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Simplify vmspace initialization. The bcopy() of fields from the old

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vmspace to the new vmspace in vmspace_exec() is mostly wasted effort.  With
one exception, vm_swrss, the copied fields are immediately overwritten.
Instead, initialize these fields to zero in vmspace_alloc(), eliminating a
bcopy() from vmspace_exec() and a bzero() from vmspace_fork().
This commit is contained in:
alc 2004-07-24 07:40:35 +00:00
parent 1df6bf2b92
commit 2057234305
2 changed files with 8 additions and 14 deletions
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19
sys/vm/vm_map.c
View File

@ -244,7 +244,6 @@ vm_map_zdtor(void *mem, int size, void *arg)
/*
* Allocate a vmspace structure, including a vm_map and pmap,
* and initialize those structures. The refcnt is set to 1.
* The remaining fields must be initialized by the caller.
*/
struct vmspace *
vmspace_alloc(min, max)
@ -258,6 +257,13 @@ vmspace_alloc(min, max)
vm->vm_map.pmap = vmspace_pmap(vm); /* XXX */
vm->vm_refcnt = 1;
vm->vm_shm = NULL;
vm->vm_swrss = 0;
vm->vm_tsize = 0;
vm->vm_dsize = 0;
vm->vm_ssize = 0;
vm->vm_taddr = 0;
vm->vm_daddr = 0;
vm->vm_maxsaddr = 0;
vm->vm_exitingcnt = 0;
return (vm);
}
@ -2391,13 +2397,6 @@ vmspace_fork(struct vmspace *vm1)
old_map->infork = 1;
vm2 = vmspace_alloc(old_map->min_offset, old_map->max_offset);
/*
* Using vm_{start,end}copy is invalid for more fields than
* it is valid here. For the most part, initialize size
* fields to zero and update them as map entries are copied
*/
bzero(&vm2->vm_startcopy,
(caddr_t)&vm2->vm_endcopy - (caddr_t)&vm2->vm_startcopy);
vm2->vm_taddr = vm1->vm_taddr;
vm2->vm_daddr = vm1->vm_daddr;
vm2->vm_maxsaddr = vm1->vm_maxsaddr;
@ -2829,9 +2828,7 @@ vmspace_exec(struct proc *p, vm_offset_t minuser, vm_offset_t maxuser)
GIANT_REQUIRED;
newvmspace = vmspace_alloc(minuser, maxuser);
bcopy(&oldvmspace->vm_startcopy, &newvmspace->vm_startcopy,
(caddr_t) &newvmspace->vm_endcopy -
(caddr_t) &newvmspace->vm_startcopy);
newvmspace->vm_swrss = oldvmspace->vm_swrss;
/*
* This code is written like this for prototype purposes. The
* goal is to avoid running down the vmspace here, but let the

3
sys/vm/vm_map.h
View File

@ -221,8 +221,6 @@ struct vmspace {
struct vm_map vm_map; /* VM address map */
struct pmap vm_pmap; /* private physical map */
struct shmmap_state *vm_shm; /* SYS5 shared memory private data XXX */
/* we copy between vm_startcopy and vm_endcopy on fork */
#define vm_startcopy vm_swrss
segsz_t vm_swrss; /* resident set size before last swap */
segsz_t vm_tsize; /* text size (pages) XXX */
segsz_t vm_dsize; /* data size (pages) XXX */
@ -230,7 +228,6 @@ struct vmspace {
caddr_t vm_taddr; /* (c) user virtual address of text */
caddr_t vm_daddr; /* (c) user virtual address of data */
caddr_t vm_maxsaddr; /* user VA at max stack growth */
#define vm_endcopy vm_exitingcnt
int vm_exitingcnt; /* several processes zombied in exit1 */
int vm_refcnt; /* number of references */
};