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rad_attach_pid(3)
NAME
rad_attach_pid, rad_bind_pid - Attaches or binds a process to a Resource
Affinity Domain by process ID (libnuma library)
SYNOPSIS
#include <numa.h>
int rad_attach_pid(
pid_t pid,
radset_t radset,
ulong_t flags );
int rad_bind_pid(
pid_t pid,
radset_t radset,
ulong_t flags );
PARAMETERS
pid Identifies the process to be attached or bound to the specified set of
Resource Affinity Domains (RADs).
radset
Specifies the RAD set to which the process will be attached or bound.
flags
Specifies options (a bit mask) that affect the attachment or binding
operation. See DESCRIPTION for details.
DESCRIPTION
The rad_attach_pid() function attaches the process specified by pid to the
set of RADs specified by radset.
The rad_bind_pid() function binds the process specified by pid to the set
of RADs specified by radset.
While both functions assign a "home" RAD for the process, an attach
operation allows remote execution on other RADs while a bind operation
restricts execution to the "home" RAD. For both functions, if the pid
argument is NULL, the call is self-directed. That is, the function behaves
as if pid identified the calling process.
The memory allocation policy for the process will be set to MPOL_THREAD.
The home RAD for the process will be selected by the system scheduler from
among the RADs included in radset and will be based on current system load
balance and the flags argument. The overflow set (mattr_radset) for the
process will be set to radset. If the process has multiple threads, then
any of those threads that have inherited the process's default memory
allocation policy will be attached or bound by using the same new memory
allocation policy as used for the process that contains them.
The threads of the specified process will be scheduled on one of the CPUs
associated with the selected RAD, except for threads that have been
explicitly bound to some other processor. The CPU will be selected by the
scheduler from among those CPUs associated with the selected RAD in the
process's partition. (This partition might not be the same as the caller's
partition if the caller has appropriate privilege.) The selection will be
determined by the loading of the CPUs.
The following options are defined for the flags argument:
RAD_NO_INHERIT
Any processes later forked by the specified process can be assigned to
any RAD on the system, and might not inherit its parent's home RAD
assignment; that is, the child processes might not be assigned to the
same home RAD as the parent. This allows the system to assign a home
RAD to the child process depending on available resources.
Normally, child processes do inherit the assignments and attributes of
the parent process.
By default, processes that are later forked by the process specified in
a rad_attach_pid() or rad_bind_pid() call inherit the RAD assignment of
their parent.
RAD_INSIST
The requested attachments or bindings are mandatory. If this option is
not set, the system will consider the request to be a "hint" and may
take no action for the specified process or, if applicable, any child
processes that the specified process contains.
RAD_SMALLMEM
The process has small memory requirements, so the system should favor
(for the home RAD) those RADs with light CPU loads, independent of
their available memory.
RAD_LARGEMEM
The process has large memory requirements, so the system should favor
(for the home RAD) those RADs with more available memory, independent
of their CPU loads.
RAD_MIGRATE
Arrange for existing memory of the process to be migrated to the new
home RAD. If RAD_MIGRATE is omitted, only newly allocated pages will
be allocated on the new home RAD. Existing pages will migrate if or
when they experience a high rate of remote cache misses. Migration will
occur only for pages in memory objects that have inherited the
process's default memory allocation policy.
RAD_WAIT
Wait for the requested memory migration to be completed. Effectively,
this specifies "migrate now!".
If the caller does not have partition administration privilege and if pid
is not in the caller's partition, or if the radset argument contains RADs
that are not in the caller's partition, an error will be returned.
The value for the radset argument could be obtained from a prior call to
nloc() that assigned or migrated the process to a RAD close or closer to a
particular resource. When obtained this way, radset will contain only the
RADs in the caller's partition at the time of the nloc() call. The
partition configuration could change between a call to nloc() and a
subsequent call to rad_attach_pid() or rad_bind_pid(), resulting in an
error. This error is not likely to occur often, but a robust application
should handle it.
RETURN VALUES
0 Success.
-1 Failure. In this case, the functions set errno to indicate the error.
ERRORS
If either of these functions fail, errno is set to one of the following
values for the condition specified:
[EBUSY]
RAD_INSIST and RAD_MIGRATE were specified and the specified process
cannot be migrated for some reason. For example, memory is wired
(locked) on the process's current RAD.
[EFAULT]
The radset argument points to an invalid address.
[EINVAL]
One or more of the RADs in the radset argument or options in the flags
argument are invalid.
[ENOMEM]
RAD_INSIST and RAD_MIGRATE were specified and the specified process
cannot be migrated because insufficient memory exists on the specified
RAD set.
[EPERM]
The real or effective user ID of the caller does not match the real or
effective user ID of the specified process, or the caller does not have
appropriate privileges to assign processes to RADs.
[ESRCH]
The process specified by pid does not exist.
SEE ALSO
Functions: nloc(3), rad_detach_pid(3)
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