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nsg_init(3)
NAME
  nsg_init - Look up or create a NUMA Scheduling Group (libnuma library)

SYNOPSIS
  #include <numa.h>


  nsgid_t nsg_init(
	  key_t key,
	  ulong_t flags );

PARAMETERS
  key 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

  flags
      Specifies lookup or creation flags. See DESCRIPTION for details.

DESCRIPTION
  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.

  If the flags parameter includes the NSG_GETBYPID flag, 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 requested NSG. If the NSG identified by key does not already
  exist, an error will be returned unless the NSG_CREATE flag is specified.

  The NSG_CREATE flag instructs nsg_init() to create 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 the NSG_GETBYPID flag is set and the process identified by the value of
  key does not exist, an error is returned.  If the NSG_CREATE flag is set
  along with the NSG_GETBYPID flag, 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.


  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.

  If NSG_CLEANUP is specified in flags, the NSG will be marked for automatic
  deletion when the nsg_perm.nattach member of the associated nsgid_ds
  structure transitions from non-zero to zero.

RETURN VALUES
  NSG identifier of the NUMA Scheduling Group
      Success.

  -1  Failure. In this case, errno is set to indicate the error.

ERRORS
  If the nsg_init() function fails, it sets errno to one of the following
  values for the specified condition:

  [EACCES]
      An NSG already exists for the specified key, but the caller does not
      have access based on the NSG's current permissions.

  [EEXIST]
      An NSG already exists for the specified key, but NSG_CREATE and
      NSG_EXCL flags were specified.

  [ENOENT]
      No NSG exists for the specified key, and the NSG_CREATE flag was not
      specified.

  [ESRCH]
      The NSG_GETBYPID flag was set and the process identified by key was not
      found.

  [EINVAL]
      One or more illegal values for flags was set.







SEE ALSO
  Functions: nsg_attach_pid(3), nsg_attach_thread(3), numa_intro(3)


  Files: numa_types(4)

Index for Section 3

Alphabetical listing for N

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