vm_phys_enqueue_contig: handle npages==0
By letting vm_phys_enqueue_contig handle the case when npages == 0, the callers can stop checking it, and the compiler can stop zero-checking with every call to ffs(). Letting vm_phys_enqueue_contig call vm_phys_enqueue_contig for part of its work also saves a few bytes. The amd64 object code shrinks by 80 bytes. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D41154
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@ -72,6 +72,8 @@ __FBSDID("$FreeBSD$");
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_Static_assert(sizeof(long) * NBBY >= VM_PHYSSEG_MAX,
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"Too many physsegs.");
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_Static_assert(sizeof(long long) >= sizeof(vm_paddr_t),
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"vm_paddr_t too big for ffsll, flsll.");
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#ifdef NUMA
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struct mem_affinity __read_mostly *mem_affinity;
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@ -690,18 +692,16 @@ vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl, int order,
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*
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* The physical page m's buddy must not be free.
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*/
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static void
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static vm_page_t
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vm_phys_enq_range(vm_page_t m, u_int npages, struct vm_freelist *fl, int tail)
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{
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u_int n;
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int order;
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KASSERT(npages > 0, ("vm_phys_enq_range: npages is 0"));
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KASSERT(((VM_PAGE_TO_PHYS(m) + npages * PAGE_SIZE) &
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((PAGE_SIZE << (fls(npages) - 1)) - 1)) == 0,
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("vm_phys_enq_range: page %p and npages %u are misaligned",
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m, npages));
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do {
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while (npages > 0) {
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KASSERT(m->order == VM_NFREEORDER,
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("vm_phys_enq_range: page %p has unexpected order %d",
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m, m->order));
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@ -709,10 +709,10 @@ vm_phys_enq_range(vm_page_t m, u_int npages, struct vm_freelist *fl, int tail)
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KASSERT(order < VM_NFREEORDER,
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("vm_phys_enq_range: order %d is out of range", order));
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vm_freelist_add(fl, m, order, tail);
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n = 1 << order;
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m += n;
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npages -= n;
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} while (npages > 0);
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m += 1 << order;
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npages -= 1 << order;
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}
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return (m);
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}
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/*
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@ -744,7 +744,7 @@ vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
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{
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struct vm_freelist *alt, *fl;
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vm_page_t m;
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int avail, end, flind, freelist, i, need, oind, pind;
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int avail, end, flind, freelist, i, oind, pind;
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KASSERT(domain >= 0 && domain < vm_ndomains,
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("vm_phys_alloc_npages: domain %d is out of range", domain));
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@ -762,20 +762,18 @@ vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
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for (oind = 0; oind < VM_NFREEORDER; oind++) {
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while ((m = TAILQ_FIRST(&fl[oind].pl)) != NULL) {
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vm_freelist_rem(fl, m, oind);
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avail = 1 << oind;
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need = imin(npages - i, avail);
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for (end = i + need; i < end;)
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avail = i + (1 << oind);
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end = imin(npages, avail);
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while (i < end)
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ma[i++] = m++;
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if (need < avail) {
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if (i == npages) {
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/*
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* Return excess pages to fl. Its
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* order [0, oind) queues are empty.
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* Return excess pages to fl. Its order
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* [0, oind) queues are empty.
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*/
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vm_phys_enq_range(m, avail - need, fl,
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1);
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return (npages);
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} else if (i == npages)
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vm_phys_enq_range(m, avail - i, fl, 1);
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return (npages);
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}
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}
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}
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for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
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@ -785,21 +783,20 @@ vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
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NULL) {
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vm_freelist_rem(alt, m, oind);
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vm_phys_set_pool(pool, m, oind);
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avail = 1 << oind;
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need = imin(npages - i, avail);
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for (end = i + need; i < end;)
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avail = i + (1 << oind);
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end = imin(npages, avail);
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while (i < end)
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ma[i++] = m++;
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if (need < avail) {
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if (i == npages) {
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/*
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* Return excess pages to fl.
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* Its order [0, oind) queues
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* are empty.
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*/
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vm_phys_enq_range(m, avail -
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need, fl, 1);
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return (npages);
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} else if (i == npages)
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vm_phys_enq_range(m, avail - i,
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fl, 1);
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return (npages);
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}
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}
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}
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}
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@ -1146,7 +1143,7 @@ max_order(vm_page_t m)
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* because the size of a physical address exceeds the size of
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* a long.
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*/
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return (min(ffsl(VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT) - 1,
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return (min(ffsll(VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT) - 1,
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VM_NFREEORDER - 1));
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}
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@ -1162,6 +1159,7 @@ vm_phys_enqueue_contig(vm_page_t m, u_long npages)
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struct vm_freelist *fl;
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struct vm_phys_seg *seg;
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vm_page_t m_end;
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vm_paddr_t diff, lo;
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int order;
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/*
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@ -1173,15 +1171,15 @@ vm_phys_enqueue_contig(vm_page_t m, u_long npages)
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fl = (*seg->free_queues)[m->pool];
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m_end = m + npages;
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/* Free blocks of increasing size. */
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while ((order = max_order(m)) < VM_NFREEORDER - 1 &&
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m + (1 << order) <= m_end) {
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KASSERT(seg == &vm_phys_segs[m->segind],
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("%s: page range [%p,%p) spans multiple segments",
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__func__, m_end - npages, m));
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vm_freelist_add(fl, m, order, 1);
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m += 1 << order;
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lo = VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT;
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if (m < m_end &&
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(diff = lo ^ (lo + npages - 1)) != 0) {
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order = min(flsll(diff) - 1, VM_NFREEORDER - 1);
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m = vm_phys_enq_range(m, roundup2(-lo, 1 << order), fl, 1);
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}
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/* Free blocks of maximum size. */
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order = VM_NFREEORDER - 1;
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while (m + (1 << order) <= m_end) {
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KASSERT(seg == &vm_phys_segs[m->segind],
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("%s: page range [%p,%p) spans multiple segments",
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@ -1560,10 +1558,8 @@ vm_phys_alloc_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
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vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, oind);
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}
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/* Return excess pages to the free lists. */
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if (&m_run[npages] < m) {
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fl = (*queues)[VM_FREEPOOL_DEFAULT];
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vm_phys_enq_range(&m_run[npages], m - &m_run[npages], fl, 0);
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}
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fl = (*queues)[VM_FREEPOOL_DEFAULT];
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vm_phys_enq_range(&m_run[npages], m - &m_run[npages], fl, 0);
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return (m_run);
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}
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