p_online(2) System Calls p_online(2)NAMEp_online - return or change processor operational status
SYNOPSIS
#include <sys/types.h>
#include <sys/processor.h>
int p_online(processorid_t processorid, int flag);
DESCRIPTION
The p_online() function changes or returns the operational status of
processors. The state of the processor specified by the processorid
argument is changed to the state represented by the flag argument.
Legal values for flag are P_STATUS, P_ONLINE, P_OFFLINE, P_NOINTR,
P_FAULTED, P_SPARE, and P_FORCED.
When flag is P_STATUS, no processor status change occurs, but the cur‐
rent processor status is returned.
The P_ONLINE, P_OFFLINE, P_NOINTR, P_FAULTED, and P_SPARE values for
flag refer to valid processor states. The P_OFFLINE, P_SPARE, and
P_FAULTED processor states can be combined with the P_FORCED flag.
A processor in the P_ONLINE state is allowed to process LWPs (light‐
weight processes) and perform system activities. The processor is also
interruptible by I/O devices attached to the system.
A processor in the P_OFFLINE state is not allowed to process LWPs. The
processor is as inactive as possible. If the hardware supports such a
feature, the processor is not interruptible by attached I/O devices.
A processor in the P_NOINTR state is allowed to process LWPs, but it is
not interruptible by attached I/O devices. Typically, interrupts, when
they occur are routed to other processors in the system. Not all sys‐
tems support putting a processor into the P_NOINTR state. It is not
permitted to put all the processors of a system into the P_NOINTR
state. At least one processor must always be available to service sys‐
tem clock interrupts.
A processor in the P_SPARE state is not allowed to process LWPs. In
many respects the P_SPARE state is similiar to the P_OFFLINE state, but
describes a processor that is available for reactivation by management
tools without administrator intervention.
A processor in the P_FAULTED state is not allowed to process LWPs. In
many respects the P_FAULTED state is similiar to the P_OFFLINE state,
but describes a processor that has been diagnosed as faulty. The privi‐
leged caller can change the state of the processor from P_FAULTED to
any of the other states, but since the processor might generate addi‐
tional errors, electing to reactivate such a processor should be care‐
fully considered.
Forced processor state transition can be requested if a new processor
state is specified with the bitwise-inclusive OR of the special
P_FORCED flag. Forcing transition of a processor to the P_OFFLINE,
P_SPARE, or P_FAULTED state revokes processor bindings for all threads
that were previously bound to that processor with processor_bind(2).
There is no guarantee that a forced processor state transition always
succeeds.
Processor numbers are integers, greater than or equal to 0, and are
defined by the hardware platform. Processor numbers are not necessar‐
ily contiguous, but "not too sparse." Processor numbers should always
be printed in decimal.
The maximum possible processorid value can be determined by calling
sysconf(_SC_CPUID_MAX). The list of valid processor numbers can be
determined by calling p_online() with processorid values from 0 to the
maximum returned by sysconf(_SC_CPUID_MAX). The EINVAL error is
returned for invalid processor numbers. See EXAMPLES below.
RETURN VALUES
On successful completion, the value returned is the previous state of
the processor, P_ONLINE, P_OFFLINE, P_NOINTR, P_FAULTED, P_SPARE, or
P_POWEROFF. Otherwise, −1 is returned, the CPU state remains unchanged,
and errno is set to indicate the error.
ERRORS
The p_online() function will fail if:
EBUSY The flag was P_OFFLINE or P_SPARE and the specified
processor is the only on-line processor, there are cur‐
rently LWPs bound to the processor, or the processor
performs some essential function that cannot be per‐
formed by another processor.
The flag was P_NOINTR and the specified processor is
the only interruptible processor in the system, or it
handles interrupts that cannot be handled by another
processor.
The specified processor is powered off and cannot be
powered on because some platform- specific resource is
not available.
EINVAL A non-existent processor ID was specified or flag was
invalid.
The caller is in a non-global zone, the pools facility
is active, and the processor is not a member of the
zone's pool's processor set.
ENOTSUP The specified processor is powered off, and the plat‐
form does not support power on of individual proces‐
sors.
EPERM The flag was not P_STATUS and the {PRIV_SYS_RES_CONFIG}
privilege is not asserted in the effective set of the
calling process.
EXAMPLES
Example 1: List the legal processor numbers.
The following code sample will list the legal processor numbers:
#include <sys/unistd.h>
#include <sys/processor.h>
#include <sys/types.h>
#include <stdio.h>
#include <errno.h>
int
main()
{
processorid_t i, cpuid_max;
cpuid_max = sysconf(_SC_CPUID_MAX);
for (i = 0; i <= cpuid_max; i++) {
if (p_online(i, P_STATUS) != -1)
printf("processor %d present\n", i);
}
return (0);
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOpooladm(1M), psradm(1M), psrinfo(1M), zoneadm(1M), processor_bind(2),
processor_info(2), pset_create(2), sysconf(3C), attributes(5), privi‐
leges(5)SunOS 5.10 16 Aug 2004 p_online(2)
