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lgrp_latency_cookie(3lgrp) [opensolaris man page]

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)

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lgrp_init(3LGRP)														  lgrp_init(3LGRP)

NAME
lgrp_init - initialize lgroup interface SYNOPSIS
cc [ flag... ] file... -llgrp [ library... ] #include <sys/lgrp_user.h> lgrp_cookie_t lgrp_init(lgrp_view_t view); The lgrp_init() function initializes the lgroup interface and takes a snapshot of the lgroup hierarchy with the given view. If the given view is LGRP_VIEW_CALLER, the snapshot contains only the resources that are available to the caller (for example, with respect to processor sets). When the view is LGRP_VIEW_OS, the snapshot contains what is available to the operating system. Given the view, lgrp_init() returns a cookie representing this snapshot of the lgroup hierarchy. This cookie should be used with other rou- tines in the lgroup interface needing the lgroup hierarchy. The lgrp_fini(3LGRP) function should be called with the cookie when it is no longer needed. 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. 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. 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. 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. Upon successful completion, lgrp_init() returns a cookie. Otherwise it returns LGRP_COOKIE_NONE and sets errno to indicate the error. The lgrp_init() function will fail if: EINVAL The view is not valid. ENOMEM There was not enough memory to allocate the snapshot of the lgroup hierarchy. See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Evolving | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ lgrp_children(3LGRP), lgrp_cookie_stale(3LGRP), lgrp_cpus(3LGRP), lgrp_fini(3LGRP), lgrp_mem_size(3LGRP), lgrp_nlgrps(3LGRP), lgrp_par- ents(3LGRP), lgrp_resources(3LGRP), lgrp_root(3LGRP), lgrp_view(3LGRP), liblgrp(3LIB), attributes(5) 26 Jan 2005 lgrp_init(3LGRP)
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