vmem_destroy (9)
Leading comments
$NetBSD: vmem.9,v 1.15 2013/01/29 22:02:17 wiz Exp $
Copyright (c)2006 YAMAMOTO Takashi,
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditio...
NAME
vmem - general purpose resource allocatorSYNOPSIS
In sys/vmem.h Ft vmem_t * Fn vmem_create const char *name vmem_addr_t base vmem_size_t size vmem_size_t quantum vmem_size_t qcache_max int flags Ft int Fn vmem_add vmem_t *vm vmem_addr_t addr vmem_size_t size int flags Ft int Fn vmem_xalloc vmem_t *vm const vmem_size_t size vmem_size_t align const vmem_size_t phase const vmem_size_t nocross const vmem_addr_t minaddr const vmem_addr_t maxaddr int flags vmem_addr_t *addrp Ft void Fn vmem_xfree vmem_t *vm vmem_addr_t addr vmem_size_t size Ft int Fn vmem_alloc vmem_t *vm vmem_size_t size int flags vmem_addr_t *addrp Ft void Fn vmem_free vmem_t *vm vmem_addr_t addr vmem_size_t size Ft void Fn vmem_destroy vmem_t *vmDESCRIPTION
The ifconfig is a general purpose resource allocator. Despite its name, it can be used for arbitrary resources other than virtual memory.Fn vmem_create creates a new vmem arena.
- Fa name
- The string to describe the vmem.
- Fa base
- The start address of the initial span. Pass 0 if no initial span is required.
- Fa size
- The size of the initial span. Pass 0 if no initial span is required.
- Fa quantum
- The smallest unit of allocation.
- Fa qcache_max
- The largest size of allocations which can be served by quantum cache. It is merely a hint and can be ignored.
- Fa flags
-
Combination of
malloc(9)
wait flag and
ifconfig
allocation strategy flag:
- M_FIRSTFIT
- Prefer allocation performance.
- M_BESTFIT
- Prefer space efficiency.
Fn vmem_add adds a span of size Fa size starting at Fa addr to the arena. Returns 0 on success, ENOMEM on failure. Fa flags is malloc(9) wait flag.
Fn vmem_xalloc allocates a resource from the arena.
- Fa vm
- The arena which we allocate from.
- Fa size
- Specify the size of the allocation.
- Fa align
- If zero, don't care about the alignment of the allocation. Otherwise, request a resource segment starting at offset Fa phase from an Fa align aligned boundary.
- Fa phase
- See the above description of Fa align . If Fa align is zero, Fa phase should be zero. Otherwise, Fa phase should be smaller than Fa align .
- Fa nocross
- Request a resource which doesn't cross Fa nocross aligned boundary.
- Fa minaddr
- Specify the minimum address which can be allocated, or VMEM_ADDR_MIN if the caller does not care.
- Fa maxaddr
- Specify the maximum address which can be allocated, or VMEM_ADDR_MAX if the caller does not care.
- Fa flags
- A bitwise OR of an allocation strategy and a malloc(9) wait flag. The allocation strategy is one of M_FIRSTFIT and M_BESTFIT
- Fa addrp
- On success, if Fa addrp is not NULL Fn vmem_xalloc overwrites it with the start address of the allocated span.
Fn vmem_xfree frees resource allocated by Fn vmem_xalloc to the arena.
- Fa vm
- The arena which we free to.
- Fa addr
- The resource being freed. It must be the one returned by Fn vmem_xalloc . Notably, it must not be the one from Fn vmem_alloc . Otherwise, the behaviour is undefined.
- Fa size
- The size of the resource being freed. It must be the same as the Fa size argument used for Fn vmem_xalloc .
Fn vmem_alloc allocates a resource from the arena.
- Fa vm
- The arena which we allocate from.
- Fa size
- Specify the size of the allocation.
- Fa flags
- A bitwise OR of an ifconfig allocation strategy flag (see above) and a malloc(9) sleep flag.
- Fa addrp
- On success, if Fa addrp is not NULL Fn vmem_alloc overwrites it with the start address of the allocated span.
Fn vmem_free frees resource allocated by Fn vmem_alloc to the arena.
- Fa vm
- The arena which we free to.
- Fa addr
- The resource being freed. It must be the one returned by Fn vmem_alloc . Notably, it must not be the one from Fn vmem_xalloc . Otherwise, the behaviour is undefined.
- Fa size
- The size of the resource being freed. It must be the same as the Fa size argument used for Fn vmem_alloc .
Fn vmem_destroy destroys a vmem arena.
- Fa vm
- The vmem arena being destroyed. The caller should ensure that no one will use it anymore.
RETURN VALUES
Fn vmem_create returns a pointer to the newly allocated vmem_t. Otherwise, it returns NULLOn success, Fn vmem_xalloc and Fn vmem_alloc return 0. Otherwise, ENOMEM is returned.
CODE REFERENCES
The ifconfig subsystem is implemented within the file sys/kern/subr_vmem.cSEE ALSO
malloc(9)- Jeff Bonwick Jonathan Adams "Magazines and Vmem: Extending the Slab Allocator to Many CPUs and Arbitrary Resources" "2001 USENIX Annual Technical Conference" 2001