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Index: kern/subr_blist.c
===================================================================
--- kern/subr_blist.c
+++ kern/subr_blist.c
@@ -74,12 +74,11 @@
* allocated.
*
* NOTE: the allocator cannot currently allocate more than
- * BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too
- * large' if you try. This is an area that could use improvement. The
- * radix is large enough that this restriction does not effect the swap
- * system, though. Currently only the allocation code is affected by
- * this algorithmic unfeature. The freeing code can handle arbitrary
- * ranges.
+ * BLIST_BMAP_RADIX blocks per call. This is an area that could use
+ * improvement. The radix is large enough that this restriction does
+ * not effect the swap system, though. Currently only the allocation
+ * code is affected by this algorithmic unfeature. The freeing code
+ * can handle arbitrary ranges.
*
* This code can be compiled stand-alone for debugging.
*/
@@ -119,20 +118,21 @@
#define bitcount64(x) __bitcount64((uint64_t)(x))
#define malloc(a,b,c) calloc(a, 1)
#define free(a,b) free(a)
+#define min(a,b) ((a) < (b) ? (a) : (b))
#define ummin(a,b) ((a) < (b) ? (a) : (b))
+#define KASSERT(a,b)
#include <sys/blist.h>
-void panic(const char *ctl, ...);
-
#endif
/*
* 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);
@@ -192,8 +192,7 @@
/*
- * 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.
+ * Find the first bit set in a u_daddr_t.
*/
static inline int
bitpos(u_daddr_t mask)
@@ -205,15 +204,19 @@
case sizeof(long long):
return (ffsll(mask) - 1);
#endif
+#ifdef HAVE_INLINE_FFS
+ case sizeof(int):
+ return (ffs(mask) - 1);
+#endif
default:
lo = 0;
hi = BLIST_BMAP_RADIX;
while (lo + 1 < hi) {
mid = (lo + hi) >> 1;
- if ((mask >> mid) != 0)
+ if (mask & bitrange(0, mid))
+ hi = mid;
+ else
lo = mid;
- else
- hi = mid;
}
return (lo);
}
@@ -235,8 +238,7 @@
blist_t bl;
u_daddr_t nodes, radix;
- if (blocks == 0)
- panic("invalid block count");
+ KASSERT(blocks > 0, ("invalid block count"));
/*
* Calculate the radix and node count used for scanning.
@@ -284,12 +286,14 @@
* 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, cursor;
- if (count > BLIST_MAX_ALLOC)
- panic("allocation too large");
+ KASSERT(*count <= maxcount,
+ ("invalid parameters %d > %d", *count, maxcount));
+ KASSERT(maxcount <= BLIST_MAX_ALLOC,
+ ("allocation too large: %d", maxcount));
/*
* This loop iterates at most twice. An allocation failure in the
@@ -299,11 +303,11 @@
*/
cursor = bl->bl_cursor;
for (;;) {
- blk = blst_meta_alloc(bl->bl_root, cursor, count,
+ blk = blst_meta_alloc(bl->bl_root, cursor, count, 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);
@@ -325,15 +329,15 @@
/*
* blist_free() - free up space in the block bitmap. Return the base
- * of a contiguous region. Panic if an inconsistancy is
- * found.
+ * of a contiguous region.
*/
void
blist_free(blist_t bl, daddr_t blkno, daddr_t count)
{
- if (blkno < 0 || blkno + count > bl->bl_blocks)
- panic("freeing invalid range");
+ KASSERT(blkno >= 0 && blkno + count <= bl->bl_blocks,
+ ("freeing invalid range: blkno %llx, count %d, blocks %lld",
+ (long long)blkno, (int)count, (long long)bl->bl_blocks));
blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix);
bl->bl_avail += count;
}
@@ -349,8 +353,9 @@
{
daddr_t filled;
- if (blkno < 0 || blkno + count > bl->bl_blocks)
- panic("filling invalid range");
+ KASSERT(blkno >= 0 && blkno + count <= bl->bl_blocks,
+ ("filling invalid range: blkno %llx, count %d, blocks %lld",
+ (long long)blkno, (int)count, (long long)bl->bl_blocks));
filled = blst_meta_fill(bl->bl_root, blkno, count, bl->bl_radix);
bl->bl_avail -= filled;
return (filled);
@@ -604,42 +609,48 @@
* 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;
radix = BLIST_BMAP_RADIX;
- while ((digit = ((blk / radix) & BLIST_META_MASK)) == 0 &&
- (next->bm_bitmap & 1) == 1) {
+ while ((next->bm_bitmap & 1) == 1 &&
+ (digit = ((blk / radix) & BLIST_META_MASK)) == 0) {
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);
+ if ((next->bm_bitmap & 1) != 1)
+ return (0);
+ 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 = min(avail, maxcount);
/* Clear the first 'count' bits in the next leaf to allocate. */
- next->bm_bitmap &= (u_daddr_t)-1 << count;
+ next->bm_bitmap &= ~bitrange(0, 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) {
+ scan[-digit * radix_to_skip(radix)].bm_bitmap ^=
+ (u_daddr_t)1 << digit;
+ break;
+ }
+ next->bm_bitmap ^= 1;
+ }
+
+ return (count);
}
/*
@@ -650,13 +661,13 @@
* 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) {
@@ -711,40 +722,50 @@
/*
* 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.
+ */
+ if ((-mask & ~mask) != 0) {
+ /* Count the 1 bits starting at position lo. */
+ hi = bitpos(-mask & ~mask) + count1;
+ if (maxcount < hi - lo)
+ hi = lo + maxcount;
+ *count = hi - lo;
+ mask = bitrange(lo, *count);
+ } else if (maxcount <= BLIST_BMAP_RADIX - lo) {
+ /* All the blocks we can use are available here. */
+ hi = lo + maxcount;
+ *count = maxcount;
+ mask = bitrange(lo, *count);
+ } else {
+ /* Check next leaf for some of the blocks we want or need. */
+ count1 = *count - (BLIST_BMAP_RADIX - lo);
+ maxcount -= BLIST_BMAP_RADIX - lo;
+ hi = blst_next_leaf_alloc(scan, blk, count1, maxcount);
+ if (hi < count1)
/*
- * 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;
@@ -760,7 +781,8 @@
* 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;
@@ -768,7 +790,7 @@
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;
@@ -798,12 +820,12 @@
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;
@@ -819,7 +841,7 @@
*/
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);
}
@@ -840,8 +862,9 @@
* count n
*/
mask = bitrange(blk & BLIST_BMAP_MASK, count);
- if (scan->bm_bitmap & mask)
- panic("freeing free block");
+ KASSERT((scan->bm_bitmap & mask) == 0,
+ ("freeing free block: %llx, size %d, mask %llx",
+ (long long)blk, count, (long long)scan->bm_bitmap & mask));
scan->bm_bitmap |= mask;
}
@@ -1078,7 +1101,7 @@
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);
@@ -1087,7 +1110,7 @@
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");
@@ -1103,22 +1126,23 @@
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 {
@@ -1130,31 +1154,24 @@
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);
+ return (0);
}
-void
-panic(const char *ctl, ...)
-{
- va_list va;
-
- va_start(va, ctl);
- vfprintf(stderr, ctl, va);
- fprintf(stderr, "\n");
- va_end(va);
- exit(1);
-}
-
#endif
Index: sys/blist.h
===================================================================
--- sys/blist.h
+++ 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: vm/swap_pager.c
===================================================================
--- vm/swap_pager.c
+++ 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 +721,47 @@
* 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);
sp = swdevhd;
- for (i = 0; i < nswapdev; i++) {
+ while (!TAILQ_EMPTY(&swtailq)) {
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) {
+ if (npages <= limit)
+ break;
+ mpages = npages - 1;
+ npages >>= 1;
}
- sp = TAILQ_NEXT(sp, sw_list);
}
- 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 +896,28 @@
int
swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
{
- int n = 0;
- daddr_t blk = SWAPBLK_NONE;
- vm_pindex_t beg = start; /* save start index */
- daddr_t addr, n_free, s_free;
+ daddr_t addr, blk, n_free, s_free;
+ int i, j, n;
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);
- }
- }
+ for (i = 0; i < size; i += n) {
+ n = min(BLIST_MAX_ALLOC, size - i);
+ blk = swp_pager_getswapspace(&n, 1);
+ if (blk == SWAPBLK_NONE) {
+ swp_pager_meta_free(object, start, i);
+ VM_OBJECT_WUNLOCK(object);
+ return (-1);
}
- addr = swp_pager_meta_build(object, start, blk);
- if (addr != SWAPBLK_NONE)
- swp_pager_update_freerange(&s_free, &n_free, addr);
- --size;
- ++start;
- ++blk;
- --n;
+ for (j = 0; j < n; ++j) {
+ addr = swp_pager_meta_build(object,
+ start + i + j, blk + j);
+ if (addr != SWAPBLK_NONE)
+ swp_pager_update_freerange(&s_free, &n_free,
+ addr);
+ }
}
swp_pager_freeswapspace(s_free, n_free);
- swp_pager_meta_free(object, start, n);
VM_OBJECT_WUNLOCK(object);
return (0);
}
@@ -1384,18 +1387,8 @@
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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