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vm_phys: avoid waste in multipage allocation
In vm_phys_alloc_contig, for an allocation bigger than the size of any buddy queue free block, avoid examining any maximum-size free block more than twice, by only starting to consider a sequence of adjacent max-blocks starting at a max-block that does not follow another max-block. If that first max-block follows adjacent blocks of smaller size, and if together they provide enough memory to reduce by one the number of max-blocks required for this allocation, use them as part of this allocation. Reviewed by: markj Tested by: pho Discussed with: alc Differential Revision: https://reviews.freebsd.org/D34815
This commit is contained in:
Doug Moore
parent
651a887f4e
commit
fa8a6585c7
221
sys/vm/vm_phys.c
221
sys/vm/vm_phys.c
@ -1354,20 +1354,125 @@ vm_phys_unfree_page(vm_page_t m)
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}
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/*
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* Allocate a run of contiguous physical pages from the specified free list
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* Find a run of contiguous physical pages from the specified page list.
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*/
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static vm_page_t
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vm_phys_find_freelist_contig(struct vm_freelist *fl, int oind, u_long npages,
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vm_paddr_t low, vm_paddr_t high, u_long alignment, vm_paddr_t boundary)
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{
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struct vm_phys_seg *seg;
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vm_paddr_t frag, lbound, pa, page_size, pa_end, pa_pre, size;
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vm_page_t m, m_listed, m_ret;
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int order;
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KASSERT(npages > 0, ("npages is 0"));
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KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
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KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
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/* Search for a run satisfying the specified conditions. */
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page_size = PAGE_SIZE;
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size = npages << PAGE_SHIFT;
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frag = (npages & ~(~0UL << oind)) << PAGE_SHIFT;
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TAILQ_FOREACH(m_listed, &fl[oind].pl, listq) {
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/*
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* Determine if the address range starting at pa is
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* too low.
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*/
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pa = VM_PAGE_TO_PHYS(m_listed);
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if (pa < low)
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continue;
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/*
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* If this is not the first free oind-block in this range, bail
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* out. We have seen the first free block already, or will see
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* it before failing to find an appropriate range.
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*/
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seg = &vm_phys_segs[m_listed->segind];
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lbound = low > seg->start ? low : seg->start;
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pa_pre = pa - (page_size << oind);
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m = &seg->first_page[atop(pa_pre - seg->start)];
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if (pa != 0 && pa_pre >= lbound && m->order == oind)
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continue;
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if (!vm_addr_align_ok(pa, alignment))
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/* Advance to satisfy alignment condition. */
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pa = roundup2(pa, alignment);
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else if (frag != 0 && lbound + frag <= pa) {
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/*
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* Back up to the first aligned free block in this
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* range, without moving below lbound.
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*/
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pa_end = pa;
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for (order = oind - 1; order >= 0; order--) {
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pa_pre = pa_end - (page_size << order);
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if (!vm_addr_align_ok(pa_pre, alignment))
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break;
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m = &seg->first_page[atop(pa_pre - seg->start)];
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if (pa_pre >= lbound && m->order == order)
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pa_end = pa_pre;
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}
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/*
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* If the extra small blocks are enough to complete the
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* fragment, use them. Otherwise, look to allocate the
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* fragment at the other end.
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*/
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if (pa_end + frag <= pa)
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pa = pa_end;
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}
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/* Advance as necessary to satisfy boundary conditions. */
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if (!vm_addr_bound_ok(pa, size, boundary))
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pa = roundup2(pa + 1, boundary);
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pa_end = pa + size;
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/*
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* Determine if the address range is valid (without overflow in
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* pa_end calculation), and fits within the segment.
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*/
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if (pa_end < pa || seg->end < pa_end)
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continue;
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m_ret = &seg->first_page[atop(pa - seg->start)];
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/*
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* Determine whether there are enough free oind-blocks here to
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* satisfy the allocation request.
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*/
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pa = VM_PAGE_TO_PHYS(m_listed);
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do {
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pa += page_size << oind;
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if (pa >= pa_end)
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return (m_ret);
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m = &seg->first_page[atop(pa - seg->start)];
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} while (oind == m->order);
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/*
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* Determine if an additional series of free blocks of
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* diminishing size can help to satisfy the allocation request.
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*/
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while (m->order < oind &&
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pa + 2 * (page_size << m->order) > pa_end) {
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pa += page_size << m->order;
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if (pa >= pa_end)
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return (m_ret);
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m = &seg->first_page[atop(pa - seg->start)];
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}
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}
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return (NULL);
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}
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/*
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* Find a run of contiguous physical pages from the specified free list
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* table.
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*/
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static vm_page_t
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vm_phys_alloc_queues_contig(
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vm_phys_find_queues_contig(
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struct vm_freelist (*queues)[VM_NFREEPOOL][VM_NFREEORDER_MAX],
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u_long npages, vm_paddr_t low, vm_paddr_t high,
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u_long alignment, vm_paddr_t boundary)
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{
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struct vm_phys_seg *seg;
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struct vm_freelist *fl;
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vm_page_t m_ret;
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vm_paddr_t pa, pa_end, size;
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vm_page_t m, m_ret;
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u_long npages_end;
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int oind, order, pind;
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KASSERT(npages > 0, ("npages is 0"));
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@ -1375,10 +1480,9 @@ vm_phys_alloc_queues_contig(
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KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
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/* Compute the queue that is the best fit for npages. */
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order = flsl(npages - 1);
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/* Search for a run satisfying the specified conditions. */
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/* Search for a large enough free block. */
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size = npages << PAGE_SHIFT;
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for (oind = min(order, VM_NFREEORDER - 1); oind < VM_NFREEORDER;
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oind++) {
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for (oind = order; oind < VM_NFREEORDER; oind++) {
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for (pind = 0; pind < VM_NFREEPOOL; pind++) {
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fl = (*queues)[pind];
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TAILQ_FOREACH(m_ret, &fl[oind].pl, listq) {
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@ -1390,74 +1494,24 @@ vm_phys_alloc_queues_contig(
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*/
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pa = VM_PAGE_TO_PHYS(m_ret);
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pa_end = pa + size;
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if (pa < low || pa_end > high ||
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!vm_addr_ok(pa, size, alignment, boundary))
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continue;
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/*
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* Is the size of this allocation request
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* no more than the largest block size?
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*/
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if (order < VM_NFREEORDER)
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goto done;
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/*
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* Determine if the address range is valid
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* (without overflow in pa_end calculation)
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* and fits within the segment.
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*/
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seg = &vm_phys_segs[m_ret->segind];
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if (pa_end < pa || seg->end < pa_end)
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continue;
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/*
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* Determine if a series of free oind-blocks
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* starting here can satisfy the allocation
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* request.
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*/
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do {
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pa += 1 <<
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(PAGE_SHIFT + VM_NFREEORDER - 1);
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if (pa >= pa_end)
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goto done;
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} while (VM_NFREEORDER - 1 == seg->first_page[
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atop(pa - seg->start)].order);
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/*
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* Determine if an additional series of free
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* blocks of diminishing size can help to
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* satisfy the allocation request.
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*/
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for (;;) {
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m = &seg->first_page[
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atop(pa - seg->start)];
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if (m->order == VM_NFREEORDER ||
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pa + (2 << (PAGE_SHIFT + m->order))
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<= pa_end)
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break;
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pa += 1 << (PAGE_SHIFT + m->order);
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if (pa >= pa_end)
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goto done;
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}
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if (low <= pa && pa_end <= high &&
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vm_addr_ok(pa, size, alignment, boundary))
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return (m_ret);
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}
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}
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}
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if (order < VM_NFREEORDER)
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return (NULL);
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/* Search for a long-enough sequence of small blocks. */
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oind = VM_NFREEORDER - 1;
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for (pind = 0; pind < VM_NFREEPOOL; pind++) {
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fl = (*queues)[pind];
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m_ret = vm_phys_find_freelist_contig(fl, oind, npages,
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low, high, alignment, boundary);
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if (m_ret != NULL)
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return (m_ret);
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}
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return (NULL);
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done:
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for (m = m_ret; m < &m_ret[npages]; m = &m[1 << oind]) {
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fl = (*queues)[m->pool];
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oind = m->order;
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vm_freelist_rem(fl, m, oind);
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if (m->pool != VM_FREEPOOL_DEFAULT)
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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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npages_end = roundup2(npages, 1 << oind);
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if (npages < npages_end) {
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fl = (*queues)[VM_FREEPOOL_DEFAULT];
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vm_phys_enq_range(&m_ret[npages], npages_end - npages, fl, 0);
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}
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return (m_ret);
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}
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/*
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@ -1475,10 +1529,11 @@ vm_phys_alloc_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
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u_long alignment, vm_paddr_t boundary)
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{
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vm_paddr_t pa_end, pa_start;
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vm_page_t m_run;
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struct vm_freelist *fl;
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vm_page_t m, m_run;
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struct vm_phys_seg *seg;
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struct vm_freelist (*queues)[VM_NFREEPOOL][VM_NFREEORDER_MAX];
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int segind;
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int oind, segind;
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KASSERT(npages > 0, ("npages is 0"));
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KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
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@ -1513,11 +1568,27 @@ vm_phys_alloc_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
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if (seg->free_queues == queues)
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continue;
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queues = seg->free_queues;
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m_run = vm_phys_alloc_queues_contig(queues, npages,
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m_run = vm_phys_find_queues_contig(queues, npages,
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low, high, alignment, boundary);
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if (m_run != NULL)
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break;
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}
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if (m_run == NULL)
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return (NULL);
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/* Allocate pages from the page-range found. */
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for (m = m_run; m < &m_run[npages]; m = &m[1 << oind]) {
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fl = (*queues)[m->pool];
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oind = m->order;
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vm_freelist_rem(fl, m, oind);
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if (m->pool != VM_FREEPOOL_DEFAULT)
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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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return (m_run);
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}
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