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Index: sys/kern/subr_blist.c
===================================================================
--- sys/kern/subr_blist.c
+++ sys/kern/subr_blist.c
@@ -130,9 +130,10 @@
/*
* static support functions
*/
-static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count);
-static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t cursor, daddr_t count,
- u_daddr_t radix);
+static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk,
+ int *count, int maxcount);
+static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t cursor, int *count,
+ int maxcount, u_daddr_t radix);
static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count,
u_daddr_t radix);
@@ -193,7 +194,6 @@
/*
* Use binary search, or a faster method, to find the 1 bit in a u_daddr_t.
- * Assumes that the argument has only one bit set.
*/
static inline int
bitpos(u_daddr_t mask)
@@ -210,7 +210,7 @@
hi = BLIST_BMAP_RADIX;
while (lo + 1 < hi) {
mid = (lo + hi) >> 1;
- if ((mask >> mid) != 0)
+ if ((mask & (((u_daddr_t)1 << mid) - 1)) == 0)
lo = mid;
else
hi = mid;
@@ -284,11 +284,13 @@
* 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 > maxcount)
+ panic("invalid parameters");
+ if (maxcount > BLIST_MAX_ALLOC)
panic("allocation too large");
/*
@@ -299,10 +301,10 @@
*/
for (;;) {
blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, count,
- bl->bl_radix);
+ maxcount, 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);
@@ -603,12 +605,11 @@
* common ancestor to mark any subtrees made completely empty.
*/
static int
-blst_next_leaf_alloc(blmeta_t *scan, daddr_t blk, int count)
+blst_next_leaf_alloc(blmeta_t *scan, daddr_t blk, int count, int maxcount)
{
blmeta_t *next;
- daddr_t skip;
u_daddr_t radix;
- int digit;
+ int avail, digit;
next = scan + 1;
blk += BLIST_BMAP_RADIX;
@@ -618,27 +619,32 @@
next++;
radix *= BLIST_META_RADIX;
}
- if (((next->bm_bitmap + 1) & ~((u_daddr_t)-1 << count)) != 0) {
- /*
- * The next leaf doesn't have enough free blocks at the
- * beginning to complete the spanning allocation.
- */
- return (ENOMEM);
+ avail = (~next->bm_bitmap != 0) ?
+ bitpos(~next->bm_bitmap) : BLIST_BMAP_RADIX;
+ if (avail < count) {
+ /*
+ * The next leaf doesn't have enough free blocks at the
+ * beginning to complete the spanning allocation.
+ */
+ return (0);
}
+ count = ummin(avail, maxcount);
/* Clear the first 'count' bits in the next leaf to allocate. */
next->bm_bitmap &= (u_daddr_t)-1 << count;
/*
* Update bitmaps of next-ancestors, up to least common ancestor.
*/
- skip = radix_to_skip(radix);
- while (radix != BLIST_BMAP_RADIX && next->bm_bitmap == 0) {
- (--next)->bm_bitmap ^= 1;
- radix /= BLIST_META_RADIX;
- }
- if (next->bm_bitmap == 0)
- scan[-digit * skip].bm_bitmap ^= (u_daddr_t)1 << digit;
- return (0);
+ while (next->bm_bitmap == 0) {
+ if (--next == scan) {
+ next[-digit * radix_to_skip(radix)].bm_bitmap ^=
+ (u_daddr_t)1 << digit;
+ break;
+ }
+ next->bm_bitmap ^= 1;
+ }
+
+ return (count);
}
/*
@@ -649,13 +655,13 @@
* crosses a leaf boundary.
*/
static daddr_t
-blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count)
+blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int *count, int maxcount)
{
u_daddr_t cursor_mask, mask;
int count1, hi, lo, num_shifts, range1, range_ext;
range1 = 0;
- count1 = count - 1;
+ count1 = *count - 1;
num_shifts = fls(count1);
mask = scan->bm_bitmap;
while ((-mask & ~mask) != 0 && num_shifts > 0) {
@@ -710,43 +716,52 @@
/*
* The least significant set bit in mask marks the start of the first
- * available range of sufficient size. Clear all the bits but that one,
- * and then find its position.
+ * available range of sufficient size. Find its position.
*/
- mask &= -mask;
lo = bitpos(mask);
- hi = lo + count;
- if (hi > BLIST_BMAP_RADIX) {
- /*
- * An allocation within this leaf is impossible, so a successful
- * allocation depends on the next leaf providing some of the blocks.
- */
- if (blst_next_leaf_alloc(scan, blk, hi - BLIST_BMAP_RADIX) != 0)
+ /*
+ * Find how much space is available starting at that position.
+ */
+ mask = ~(scan->bm_bitmap | bitrange(0, lo));
+ if (mask != 0) {
+ /* Count the 1 bits starting at position lo. */
+ hi = bitpos(mask);
+ if (lo + maxcount < hi)
+ hi = lo + maxcount;
+ *count = hi - lo;
+ } else if (lo + maxcount <= BLIST_BMAP_RADIX) {
+ /* All the blocks we can use are available here. */
+ hi = lo + maxcount;
+ *count = maxcount;
+ } else {
+ /* Check next leaf for some of the blocks we want or need. */
+ *count -= BLIST_BMAP_RADIX - lo;
+ maxcount -= BLIST_BMAP_RADIX - lo;
+ hi = blst_next_leaf_alloc(scan, blk, *count, maxcount);
+ if (hi < *count)
/*
- * The hint cannot be updated, because the same
- * allocation request could be satisfied later, by this
- * leaf, if the state of the next leaf changes, and
- * without any changes to this leaf.
+ * The next leaf cannot supply enough blocks to reach
+ * the minimum required allocation. The hint cannot be
+ * updated, because the same allocation request could
+ * be satisfied later, by this leaf, if the state of
+ * the next leaf changes, and without any changes to
+ * this leaf.
*/
return (SWAPBLK_NONE);
+ *count = BLIST_BMAP_RADIX - lo + hi;
hi = BLIST_BMAP_RADIX;
}
- /* Set the bits of mask at position 'lo' and higher. */
- mask = -mask;
if (hi == BLIST_BMAP_RADIX) {
/*
* Update bighint. There is no allocation bigger than range1
* available in this leaf after this allocation completes.
*/
scan->bm_bighint = range1;
- } else {
- /* Clear the bits of mask at position 'hi' and higher. */
- mask &= (u_daddr_t)-1 >> (BLIST_BMAP_RADIX - hi);
}
/* Clear the allocated bits from this leaf. */
- scan->bm_bitmap &= ~mask;
+ scan->bm_bitmap &= ~bitrange(lo, hi - lo);
return (blk + lo);
}
@@ -759,7 +774,8 @@
* and we have a few optimizations strewn in as well.
*/
static daddr_t
-blst_meta_alloc(blmeta_t *scan, daddr_t cursor, daddr_t count, u_daddr_t radix)
+blst_meta_alloc(blmeta_t *scan, daddr_t cursor, int *count,
+ int maxcount, u_daddr_t radix)
{
daddr_t blk, i, r, skip;
u_daddr_t bit, mask;
@@ -767,7 +783,7 @@
int digit;
if (radix == BLIST_BMAP_RADIX)
- return (blst_leaf_alloc(scan, cursor, count));
+ return (blst_leaf_alloc(scan, cursor, count, maxcount));
blk = cursor & -radix;
scan_from_start = (cursor == blk);
radix /= BLIST_META_RADIX;
@@ -797,12 +813,12 @@
bit = mask & -mask;
digit = bitpos(bit);
i = 1 + digit * skip;
- if (count <= scan[i].bm_bighint) {
+ if (*count <= scan[i].bm_bighint) {
/*
* The allocation might fit beginning in the i'th subtree.
*/
r = blst_meta_alloc(&scan[i], cursor + digit * radix,
- count, radix);
+ count, maxcount, radix);
if (r != SWAPBLK_NONE) {
if (scan[i].bm_bitmap == 0)
scan->bm_bitmap ^= bit;
@@ -818,7 +834,7 @@
*/
if (scan_from_start && !(digit == BLIST_META_RADIX - 1 &&
scan[i].bm_bighint == BLIST_MAX_ALLOC))
- scan->bm_bighint = count - 1;
+ scan->bm_bighint = *count - 1;
return (SWAPBLK_NONE);
}
@@ -1077,7 +1093,7 @@
for (;;) {
char buf[1024];
long long da = 0;
- long long count = 0;
+ int count = 0, maxcount = 0;
printf("%lld/%lld/%lld> ", (long long)blist_avail(bl),
(long long)size, (long long)bl->bl_radix);
@@ -1086,7 +1102,7 @@
break;
switch(buf[0]) {
case 'r':
- if (sscanf(buf + 1, "%lld", &count) == 1) {
+ if (sscanf(buf + 1, "%d", &count) == 1) {
blist_resize(&bl, count, 1, M_WAITOK);
} else {
printf("?\n");
@@ -1102,22 +1118,23 @@
sbuf_delete(s);
break;
case 'a':
- if (sscanf(buf + 1, "%lld", &count) == 1) {
- daddr_t blk = blist_alloc(bl, count);
- printf(" R=%08llx\n", (long long)blk);
+ if (sscanf(buf + 1, "%d%d", &count, &maxcount) == 2) {
+ daddr_t blk = blist_alloc(bl, &count, maxcount);
+ printf(" R=%08llx, c=%08d\n",
+ (long long)blk, count);
} else {
printf("?\n");
}
break;
case 'f':
- if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
+ if (sscanf(buf + 1, "%llx %d", &da, &count) == 2) {
blist_free(bl, da, count);
} else {
printf("?\n");
}
break;
case 'l':
- if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
+ if (sscanf(buf + 1, "%llx %d", &da, &count) == 2) {
printf(" n=%jd\n",
(intmax_t)blist_fill(bl, da, count));
} else {
@@ -1129,17 +1146,22 @@
puts(
"p -print\n"
"s -stats\n"
- "a %d -allocate\n"
+ "a %d %d -allocate\n"
"f %x %d -free\n"
"l %x %d -fill\n"
"r %d -resize\n"
- "h/? -help"
+ "h/? -help\n"
+ "q -quit"
);
break;
+ case 'q':
+ break;
default:
printf("?\n");
break;
}
+ if (buf[0] == 'q')
+ break;
}
return(0);
}
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 minpages);
/*
* 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 minpages)
{
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 (npages >= minpages) {
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);
sp = TAILQ_NEXT(sp, sw_list);
+ if (blk != SWAPBLK_NONE) {
+ *io_npages = npages;
+ blk += sp->sw_first;
+ sp->sw_used += npages;
+ swap_pager_avail -= npages;
+ swp_sizecheck();
+ swdevhd = sp;
+ break;
+ }
+ 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) {
+ 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, 2);
if (blk == SWAPBLK_NONE) {
for (j = 0; j < n; ++j)
rtvals[i+j] = VM_PAGER_FAIL;

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