include/linux/topology.h

Source file repositories/reference/linux-study-clean/include/linux/topology.h

File Facts

System
Linux kernel
Corpus path
include/linux/topology.h
Extension
.h
Size
10144 bytes
Lines
355
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _LINUX_TOPOLOGY_H
#define _LINUX_TOPOLOGY_H

#include <linux/arch_topology.h>
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/bitops.h>
#include <linux/mmzone.h>
#include <linux/smp.h>
#include <linux/percpu.h>
#include <asm/topology.h>

#ifndef nr_cpus_node
#define nr_cpus_node(node) cpumask_weight(cpumask_of_node(node))
#endif

int arch_update_cpu_topology(void);

/* Conform to ACPI 2.0 SLIT distance definitions */
#define LOCAL_DISTANCE		10
#define REMOTE_DISTANCE		20
#define DISTANCE_BITS           8
#ifndef node_distance
#define node_distance(from,to)	((from) == (to) ? LOCAL_DISTANCE : REMOTE_DISTANCE)
#endif
#ifndef RECLAIM_DISTANCE
/*
 * If the distance between nodes in a system is larger than RECLAIM_DISTANCE
 * (in whatever arch specific measurement units returned by node_distance())
 * and node_reclaim_mode is enabled then the VM will only call node_reclaim()
 * on nodes within this distance.
 */
#define RECLAIM_DISTANCE 30
#endif

/*
 * The following tunable allows platforms to override the default node
 * reclaim distance (RECLAIM_DISTANCE) if remote memory accesses are
 * sufficiently fast that the default value actually hurts
 * performance.
 *
 * AMD EPYC machines use this because even though the 2-hop distance
 * is 32 (3.2x slower than a local memory access) performance actually
 * *improves* if allowed to reclaim memory and load balance tasks
 * between NUMA nodes 2-hops apart.
 */
extern int __read_mostly node_reclaim_distance;

#ifndef PENALTY_FOR_NODE_WITH_CPUS
#define PENALTY_FOR_NODE_WITH_CPUS	(1)
#endif

#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DECLARE_PER_CPU(int, numa_node);

#ifndef numa_node_id
/* Returns the number of the current Node. */
static inline int numa_node_id(void)
{
	return raw_cpu_read(numa_node);
}
#endif

#ifndef cpu_to_node
static inline int cpu_to_node(int cpu)
{
	return per_cpu(numa_node, cpu);
}
#endif

#ifndef set_numa_node
static inline void set_numa_node(int node)
{
	this_cpu_write(numa_node, node);
}
#endif

#ifndef set_cpu_numa_node
static inline void set_cpu_numa_node(int cpu, int node)
{
	per_cpu(numa_node, cpu) = node;
}
#endif

#else	/* !CONFIG_USE_PERCPU_NUMA_NODE_ID */

/* Returns the number of the current Node. */
#ifndef numa_node_id
static inline int numa_node_id(void)
{

Annotation

Implementation Notes