new Processor Sets library call is pthread_pset_bind_np() which is documented in the existing pthread_processor_bind_np(3T) manpage.

To support the Processor Sets functionality, several commands have been enhanced and a new command psrset(1M) was introduced.

The following existing commands were enhanced to support Processor Sets functionality:

Details of Change

The new Processor Sets system calls are:

pset_create: Create a pset with no processors. pset_assign() is used to add CPU's to a pset.
pset_destroy: Destroy a specific pset.
pset_assign: Place a CPU in a processor set. Because every processor is in a pset (initially the "default pset"), pset_assign moves a CPU from one pset to another.
pset_bind: Bind selected thread(s) or process(es) to a specific pset.
pset_getattr: Get the attributes for a pset. Some example pset attributes are the owner of the pset, or the access permissions for the pset.
pset_setattr: Set the attributes for a pset.
pset_ctl: Query pset information, such as the pset binding of the calling thread, or the number of CPU's in the pset.

The changed Processor Sets system calls:

mpctl

Updated to return pset-specific information by default. For example, applications running within a pset only have access to the CPU's in that pset. Therefore, determining the number of CPU's in the whole system is typically less relevant to the application, than determining the number of CPU's in its pset, so this latter is now the default. The mpctl command returns system-wide information through use of a new parameter.




	NOTE: Note that mpctl behavior on HP-UX 11i v1.6 is identical to that of HP-UX 11i with psets installed.

sysconf

Updated to include pset information.

rtsched

Updated to support psets. A real-time thread only runs, or competes for CPU's, within its pset.

pstat

Updated to include pset information. For example, information regarding the pstat_getpset() can now be found in the manpage for pstat, as pset information has been added.

The new Processor Sets library call is:

pthread_pset_bind_np: /added to support psets and pset binding.

The changed Processor Sets commands are:

mpsched

A new option -f has been introduced in mpsched to force the operation of binding of a process to a processor if the HP Process Resource Manager is installed and configured.

If mpsched is used without -f option in the presence of HP PRM to bind a process to a processor, then an error message is displayed. In order for this binding operation to go through, the -f option needs to be used along with binding options of mpsched. Moreover, in the presence of Processor Sets functionality if mpsched is used to bind a process to a processor or a ldom, across psets, then it prints the appropriate error message.

ps

The ps command has been enhanced to support the Processor Sets functionality by adding two new options -z and -Z. These two new options are added to enable the users to know to which pset a pid is bound, and to list all the pids in a given pset.

The description of the new options are:

The -z option adds a column "pset" before column "prmgrp/prmid". If prmgrp and prmid are not present adds a column "pset" before the "pid" column. The kernel pset, where all the kernel processes run, is displayed as "KERN". Basically this option maps the pid with a pset to which it is bound. This option doesn't take any arguments.
The -Z option lists all the process ids bound to a specified pset. This option takes a list of pset ids as arguments. If prmgrp and prmid are not present, this option adds a pset column before the pid column in the listing.

sar

The sar command has been enhanced to support Processor Sets functionality by adding two new options -p and -P.

The description of the new options are:

The -P option adds a column "pset" to display the CPU mapping to pset, whenever the -M option (per processor information) is specified.
Also when the option -p is specified, it displays only the information of the specified pset. Without -p option sar displays the information for the whole system.
NOTE: These two options should be used along with -u, -q and -a options. If these new options are used with any other options, processor set information is not displayed.

top

The top command has been enhanced to support the Processor Sets functionality by adding two new options -p and -P.

The description of the new options are:

The -p option takes the pset id as argument and displays load averages and process state break down for system and processor set pset_id. This option shows only the processes running on the processor set pset_id.
The -P option displays a column PSET before column CPU for individual CPU information. Also it displays a column PSET, before the column CPU for each process information.

uptime

The uptime command has been enhanced to support the Processor Sets functionality by adding one new option -p.

The -p option can be given with or without an argument. If given with an argument, it takes pset id as an argument. The -p option prints the current time, the length of time the system has been up, and the number of users logged on to the system in the first line of the output. The load averages over the last 1, 5, and 15 minutes for the psets given in the command line, pset_list, are displayed in the subsequent lines. If no arguments are given, the load averages are displayed for all the psets in the system. If pset id of an empty pset is given in the command line, corresponding message is displayed. The -p option cannot be used with other options.

id

The -P option of the id command has been enhanced to display correct prmid in the presence of Processor Sets functionality. Also, the id command has been modified to return non-zero return values on error conditions and displays an usage message on incorrect usage.

rtsched

Updated to support psets. A real-time thread only runs, or competes for CPU's, within its pset.

The new Processor Sets command is:

psrset

The psrset command is new and was developed for the Processor Sets functionality. This command creates and manages processor sets on a HP-UX system supporting Processor Sets functionality. The psrset command supports different options which a user can use to perform the following tasks:

Assign a processor to a given pset.
Bind a pid to a given pset.
Destroy the specified pset.
Execute a command on a given pset.
Bind all the processes belonging to a process group to a given pset.
Display all the processors and pset attributes for given pset or all psets in the system.
Enable external I/O interrupts for all processors in a given pset.
Disable external I/O interrupts for all processors in a given pset.
Display the pset-processor mapping for a given processor or for all processors in the system.
Display the pid - pset mapping for a given pid or for all pids in the system.
Remove the specified processor from the pset and assign it to the default pset.
Change the attributes of a given pset.
Unbind a given pid from a pset to which it is currently bound.
Bind all the processes owned by a user id to the specified pset.

Impact

Not applicable.

Compatibility

The behavior of mpctl has evolved as described above, though it is the same as on HP-UX 11i with psets installed.

There are no command compatibility issues because the enhanced functionality in each command is accommodated in new options and the behavior of the existing options is unchanged.

Performance

Not applicable.

Obsolescence

Not applicable.

Documentation

The manpages for all new and updated system and library calls, and commands, are supplied with the system.

A new manpage for command psrset(1M) is introduced in HP-UX 11i v1.6, see this manpage for details.

The manpages of the following commands have been updated by adding the description of the new functionality introduced:

getconf(1)

The following line has been added in the supported inquiries section :

PSET_SUPPORT

mpsched(1)

The SYNOPSIS section of has been changed. The description of the -c and -l have been changed. The description for the new -f option has been added.

ps(1)

The SYNOPSIS section has been changed. The description for the -z and -Z options has been added.

sar(1M)

The SYNOPSIS section has been changed. The descriptions of the -u and -q options have been changed. The description for the new -p and -P options has been added.

top(1)

The SYNOPSIS section has been changed. In the Display Description, the PSET field has been added. The description for the new -p and -P options has been added.

uptime(1)

The SYNOPSIS section has been changed. The description for the new -p option has been added. In the EXAMPLES section, an example to illustrate the use of the -p option has been included.

id(1)