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Index: head/sys/vm/vm_reserv.c
===================================================================
--- head/sys/vm/vm_reserv.c
+++ head/sys/vm/vm_reserv.c
@@ -1030,56 +1030,49 @@
static void
vm_reserv_break(vm_reserv_t rv)
{
- int begin_zeroes, hi, i, lo;
+ u_long changes;
+ int bitpos, hi, i, lo;
vm_reserv_assert_locked(rv);
CTR5(KTR_VM, "%s: rv %p object %p popcnt %d inpartpop %d",
__FUNCTION__, rv, rv->object, rv->popcnt, rv->inpartpopq);
vm_reserv_remove(rv);
rv->pages->psind = 0;
- i = hi = 0;
- do {
- /* Find the next 0 bit. Any previous 0 bits are < "hi". */
- lo = ffsl(~(((1UL << hi) - 1) | rv->popmap[i]));
- if (lo == 0) {
- /* Redundantly clears bits < "hi". */
+ hi = lo = -1;
+ for (i = 0; i <= NPOPMAP; i++) {
+ /*
+ * "changes" is a bitmask that marks where a new sequence of
+ * 0s or 1s begins in popmap[i], with last bit in popmap[i-1]
+ * considered to be 1 if and only if lo == hi. The bits of
+ * popmap[-1] and popmap[NPOPMAP] are considered all 1s.
+ */
+ if (i == NPOPMAP)
+ changes = lo != hi;
+ else {
+ changes = rv->popmap[i];
+ changes ^= (changes << 1) | (lo == hi);
rv->popmap[i] = 0;
- rv->popcnt -= NBPOPMAP - hi;
- while (++i < NPOPMAP) {
- lo = ffsl(~rv->popmap[i]);
- if (lo == 0) {
- rv->popmap[i] = 0;
- rv->popcnt -= NBPOPMAP;
- } else
- break;
+ }
+ while (changes != 0) {
+ /*
+ * If the next change marked begins a run of 0s, set
+ * lo to mark that position. Otherwise set hi and
+ * free pages from lo up to hi.
+ */
+ bitpos = ffsl(changes) - 1;
+ changes ^= 1UL << bitpos;
+ if (lo == hi)
+ lo = NBPOPMAP * i + bitpos;
+ else {
+ hi = NBPOPMAP * i + bitpos;
+ vm_domain_free_lock(VM_DOMAIN(rv->domain));
+ vm_phys_free_contig(&rv->pages[lo], hi - lo);
+ vm_domain_free_unlock(VM_DOMAIN(rv->domain));
+ lo = hi;
}
- if (i == NPOPMAP)
- break;
- hi = 0;
}
- KASSERT(lo > 0, ("vm_reserv_break: lo is %d", lo));
- /* Convert from ffsl() to ordinary bit numbering. */
- lo--;
- if (lo > 0) {
- /* Redundantly clears bits < "hi". */
- rv->popmap[i] &= ~((1UL << lo) - 1);
- rv->popcnt -= lo - hi;
- }
- begin_zeroes = NBPOPMAP * i + lo;
- /* Find the next 1 bit. */
- do
- hi = ffsl(rv->popmap[i]);
- while (hi == 0 && ++i < NPOPMAP);
- if (i != NPOPMAP)
- /* Convert from ffsl() to ordinary bit numbering. */
- hi--;
- vm_domain_free_lock(VM_DOMAIN(rv->domain));
- vm_phys_free_contig(&rv->pages[begin_zeroes], NBPOPMAP * i +
- hi - begin_zeroes);
- vm_domain_free_unlock(VM_DOMAIN(rv->domain));
- } while (i < NPOPMAP);
- KASSERT(rv->popcnt == 0,
- ("vm_reserv_break: reserv %p's popcnt is corrupted", rv));
+ }
+ rv->popcnt = 0;
counter_u64_add(vm_reserv_broken, 1);
}

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