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Index: sys/kern/subr_blist.c
===================================================================
--- sys/kern/subr_blist.c
+++ sys/kern/subr_blist.c
@@ -284,11 +284,11 @@
* not be allocated.
*/
daddr_t
-blist_alloc(blist_t bl, daddr_t count)
+blist_alloc(blist_t bl, int *count, int maxcount)
{
daddr_t blk;
- if (count > BLIST_MAX_ALLOC)
+ if (*count > BLIST_MAX_ALLOC)
panic("allocation too large");
/*
@@ -298,11 +298,11 @@
* stop further iterations.
*/
for (;;) {
- blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, count,
+ blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, *count,
bl->bl_radix);
if (blk != SWAPBLK_NONE) {
- bl->bl_avail -= count;
- bl->bl_cursor = blk + count;
+ bl->bl_avail -= *count;
+ bl->bl_cursor = blk + *count;
if (bl->bl_cursor == bl->bl_blocks)
bl->bl_cursor = 0;
return (blk);
Index: sys/sys/blist.h
===================================================================
--- sys/sys/blist.h
+++ sys/sys/blist.h
@@ -33,7 +33,7 @@
* Usage:
* blist = blist_create(blocks, flags)
* (void) blist_destroy(blist)
- * blkno = blist_alloc(blist, count)
+ * blkno = blist_alloc(blist, &count, maxcount)
* (void) blist_free(blist, blkno, count)
* nblks = blist_fill(blist, blkno, count)
* (void) blist_resize(&blist, count, freeextra, flags)
@@ -69,11 +69,11 @@
#define SWAPBLK_NONE ((daddr_t)((u_daddr_t)SWAPBLK_MASK + 1))/* flag */
/*
- * Both blmeta and bmu_bitmap MUST be a power of 2 in size.
+ * Both blmeta and bm_bitmap MUST be a power of 2 in size.
*/
typedef struct blmeta {
- u_daddr_t bm_bitmap; /* bitmap if we are a leaf */
+ u_daddr_t bm_bitmap; /* bitmap marking unfilled block sets*/
daddr_t bm_bighint; /* biggest contiguous block hint*/
} blmeta_t;
@@ -92,7 +92,7 @@
struct sbuf;
-daddr_t blist_alloc(blist_t blist, daddr_t count);
+daddr_t blist_alloc(blist_t blist, int *count, int maxcount);
daddr_t blist_avail(blist_t blist);
blist_t blist_create(daddr_t blocks, int flags);
void blist_destroy(blist_t blist);
Index: sys/vm/swap_pager.c
===================================================================
--- sys/vm/swap_pager.c
+++ sys/vm/swap_pager.c
@@ -407,7 +407,7 @@
* Swap bitmap functions
*/
static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages);
-static daddr_t swp_pager_getswapspace(int npages);
+static daddr_t swp_pager_getswapspace(int *npages, int limit);
/*
* Metadata functions
@@ -708,9 +708,10 @@
/*
* SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
*
- * Allocate swap for the requested number of pages. The starting
- * swap block number (a page index) is returned or SWAPBLK_NONE
- * if the allocation failed.
+ * Allocate swap for up to the requested number of pages, and at
+ * least a minimum number of pages. The starting swap block number
+ * (a page index) is returned or SWAPBLK_NONE if the allocation
+ * failed.
*
* Also has the side effect of advising that somebody made a mistake
* when they configured swap and didn't configure enough.
@@ -720,38 +721,49 @@
* We allocate in round-robin fashion from the configured devices.
*/
static daddr_t
-swp_pager_getswapspace(int npages)
+swp_pager_getswapspace(int *io_npages, int limit)
{
daddr_t blk;
struct swdevt *sp;
- int i;
+ int mpages, npages;
blk = SWAPBLK_NONE;
+ npages = mpages = *io_npages;
mtx_lock(&sw_dev_mtx);
+ if (TAILQ_EMPTY(&swtailq)) {
+ mtx_unlock(&sw_dev_mtx);
+ return (blk);
+ }
sp = swdevhd;
- for (i = 0; i < nswapdev; i++) {
+ while (mpages >= limit) {
if (sp == NULL)
sp = TAILQ_FIRST(&swtailq);
- if (!(sp->sw_flags & SW_CLOSING)) {
- blk = blist_alloc(sp->sw_blist, npages);
- if (blk != SWAPBLK_NONE) {
- blk += sp->sw_first;
- sp->sw_used += npages;
- swap_pager_avail -= npages;
- swp_sizecheck();
- swdevhd = TAILQ_NEXT(sp, sw_list);
- goto done;
- }
- }
+ if ((sp->sw_flags & SW_CLOSING) == 0)
+ blk = blist_alloc(sp->sw_blist, &npages, mpages);
+ if (blk != SWAPBLK_NONE)
+ break;
sp = TAILQ_NEXT(sp, sw_list);
+ if (swdevhd == sp) {
+ mpages = npages - 1;
+ npages >>= 1;
+ }
}
- if (swap_pager_full != 2) {
- printf("swap_pager_getswapspace(%d): failed\n", npages);
- swap_pager_full = 2;
- swap_pager_almost_full = 1;
+ if (blk != SWAPBLK_NONE) {
+ *io_npages = npages;
+ blk += sp->sw_first;
+ sp->sw_used += npages;
+ swap_pager_avail -= npages;
+ swp_sizecheck();
+ swdevhd = TAILQ_NEXT(sp, sw_list);
+ } else {
+ if (swap_pager_full != 2) {
+ printf("swp_pager_getswapspace(%d): failed\n",
+ *io_npages);
+ swap_pager_full = 2;
+ swap_pager_almost_full = 1;
+ }
+ swdevhd = NULL;
}
- swdevhd = NULL;
-done:
mtx_unlock(&sw_dev_mtx);
return (blk);
}
@@ -886,35 +898,30 @@
int
swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
{
- int n = 0;
- daddr_t blk = SWAPBLK_NONE;
+ int i, n;
+ daddr_t blk;
vm_pindex_t beg = start; /* save start index */
daddr_t addr, n_free, s_free;
swp_pager_init_freerange(&s_free, &n_free);
VM_OBJECT_WLOCK(object);
- while (size) {
- if (n == 0) {
- n = BLIST_MAX_ALLOC;
- while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
- n >>= 1;
- if (n == 0) {
- swp_pager_meta_free(object, beg, start - beg);
- VM_OBJECT_WUNLOCK(object);
- return (-1);
- }
- }
+ while (beg + size > start) {
+ n = min(BLIST_MAX_ALLOC, beg + size - start);
+ blk = swp_pager_getswapspace(&n, 1);
+ if (blk == SWAPBLK_NONE) {
+ swp_pager_meta_free(object, beg, start - beg);
+ VM_OBJECT_WUNLOCK(object);
+ return (-1);
}
- addr = swp_pager_meta_build(object, start, blk);
- if (addr != SWAPBLK_NONE)
+ for (i = 0; i < n; ++i) {
+ addr = swp_pager_meta_build(object, start + i, blk + i);
+ if (addr == SWAPBLK_NONE)
+ continue;
swp_pager_update_freerange(&s_free, &n_free, addr);
- --size;
- ++start;
- ++blk;
- --n;
+ }
+ start += n;
}
swp_pager_freeswapspace(s_free, n_free);
- swp_pager_meta_free(object, start, n);
VM_OBJECT_WUNLOCK(object);
return (0);
}
@@ -1384,18 +1391,8 @@
n = min(BLIST_MAX_ALLOC, count - i);
n = min(n, nsw_cluster_max);
- /*
- * Get biggest block of swap we can. If we fail, fall
- * back and try to allocate a smaller block. Don't go
- * overboard trying to allocate space if it would overly
- * fragment swap.
- */
- while (
- (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
- n > 4
- ) {
- n >>= 1;
- }
+ /* Get a block of swap of size up to size n. */
+ blk = swp_pager_getswapspace(&n, 4);
if (blk == SWAPBLK_NONE) {
for (j = 0; j < n; ++j)
rtvals[i+j] = VM_PAGER_FAIL;

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