SEQ_HLIST_NEXT_PERCP(9) The Linux VFS SEQ_HLIST_NEXT_PERCP(9)NAME
seq_hlist_next_percpu - move to the next position of the percpu hlist array
SYNOPSIS
struct hlist_node * seq_hlist_next_percpu(void * v, struct hlist_head __percpu * head, int * cpu, loff_t * pos);
ARGUMENTS
v
pointer to current hlist_node
head
pointer to percpu array of struct hlist_heads
cpu
pointer to cpu "cursor"
pos
start position of sequence
DESCRIPTION
Called at seq_file->op->next.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 SEQ_HLIST_NEXT_PERCP(9)
Check Out this Related Man Page
PERCPU(9) BSD Kernel Developer's Manual PERCPU(9)NAME
percpu, percpu_alloc, percpu_free, percpu_getref, percpu_putref, percpu_foreach -- per-CPU storage allocator
SYNOPSIS
#include <sys/percpu.h>
typedef void (*percpu_callback_t)(void *, void *, struct cpu_info *);
percpu_t *
percpu_alloc(size_t size);
void
percpu_free(percpu_t *pc, size_t size);
void *
percpu_getref(percpu_t *pc);
void
percpu_putref(percpu_t *pc);
void
percpu_foreach(percpu_t *pc, percpu_callback_t cb, void *arg);
DESCRIPTION
The machine-independent percpu interface provides per-CPU, CPU-local memory reservations to kernel subsystems. percpu_alloc(size) reserves
on each CPU an independent memory region of size bytes that is local to that CPU, returning a handle (percpu_t) to those regions. A thread
may subsequently ask for a pointer, p, to the region held by the percpu_t on the thread's current CPU. Until the thread relinquishes the
pointer, or voluntarily sleeps, the thread may read or write the region at p without causing interprocessor memory synchronization.
FUNCTIONS
percpu_alloc(size)
Call this in thread context to allocate size bytes of local storage on each CPU. The storage is initialized with zeroes. Treat
this as an expensive operation. percpu_alloc() returns NULL on failure, and a handle for the per-CPU storage on success.
percpu_free(pc, size)
Call this in thread context to return to the system the per-CPU storage held by pc. size should match the size passed to
percpu_alloc(). When percpu_free() returns, pc is undefined. Treat this as an expensive operation.
percpu_getref(pc)
Disable preemption and return a pointer to the storage held by pc on the local CPU. Use percpu_getref() in either thread or inter-
rupt context. Follow each percpu_getref() call with a matching call to percpu_putref().
percpu_putref(pc)
Indicate that the thread is finished with the pointer returned by the matching call to percpu_getref(). Re-enables preemption.
percpu_foreach(pc, cb, arg)
On each CPU, for ci the corresponding struct cpu_info * and p the CPU-local storage held by pc, run (*cb)(p, arg, ci). Call this in
thread context. cb should be non-blocking and fast. Do not rely on cb to be run on the CPUs in any particular order.
CODE REFERENCES
The percpu interface is implemented within the file sys/kern/subr_percpu.c.
SEE ALSO atomic_ops(3), kmem(9), pcq(9), pool_cache(9), xcall(9)HISTORY
The percpu interface first appeared in NetBSD 6.0.
AUTHORS
YAMAMOTO Takashi <yamt@NetBSD.org>
BSD January 23, 2010 BSD
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