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Index: head/sys/kern/subr_blist.c
===================================================================
--- head/sys/kern/subr_blist.c
+++ head/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);
@@ -293,12 +294,14 @@
* 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;
- KASSERT(count <= BLIST_MAX_ALLOC,
- ("allocation too large: %d", (int)count));
+ 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
@@ -306,19 +309,18 @@
* non-zero. When the cursor is zero, an allocation failure will
* stop further iterations.
*/
- cursor = bl->bl_cursor;
- for (;;) {
- blk = blst_meta_alloc(bl->bl_root, cursor, count,
+ for (cursor = bl->bl_cursor;; cursor = 0) {
+ 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);
- } else if (cursor == 0)
+ }
+ if (cursor == 0)
return (SWAPBLK_NONE);
- cursor = 0;
}
}
@@ -615,29 +617,34 @@
* 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;
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 = imin(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.
@@ -650,7 +657,7 @@
}
next->bm_bitmap ^= 1;
}
- return (0);
+ return (count);
}
/*
@@ -674,13 +681,13 @@
* 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 (flip_hibits(mask) != 0 && num_shifts > 0) {
@@ -735,40 +742,50 @@
/*
* 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 (flip_hibits(mask) != 0) {
+ /* Count the 1 bits starting at position lo. */
+ hi = bitpos(flip_hibits(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;
@@ -784,7 +801,8 @@
* 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 mask;
@@ -792,7 +810,7 @@
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;
@@ -821,12 +839,12 @@
do {
digit = bitpos(mask);
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 ^= bitrange(digit, 1);
@@ -842,7 +860,7 @@
*/
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);
}
@@ -1101,7 +1119,7 @@
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);
@@ -1110,7 +1128,7 @@
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");
@@ -1126,22 +1144,23 @@
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 {
@@ -1153,7 +1172,7 @@
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"
Index: head/sys/sys/blist.h
===================================================================
--- head/sys/sys/blist.h
+++ head/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)
@@ -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: head/sys/vm/swap_pager.c
===================================================================
--- head/sys/vm/swap_pager.c
+++ head/sys/vm/swap_pager.c
@@ -725,23 +725,24 @@
{
daddr_t blk;
struct swdevt *sp;
- int npages;
+ int mpages, npages;
blk = SWAPBLK_NONE;
- npages = *io_npages;
+ npages = mpages = *io_npages;
mtx_lock(&sw_dev_mtx);
sp = swdevhd;
while (!TAILQ_EMPTY(&swtailq)) {
if (sp == NULL)
sp = TAILQ_FIRST(&swtailq);
if ((sp->sw_flags & SW_CLOSING) == 0)
- blk = blist_alloc(sp->sw_blist, npages);
+ 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;
}
}

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