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comments. related to PR/44969

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yamt 2011-07-26 13:09:11 +00:00
parent 9d109b3018
commit e2fcae61c5
1 changed files with 47 additions and 3 deletions
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50
sys/kern/subr_vmem.c
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@ -1,4 +1,4 @@
/* $NetBSD: subr_vmem.c,v 1.58 2010/12/17 22:24:11 yamt Exp $ */
/* $NetBSD: subr_vmem.c,v 1.59 2011/07/26 13:09:11 yamt Exp $ */
/*-
* Copyright (c)2006,2007,2008,2009 YAMAMOTO Takashi,
@ -38,7 +38,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_vmem.c,v 1.58 2010/12/17 22:24:11 yamt Exp $");
__KERNEL_RCSID(0, "$NetBSD: subr_vmem.c,v 1.59 2011/07/26 13:09:11 yamt Exp $");
#if defined(_KERNEL)
#include "opt_ddb.h"
@ -289,6 +289,15 @@ bt_freehead_tofree(vmem_t *vm, vmem_size_t size)
return &vm->vm_freelist[idx];
}
/*
* bt_freehead_toalloc: return the freelist for the given size and allocation
* strategy.
*
* for VM_INSTANTFIT, return the list in which any blocks are large enough
* for the requested size. otherwise, return the list which can have blocks
* large enough for the requested size.
*/
static struct vmem_freelist *
bt_freehead_toalloc(vmem_t *vm, vmem_size_t size, vm_flag_t strat)
{
@ -702,6 +711,9 @@ vmem_rehash(vmem_t *vm, size_t newhashsize, vm_flag_t flags)
/*
* vmem_fit: check if a bt can satisfy the given restrictions.
*
* it's a caller's responsibility to ensure the region is big enough
* before calling us.
*/
static vmem_addr_t
@ -711,7 +723,7 @@ vmem_fit(const bt_t *bt, vmem_size_t size, vmem_size_t align, vmem_size_t phase,
vmem_addr_t start;
vmem_addr_t end;
KASSERT(bt->bt_size >= size);
KASSERT(bt->bt_size >= size); /* caller's responsibility */
/*
* XXX assumption: vmem_addr_t and vmem_size_t are
@ -912,6 +924,10 @@ vmem_xalloc(vmem_t *vm, vmem_size_t size0, vmem_size_t align, vmem_size_t phase,
if (align == 0) {
align = vm->vm_quantum_mask + 1;
}
/*
* allocate boundary tags before acquiring the vmem lock.
*/
btnew = bt_alloc(vm, flags);
if (btnew == NULL) {
return VMEM_ADDR_NULL;
@ -922,6 +938,9 @@ vmem_xalloc(vmem_t *vm, vmem_size_t size0, vmem_size_t align, vmem_size_t phase,
return VMEM_ADDR_NULL;
}
/*
* choose a free block from which we allocate.
*/
retry_strat:
first = bt_freehead_toalloc(vm, size, strat);
end = &vm->vm_freelist[VMEM_MAXORDER];
@ -930,6 +949,13 @@ retry:
VMEM_LOCK(vm);
vmem_check(vm);
if (strat == VM_INSTANTFIT) {
/*
* just choose the first block which satisfies our restrictions.
*
* note that we don't need to check the size of the blocks
* because any blocks found on these list should be larger than
* the given size.
*/
for (list = first; list < end; list++) {
bt = LIST_FIRST(list);
if (bt != NULL) {
@ -938,9 +964,27 @@ retry:
if (start != VMEM_ADDR_NULL) {
goto gotit;
}
/*
* don't bother to follow the bt_freelist link
* here. the list can be very long and we are
* told to run fast. blocks from the later free
* lists are larger and have better chances to
* satisfy our restrictions.
*/
}
}
} else { /* VM_BESTFIT */
/*
* we assume that, for space efficiency, it's better to
* allocate from a smaller block. thus we will start searching
* from the lower-order list than VM_INSTANTFIT.
* however, don't bother to find the smallest block in a free
* list because the list can be very long. we can revisit it
* if/when it turns out to be a problem.
*
* note that the 'first' list can contain blocks smaller than
* the requested size. thus we need to check bt_size.
*/
for (list = first; list < end; list++) {
LIST_FOREACH(bt, list, bt_freelist) {
if (bt->bt_size >= size) {