lgrp_latency(3LGRP)					 Locality Group Library Functions				       lgrp_latency(3LGRP)

NAME

       lgrp_latency, lgrp_latency_cookie - get latency between two lgroups

SYNOPSIS

       cc [ flag... ] file... -llgrp [ library... ]
       #include <sys/lgrp_user.h>

       int lgrp_latency_cookie(lgrp_cookie_t cookie, lgrp_id_t from,
	    lgrp_id_t to, lgrp_lat_between_t between);

       int lgrp_latency(lgrp_id_t from, lgrp_id_t to);

DESCRIPTION

       The  lgrp_latency_cookie()  function  takes  a  cookie  representing  a snapshot of the lgroup hierarchy obtained from lgrp_init(3LGRP) and
       returns the latency value between a hardware resource in the from lgroup to a hardware resource in the to  lgroup.  If  from  is  the  same
       lgroup as to, the latency value within that lgroup is returned.

       The between argument should be set to the following value to specify between which hardware resources the latency should be measured:

	 LGRP_LAT_CPU_TO_MEM	 /* latency from CPU to memory */

       The  latency  value  is defined by the operating system and is platform-specific. It can be used only for relative comparison of lgroups on
       the running system. It does not necessarily represent the actual latency between hardware devices, and it might not  be	applicable  across
       platforms.

       The  lgrp_latency()  function  is  similiar to the lgrp_latency_cookie() function, but returns the latency between the given lgroups at the
       given instant in time. Since lgroups can be freed and reallocated, this function might not be able to provide a	consistent  answer  across
       calls. For that reason, the lgrp_latency_cookie() function should be used in its place.

RETURN VALUES

       Upon successful completion, the latency value is returned. Otherwise -1 is returned and errno is set to indicate the error.

ERRORS

       The lgrp_latency_cookie() and lgrp_latency() functions will fail if:

       EINVAL	 The specified cookie, lgroup ID, or value given for the between argument is not valid.

       ESRCH	 The specified lgroup ID was not found, the from lgroup does not contain any CPUs, or the to lgroup does not have any memory.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       lgrp_init(3LGRP), lgrp_parents(3LGRP), lgrp_children(3LGRP), liblgrp(3LIB), attributes(5)

SunOS 5.11							    26 Jan 2005 					       lgrp_latency(3LGRP)