'\" te
.\" Copyright (c) 2005, Sun Microsystems, Inc. All Rights Reserved.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
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.TH LGRP_INIT 3LGRP "Jan 26, 2005"
.SH NAME
lgrp_init \- initialize lgroup interface
.SH SYNOPSIS
.LP
.nf
cc [ \fIflag\fR... ] \fIfile\fR\&.\|.\|. \fB-llgrp\fR [ \fIlibrary\fR... ]
#include <sys/lgrp_user.h>

\fBlgrp_cookie_t\fR \fBlgrp_init\fR(\fBlgrp_view_t\fR \fIview\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBlgrp_init()\fR function initializes the lgroup interface and takes a
snapshot of the lgroup hierarchy with the given \fIview\fR.  If the given
\fIview\fR is \fBLGRP_VIEW_CALLER\fR, the snapshot contains only the resources
that are available to the caller (for example, with respect to processor sets).
When the \fIview\fR is \fBLGRP_VIEW_OS\fR, the snapshot contains what is
available to the operating system.
.sp
.LP
Given the \fIview\fR, \fBlgrp_init()\fR returns a cookie representing this
snapshot of the lgroup hierarchy. This cookie should be used with other
routines in the lgroup interface needing the lgroup hierarchy. The
\fBlgrp_fini\fR(3LGRP) function should be called with the cookie when it is no
longer needed.
.sp
.LP
The lgroup hiearchy represents the latency topology of the machine.  The
hierarchy is simplified to be a tree and can be used to find the nearest
resources.
.sp
.LP
The lgroup hiearchy consists of a root lgroup, which is the maximum  bounding
locality group of the system, contains all the CPU and memory resources of the
machine, and may contain  other locality groups that contain CPUs and memory
within a smaller locality. The leaf lgroups contain resources within the
smallest latency.
.sp
.LP
The resources of a given lgroup come directly from the lgroup itself or from
leaf lgroups contained within the lgroup. Leaf lgroups directly contain their
own resources and do not encapsulate any other lgroups.
.sp
.LP
The lgroup hierarchy can be used to find the nearest resources. From a given
lgroup, the closest resources can be found in the lgroup itself. After that,
the next nearest resources can be found in its parent lgroup, and so on until
the root lgroup is reached where all the resources of the machine are located.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBlgrp_init()\fR returns a cookie. Otherwise it
returns \fBLGRP_COOKIE_NONE\fR and sets \fBerrno\fR to indicate the error.
.SH ERRORS
.sp
.LP
The \fBlgrp_init()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The view is not valid.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 10n
There was not enough memory to allocate the snapshot of the lgroup hierarchy.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Evolving
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBlgrp_children\fR(3LGRP), \fBlgrp_cookie_stale\fR(3LGRP),
\fBlgrp_cpus\fR(3LGRP), \fBlgrp_fini\fR(3LGRP), \fBlgrp_mem_size\fR(3LGRP),
\fBlgrp_nlgrps\fR(3LGRP), \fBlgrp_parents\fR(3LGRP),
\fBlgrp_resources\fR(3LGRP), \fBlgrp_root\fR(3LGRP), \fBlgrp_view\fR(3LGRP),
\fBliblgrp\fR(3LIB), \fBattributes\fR(5)