| PERCPU(9) | Kernel Developer's Manual | PERCPU(9) |
percpu, percpu_alloc,
percpu_free, percpu_getref,
percpu_putref, percpu_foreach
—
#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);
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.
percpu_alloc(size)percpu_alloc() returns a handle for the per-CPU
storage.percpu_free(pc,
size)percpu_alloc(). When
percpu_free() returns, pc is
undefined. Treat this as an expensive operation.percpu_getref(pc)percpu_getref() in either thread or interrupt
context. Follow each percpu_getref() call with a
matching call to percpu_putref().percpu_putref(pc)percpu_getref(). Re-enables
preemption.percpu_foreach(pc,
cb, arg)(*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.percpu interface is implemented within the file
sys/kern/subr_percpu.c.
percpu interface first appeared in
NetBSD 6.0.
| May 31, 2017 | NetBSD 9.3 |