lgrpplat.c revision c39996a7c853f35e9cf2fc40b30e0d2eec0e9996
/*
* CDDL HEADER START
*
* 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.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include <sys/machsystm.h>
#include <sys/pci_cfgspace.h>
#include <sys/pci_impl.h>
#include <vm/seg_kmem.h>
/*
* lgroup platform support for x86 platforms.
*/
#define MAX_NODES 8
/*
* Multiprocessor Opteron machines have Non Uniform Memory Access (NUMA).
*
* Until System Affinity Resource Table (SRAT) becomes part of ACPI standard,
* we need to examine registers in PCI configuration space to determine how
* many nodes are in the system and which CPUs and memory are in each node.
* This could be determined by probing all memory from each CPU, but that is
* too expensive to do while booting the kernel.
*
* NOTE: Using these PCI configuration space registers to determine this
* locality info is Opteron K8 specific and not guaranteed to work on
* the next generation Opteron processor. Furthermore, we assume that
* there is one CPU per node and CPU 0 is in node 0, CPU 1 is in node 1,
* etc. which should be true for Opteron K8....
*/
/*
* Opteron DRAM Address Map in PCI configuration space gives base and limit
* of physical memory in each node for Opteron K8. The following constants
* and macros define their contents, structure, and access.
*/
/*
* How many bits to shift Opteron DRAM Address Map base and limit registers
* to get actual value
*/
/*
* Bit masks defining what's in Opteron DRAM Address Map base register
*/
/*
* Macros to get values from Opteron DRAM Address Map base register
*/
#define OPT_DRAMBASE(reg) \
/*
* Bit masks defining what's in Opteron DRAM Address Map limit register
*/
/*
* Macros to get values from Opteron DRAM Address Map limit register
*/
#define OPT_DRAMLIMIT(reg) \
/*
* Opteron Node ID register in PCI configuration space contains
* number of nodes in system, etc. for Opteron K8. The following
* constants and macros define its contents, structure, and access.
*/
/*
* Bit masks defining what's in Opteron Node ID register
*/
/*
* How many bits in Opteron Node ID register to shift right to get actual value
*/
/*
* Macros to get values from Opteron Node ID register
*/
#define OPT_NODE_CNT(reg) \
/*
* PCI configuration space registers accessed by specifying
* a bus, device, function, and offset. The following constants
* define the values needed to access Opteron K8 configuration
* info to determine its node topology
*/
#define OPT_PCS_BUS_CONFIG 0 /* Hypertransport config space bus */
/*
* Opteron PCI configuration space register function values
*/
#define OPT_PCS_FUNC_HT 0 /* Hypertransport configuration */
/*
* PCI Configuration Space register offsets
*/
/*
* Opteron PCI Configuration Space device IDs for nodes
*/
/*
* Bookkeeping for latencies seen during probing (used for verification)
*/
typedef struct lgrp_plat_latency_acct {
int la_count; /* occurrences */
/*
* Choices for probing to determine lgroup topology
*/
typedef enum lgrp_plat_probe_op {
LGRP_PLAT_PROBE_PGCPY, /* Use page copy */
LGRP_PLAT_PROBE_VENDOR /* Read vendor ID on Northbridge */
/*
* Opteron DRAM address map gives base and limit for physical memory in a node
*/
typedef struct opt_dram_addr_map {
/*
* Starting and ending page for physical memory in node
*/
typedef struct phys_addr_map {
int exists;
/*
* Opteron DRAM address map for each node
*/
/*
* Node ID register contents for each node
*/
/*
* Whether memory is interleaved across nodes causing MPO to be disabled
*/
int lgrp_plat_mem_intrlv = 0;
/*
* Number of nodes in system
*/
/*
* Physical address range for memory in each node
*/
/*
* Probe costs (individual and total) and flush cost
*/
/*
* Error code for latency adjustment and verification
*/
int lgrp_plat_probe_error_code = 0;
/*
* How much latencies were off from minimum values gotten
*/
/*
* Unique probe latencies and number of occurrences of each
*/
/*
* Size of memory buffer in each node for probing
*/
/*
* Virtual address of page in each node for probing
*/
/*
* Number of unique latencies in probe times
*/
int lgrp_plat_probe_nlatencies = 0;
/*
* How many rounds of probing to do
*/
/*
* Number of samples to take when probing each node
*/
/*
* Number of times to read vendor ID from Northbridge for each probe.
*/
/*
* How to probe to determine lgroup topology
*/
/*
* PFN of page in each node for probing
*/
/*
* Whether probe time was suspect (ie. not within tolerance of value that it
* should match)
*/
/*
* How long it takes to access memory from each node
*/
/*
* Min and max node memory probe times seen
*/
/*
* Allocate lgrp and lgrp stat arrays statically.
*/
static int nlgrps_alloc;
#define CPUID_FAMILY_OPTERON 15
uint_t opt_family = 0;
/*
* Determine whether we're running on an AMD Opteron K8 machine
*/
int
is_opteron(void)
{
if (x86_vendor != X86_VENDOR_AMD)
return (0);
return (1);
else
return (0);
}
int
{
if (max_mem_nodes == 1)
return (0);
return ((int)hand);
}
{
if (max_mem_nodes == 1)
return (LGRP_DEFAULT_HANDLE);
return ((lgrp_handle_t)mnode);
}
int
{
int node;
if (max_mem_nodes == 1)
return (0);
/*
* Skip nodes with no memory
*/
continue;
return (node);
}
return (-1);
}
/*
* Configure memory nodes for machines with more than one node (ie NUMA)
*/
void
{
/*
* Boot install lists are arranged <addr, len>, ...
*/
while (list) {
int node;
continue;
}
/*
* When there is only one memnode, just add memory to memnode
*/
if (max_mem_nodes == 1) {
continue;
}
/*
* mem_node_add_slice() expects to get a memory range that
* is within one memnode, so need to split any memory range
* that spans multiple memnodes into subranges that are each
* contained within one memnode when feeding them to
* mem_node_add_slice()
*/
do {
/*
* Panic if DRAM address map registers or SRAT say
* memory in node doesn't exist or address from
* boot installed memory list entry isn't in this node.
* This shouldn't happen and rest of code can't deal
* with this if it does.
*/
"to add installed memory address 0x%lx\n",
}
/*
* End of current subrange should not span memnodes
*/
/*
* Next subrange starts after end of current one
*/
}
mem_node_physalign = 0;
mem_node_pfn_shift = 0;
}
/*
* Platform-specific initialization of lgroups
*/
void
lgrp_plat_init(void)
{
extern lgrp_load_t lgrp_expand_proc_thresh;
extern lgrp_load_t lgrp_expand_proc_diff;
/*
* Initialize as a UMA machine if this isn't an Opteron
*/
return;
}
/*
* Read configuration registers from PCI configuration space to
* determine node information, which memory is in each node, etc.
*
* Write to PCI configuration space address register to specify
*/
/*
* Read node ID register for node 0 to get node count
*/
/*
* Read node ID register (except for node 0 which we just read)
*/
if (node > 0) {
}
/*
* Read DRAM base and limit registers which specify
* physical memory range of each node
*/
/*
* Increment device number to next node and register offset for
* DRAM base register of next node
*/
off += 4;
dev++;
/*
* Both read and write enable bits must be enabled in DRAM
* address map base register for physical memory to exist in
* node
*/
/*
* Mark node memory as non-existent and set start and
* end addresses to be same in lgrp_plat_node_memory[]
*/
continue;
}
/*
* Get PFN for first page in each node,
* so we can probe memory to determine latency topology
*/
/*
* Mark node memory as existing and remember physical address
* range of each node for use later
*/
}
/*
* Only use one memory node if memory is interleaved between any nodes
*/
if (lgrp_plat_mem_intrlv) {
(void) lgrp_topo_ht_limit_set(1);
} else {
/*
* Probing errors can mess up the lgroup topology and force us
* fall back to a 2 level lgroup topology. Here we bound how
* tall the lgroup topology can grow in hopes of avoiding any
* anamolies in probing from messing up the lgroup topology
* by limiting the accuracy of the latency topology.
*
* Assume that nodes will at least be configured in a ring,
* so limit height of lgroup topology to be less than number
* of nodes on a system with 4 or more nodes
*/
if (lgrp_plat_node_cnt >= 4 &&
}
/*
* Lgroups on Opteron architectures have but a single physical
* processor. Tune lgrp_expand_proc_thresh and lgrp_expand_proc_diff
* so that lgrp_choose() will spread things out aggressively.
*/
}
/*
* Latencies must be within 1/(2**LGRP_LAT_TOLERANCE_SHIFT) of each other to
* be considered same
*/
#define LGRP_LAT_TOLERANCE_SHIFT 4
/*
* Adjust latencies between nodes to be symmetric, normalize latencies between
* any nodes that are within some tolerance to be same, and make local
* latencies be same
*/
static void
lgrp_plat_latency_adjust(void)
{
int i;
int j;
int k;
int l;
u_longlong_t t;
/*
* Nothing to do when this is an UMA machine
*/
if (max_mem_nodes == 1)
return;
/*
* Make sure that latencies are symmetric between any two nodes
* (ie. latency(node0, node1) == latency(node1, node0))
*/
for (i = 0; i < lgrp_plat_node_cnt; i++)
for (j = 0; j < lgrp_plat_node_cnt; j++) {
t1 = lgrp_plat_probe_times[i][j];
t2 = lgrp_plat_probe_times[j][i];
continue;
/*
* Latencies should be same
* - Use minimum of two latencies which should be same
* - Track suspect probe times not within tolerance of
* min value
* - Remember how much values are corrected by
*/
t = t2;
lgrp_plat_probe_suspect[i][j]++;
lgrp_plat_probe_suspect[j][i]++;
}
t = t1;
lgrp_plat_probe_suspect[i][j]++;
lgrp_plat_probe_suspect[j][i]++;
}
}
lgrp_plat_probe_times[i][j] =
lgrp_plat_probe_times[j][i] = t;
}
/*
* Keep track of which latencies get corrected
*/
for (i = 0; i < MAX_NODES; i++)
for (j = 0; j < MAX_NODES; j++)
lat_corrected[i][j] = 0;
/*
* For every two nodes, see whether there is another pair of nodes which
* are about the same distance apart and make the latencies be the same
* if they are close enough together
*/
for (i = 0; i < lgrp_plat_node_cnt; i++)
for (j = 0; j < lgrp_plat_node_cnt; j++) {
/*
* Pick one pair of nodes (i, j)
* and get latency between them
*/
t1 = lgrp_plat_probe_times[i][j];
/*
* Skip this pair of nodes if there isn't a latency
* for it yet
*/
if (t1 == 0)
continue;
for (k = 0; k < lgrp_plat_node_cnt; k++)
for (l = 0; l < lgrp_plat_node_cnt; l++) {
/*
* Pick another pair of nodes (k, l)
* not same as (i, j) and get latency
* between them
*/
if (k == i && l == j)
continue;
t2 = lgrp_plat_probe_times[k][l];
/*
* Skip this pair of nodes if there
* isn't a latency for it yet
*/
if (t2 == 0)
continue;
/*
* Skip nodes (k, l) if they already
* have same latency as (i, j) or
* their latency isn't close enough to
* be considered/made the same
*/
t1 >> lgrp_plat_probe_lt_shift) ||
continue;
/*
* Make latency(i, j) same as
* latency(k, l), try to use latency
* that has been adjusted already to get
* more consistency (if possible), and
* remember which latencies were
* adjusted for next time
*/
if (lat_corrected[i][j]) {
t = t1;
t2 = t;
} else if (lat_corrected[k][l]) {
t = t2;
t1 = t;
} else {
t = t2;
else
t = t1;
}
lgrp_plat_probe_times[i][j] =
lgrp_plat_probe_times[k][l] = t;
lat_corrected[i][j] =
lat_corrected[k][l] = 1;
}
}
/*
* Local latencies should be same
* - Find min and max local latencies
* - Make all local latencies be minimum
*/
min = -1;
max = 0;
for (i = 0; i < lgrp_plat_node_cnt; i++) {
t = lgrp_plat_probe_times[i][i];
if (t == 0)
continue;
min = t;
if (t > max)
max = t;
}
for (i = 0; i < lgrp_plat_node_cnt; i++) {
int local;
local = lgrp_plat_probe_times[i][i];
if (local == 0)
continue;
/*
* Track suspect probe times that aren't within
* tolerance of minimum local latency and how much
* probe times are corrected by
*/
lgrp_plat_probe_suspect[i][i]++;
/*
* Make local latencies be minimum
*/
lgrp_plat_probe_times[i][i] = min;
}
}
/*
* Determine max probe time again since just adjusted latencies
*/
for (i = 0; i < lgrp_plat_node_cnt; i++)
for (j = 0; j < lgrp_plat_node_cnt; j++) {
t = lgrp_plat_probe_times[i][j];
if (t > lgrp_plat_probe_time_max)
}
}
/*
* Verify following about latencies between nodes:
*
* - Latencies should be symmetric (ie. latency(a, b) == latency(b, a))
* - Local latencies same
* - Local < remote
* - Number of latencies seen is reasonable
* - Number of occurrences of a given latency should be more than 1
*
* Returns:
* 0 Success
* -1 Not symmetric
* -2 Local latencies not same
* -3 Local >= remote
* -4 Wrong number of latencies
* -5 Not enough occurrences of given latency
*/
static int
lgrp_plat_latency_verify(void)
{
int i;
int j;
int probed;
/*
* Nothing to do when this is an UMA machine, lgroup topology is
* limited to 2 levels, or there aren't any probe times yet
*/
return (0);
/*
* Make sure that latencies are symmetric between any two nodes
* (ie. latency(node0, node1) == latency(node1, node0))
*/
for (i = 0; i < lgrp_plat_node_cnt; i++)
for (j = 0; j < lgrp_plat_node_cnt; j++) {
t1 = lgrp_plat_probe_times[i][j];
t2 = lgrp_plat_probe_times[j][i];
continue;
return (-1);
}
/*
* Local latencies should be same
*/
t1 = lgrp_plat_probe_times[0][0];
for (i = 1; i < lgrp_plat_node_cnt; i++) {
t2 = lgrp_plat_probe_times[i][i];
if (t2 == 0)
continue;
if (t1 == 0) {
continue;
}
return (-2);
}
/*
* Local latencies should be less than remote
*/
if (t1) {
for (i = 0; i < lgrp_plat_node_cnt; i++)
for (j = 0; j < lgrp_plat_node_cnt; j++) {
t2 = lgrp_plat_probe_times[i][j];
if (i == j || t2 == 0)
continue;
return (-3);
}
}
/*
* Rest of checks are not very useful for machines with less than
* 4 nodes (which means less than 3 latencies on Opteron)
*/
if (lgrp_plat_node_cnt < 4)
return (0);
/*
* Need to see whether done probing in order to verify number of
* latencies are correct
*/
probed = 0;
for (i = 0; i < lgrp_plat_node_cnt; i++)
if (lgrp_plat_probe_times[i][i])
probed++;
if (probed != lgrp_plat_node_cnt)
return (0);
/*
* Determine number of unique latencies seen in probe times,
* their values, and number of occurrences of each
*/
MAX_NODES * sizeof (lgrp_plat_latency_acct_t));
for (i = 0; i < lgrp_plat_node_cnt; i++) {
for (j = 0; j < lgrp_plat_node_cnt; j++) {
int k;
/*
* Look at each probe time
*/
t1 = lgrp_plat_probe_times[i][j];
if (t1 == 0)
continue;
/*
* Account for unique latencies
*/
for (k = 0; k < lgrp_plat_node_cnt; k++) {
l = &lgrp_plat_probe_lat_acct[k];
/*
* Increment number of occurrences
* if seen before
*/
l->la_count++;
break;
} else if (l->la_value == 0) {
/*
* Record latency if haven't seen before
*/
l->la_count++;
break;
}
}
}
}
/*
* Number of latencies should be relative to number of
* nodes in system:
* - Same as nodes when nodes <= 2
* - Less than nodes when nodes > 2
* - Greater than 2 when nodes >= 4
*/
if ((lgrp_plat_node_cnt <= 2 &&
(lgrp_plat_node_cnt > 2 &&
lgrp_plat_probe_nlatencies <= 2))
return (-4);
/*
* There should be more than one occurrence of every latency
* as long as probing is complete
*/
for (i = 0; i < lgrp_plat_probe_nlatencies; i++) {
l = &lgrp_plat_probe_lat_acct[i];
if (l->la_count <= 1)
return (-5);
}
return (0);
}
/*
* Set lgroup latencies for 2 level lgroup topology
*/
static void
lgrp_plat_2level_setup(void)
{
int i;
if (lgrp_plat_node_cnt >= 4)
"MPO only optimizing for local and remote\n");
for (i = 0; i < lgrp_plat_node_cnt; i++) {
int j;
for (j = 0; j < lgrp_plat_node_cnt; j++) {
if (i == j)
lgrp_plat_probe_times[i][j] = 2;
else
lgrp_plat_probe_times[i][j] = 3;
}
}
}
/*
* Return time needed to probe from current CPU to memory in given node
*/
static hrtime_t
lgrp_plat_probe_time(int to)
{
/* LINTED: set but not used in function */
volatile uint_t dev_vendor;
int from;
int i;
int ipl;
int cnt;
extern int use_sse_pagecopy;
/*
* Determine ID of node containing current CPU
*/
/*
* Do common work for probing main memory
*/
if (lgrp_plat_probe_op == LGRP_PLAT_PROBE_PGCPY) {
/*
* Skip probing any nodes without memory and
* set probe time to 0
*/
return (0);
}
/*
* Invalidate caches once instead of once every sample
* which should cut cost of probing by a lot
*/
}
/*
* Probe from current CPU to given memory using specified operation
* and take specified number of samples
*/
max = 0;
min = -1;
for (i = 0; i < lgrp_plat_probe_nsamples; i++) {
/*
* Can't measure probe time if gethrtime() isn't working yet
*/
if (lgrp_plat_probe_cost == 0 && gethrtime() == 0)
return (0);
switch (lgrp_plat_probe_op) {
case LGRP_PLAT_PROBE_PGCPY:
default:
/*
* Measure how long it takes to copy page
* on top of itself
*/
if (use_sse_pagecopy)
else
break;
case LGRP_PLAT_PROBE_VENDOR:
/*
* Measure how long it takes to read vendor ID from
* Northbridge
*/
break;
}
}
/*
* Update minimum and maximum probe times between
* these two nodes
*/
return (min);
}
/*
* Probe memory in each node from current CPU to determine latency topology
*/
void
lgrp_plat_probe(void)
{
int from;
int i;
int to;
return;
/*
* Determine ID of node containing current CPU
*/
/*
* Don't need to probe if got times already
*/
return;
/*
* Read vendor ID in Northbridge or read and write page(s)
* in each node from current CPU and remember how long it takes,
* so we can build latency topology of machine later.
* This should approximate the memory latency between each node.
*/
for (i = 0; i < lgrp_plat_probe_nrounds; i++)
/*
* Get probe time and bail out if can't get it yet
*/
if (probe_time == 0)
return;
/*
* Keep lowest probe time as latency between nodes
*/
/*
* Update overall minimum and maximum probe times
* across all nodes
*/
if (probe_time < lgrp_plat_probe_time_min ||
lgrp_plat_probe_time_min == -1)
}
/*
* - Fix up latencies such that local latencies are same,
* latency(i, j) == latency(j, i), etc. (if possible)
*
* - Verify that latencies look ok
*
* - Fallback to just optimizing for local and remote if
* latencies didn't look right
*/
}
/*
* Platform-specific initialization
*/
void
lgrp_plat_main_init(void)
{
int curnode;
int ht_limit;
int i;
/*
* Print a notice that MPO is disabled when memory is interleaved
* across nodes....Would do this when it is discovered, but can't
* because it happens way too early during boot....
*/
if (lgrp_plat_mem_intrlv)
"MPO disabled because memory is interleaved\n");
/*
* Don't bother to do any probing if there is only one node or the
* height of the lgroup topology less than or equal to 2
*/
/*
* Setup lgroup latencies for 2 level lgroup topology
* (ie. local and remote only) if they haven't been set yet
*/
lgrp_plat_probe_time_max == 0)
return;
}
if (lgrp_plat_probe_op == LGRP_PLAT_PROBE_VENDOR) {
/*
* Should have been able to probe from CPU 0 when it was added
* to lgroup hierarchy, but may not have been able to then
* because it happens so early in boot that gethrtime() hasn't
* been initialized. (:-(
*/
return;
}
/*
* When probing memory, use one page for every sample to determine
* lgroup topology and taking multiple samples
*/
if (lgrp_plat_probe_memsize == 0)
/*
* Map memory in each node needed for probing to determine latency
* topology
*/
for (i = 0; i < lgrp_plat_node_cnt; i++) {
int mnode;
/*
* Skip this node and leave its probe page NULL
* if it doesn't have any memory
*/
lgrp_plat_probe_memory[i] = NULL;
continue;
}
/*
* Allocate one kernel virtual page
*/
if (lgrp_plat_probe_memory[i] == NULL) {
"lgrp_plat_main_init: couldn't allocate memory");
return;
}
/*
* Map virtual page to first page in node
*/
}
/*
* Probe from current CPU
*/
}
/*
* Allocate additional space for an lgroup.
*/
/* ARGSUSED */
lgrp_t *
{
return (NULL);
return (lgrp);
}
/*
* Platform handling for (re)configuration changes
*/
/* ARGSUSED */
void
{
}
/*
* Return the platform handle for the lgroup containing the given CPU
*/
/* ARGSUSED */
{
if (lgrp_plat_node_cnt == 1)
return (LGRP_DEFAULT_HANDLE);
}
/*
* Return the platform handle of the lgroup that contains the physical memory
* corresponding to the given page frame number
*/
/* ARGSUSED */
{
int mnode;
if (max_mem_nodes == 1)
return (LGRP_DEFAULT_HANDLE);
return (LGRP_NULL_HANDLE);
if (mnode < 0)
return (LGRP_NULL_HANDLE);
return (MEM_NODE_2_LGRPHAND(mnode));
}
/*
* Return the maximum number of lgrps supported by the platform.
* Before lgrp topology is known it returns an estimate based on the number of
* nodes. Once topology is known it returns the actual maximim number of lgrps
* created. Since x86 doesn't support dynamic addition of new nodes, this number
* may not grow during system lifetime.
*/
int
{
return (lgrp_topo_initialized ?
lgrp_alloc_max + 1 :
}
/*
* Return the number of free, allocatable, or installed
* pages in an lgroup
* This is a copy of the MAX_MEM_NODES == 1 version of the routine
* used when MPO is disabled (i.e. single lgroup) or this is the root lgroup
*/
/* ARGSUSED */
static pgcnt_t
{
extern struct memlist *phys_avail;
extern struct memlist *phys_install;
switch (query) {
case LGRP_MEM_SIZE_FREE:
case LGRP_MEM_SIZE_AVAIL:
return (npgs);
case LGRP_MEM_SIZE_INSTALL:
return (npgs);
default:
return ((pgcnt_t)0);
}
}
/*
* Return the number of free pages in an lgroup.
*
* For query of LGRP_MEM_SIZE_FREE, return the number of base pagesize
* pages on freelists. For query of LGRP_MEM_SIZE_AVAIL, return the
* number of allocatable base pagesize pages corresponding to the
* lgroup (e.g. do not include page_t's, BOP_ALLOC()'ed memory, ..)
* For query of LGRP_MEM_SIZE_INSTALL, return the amount of physical
* memory installed, regardless of whether or not it's usable.
*/
{
int mnode;
extern struct memlist *phys_avail;
extern struct memlist *phys_install;
if (plathand == LGRP_DEFAULT_HANDLE)
if (plathand != LGRP_NULL_HANDLE) {
switch (query) {
case LGRP_MEM_SIZE_FREE:
break;
case LGRP_MEM_SIZE_AVAIL:
break;
case LGRP_MEM_SIZE_INSTALL:
break;
default:
break;
}
}
}
return (npgs);
}
/*
* Return latency between "from" and "to" lgroups
*
* This latency number can only be used for relative comparison
* between lgroups on the running system, cannot be used across platforms,
* and may not reflect the actual latency. It is platform and implementation
* specific, so platform gets to decide its value. It would be nice if the
* number was at least proportional to make comparisons more meaningful though.
*/
/* ARGSUSED */
int
{
if (max_mem_nodes == 1)
return (0);
/*
* Return max latency for root lgroup
*/
return (lgrp_plat_probe_time_max);
/*
* Return 0 for nodes (lgroup platform handles) out of range
*/
return (0);
/*
* Probe from current CPU if its lgroup latencies haven't been set yet
* and we are trying to get latency from current CPU to some node
*/
}
/*
* Return platform handle for root lgroup
*/
lgrp_plat_root_hand(void)
{
return (LGRP_DEFAULT_HANDLE);
}