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 snap‐
shot 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 plat‐
forms.
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 ALSOlgrp_init(3LGRP), lgrp_parents(3LGRP), lgrp_children(3LGRP),
liblgrp(3LIB), attributes(5)SunOS 5.10 26 Jan 2005 lgrp_latency(3LGRP)
