nsg_init - Look up or create a NUMA Scheduling Group (libnuma
ulong_t flags );
Specifies the key that identifies the NUMA Scheduling
Group (NSG). This value may be one of the following: An
arbitrary binary value other than zero If the NSG_GETBYPID
flag is set, the process ID of a member process of the
requested NSG Specifies lookup or creation flags. The following
options are defined for the flags argument: Creates
the NSG and return its identifier. If NSG_CREATE and
NSG_EXCL are both specified, an error will be returned if
the NSG identified by key already exists. If set, then
the key parameter is the process ID (pid_t) of a process
that is currently a member of the requested NSG. Otherwise,
key is an arbitrary binary value that identifies the
If the NSG identified by key does not already
exist, an error will be returned unless the
NSG_CREATE flag is specified. If the NSG_GETBYPID
flag is set and the process identified by the value
of key does not exist, an error is returned.
If both the NSG_CREATE and the NSG_GETBYPID flags
are set, and the process identified by the value of
key exists but is not currently a member of an NSG,
a new NSG will be created using the value of key
(the process's ID) and the process will be attached
to the new NSG. This establishes the "home RAD" of
the process as the home RAD for the NSG. A child
process will not inherit the NSG of the parent and,
therefore, can be assigned to any eligible RAD on
the system. This flag is valid only if both
NSG_CREATE and NSG_GETBYPID are also specified.
The NSG will be marked for automatic deletion when
the nsg_perm.nattach member of the associated
nsgid_ds structure transitions from nonzero to
The nsg_init() function looks up and possibly creates the
NSG identified by the key parameter. The flags parameter
supplies options for the lookup or create operation.
After creating a new NSG, the nsg_init() function initializes
an associated nsgid_ds structure as follows: The
nsg_perm.cuid and nsg_perm.uid members are set equal to
the effective user ID of the calling process. The
nsg_perm.cgid and nsg_perm.gid members are set equal to
the effective group ID of the calling process. The low
order nine bits of nsg_perm.mode are set equal to the low
order nine bits of flags. The nsg_perm.nattach member is
set to zero (or 1 if NSG_GETBYPID is specified in flags).
The nsg_perm.mode permissions control operations on NSGs
as follows: Write permission is required to destroy the
NSG or to set the owner IDs and permissions. Read permission
is required to query the NSG status or membership
roster. Execute permission is required to attach processes
or threads to an NSG.
Success. Failure. In this case, errno is set to indicate
If the nsg_init() function fails, it sets errno to one of
the following values for the specified condition: An NSG
already exists for the specified key, but the caller does
not have access based on the NSG's current permissions.
An NSG already exists for the specified key, but NSG_CREATE
and NSG_EXCL flags were specified. No NSG exists for
the specified key, and the NSG_CREATE flag was not specified.
No space exists for the new NSG specified by
NSG_CREATE. The NSG_GETBYPID flag was set and the process
identified by key was not found. One or more illegal values
for flags was set.
Functions: nsg_attach_pid(3), nsg_attach_thread(3),
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