Change vm_page_unwire() such that it (1) accepts PQ_NONE as the specified
queue and (2) returns a Boolean indicating whether the page's wire count transitioned to zero. Exploit this change in vfs_vmio_release() to avoid pointlessly enqueueing a page that is about to be freed. (An earlier version of this change was developed by attilio@ and kmacy@. Any errors in this version are my own.) Reviewed by: kib Sponsored by: EMC / Isilon Storage Division
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parent
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commit
15aaea7892
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=288122
@ -2076,6 +2076,7 @@ vfs_vmio_release(struct buf *bp)
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vm_object_t obj;
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vm_page_t m;
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int i;
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bool freed;
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if (buf_mapped(bp)) {
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BUF_CHECK_MAPPED(bp);
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@ -2088,23 +2089,28 @@ vfs_vmio_release(struct buf *bp)
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for (i = 0; i < bp->b_npages; i++) {
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m = bp->b_pages[i];
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bp->b_pages[i] = NULL;
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/*
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* In order to keep page LRU ordering consistent, put
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* everything on the inactive queue.
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*/
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vm_page_lock(m);
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vm_page_unwire(m, PQ_INACTIVE);
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/*
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* Might as well free the page if we can and it has
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* no valid data. We also free the page if the
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* buffer was used for direct I/O
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*/
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if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) {
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if (m->wire_count == 0 && !vm_page_busied(m))
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vm_page_free(m);
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} else if (bp->b_flags & B_DIRECT)
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vm_page_try_to_free(m);
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if (vm_page_unwire(m, PQ_NONE)) {
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/*
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* Determine if the page should be freed before adding
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* it to the inactive queue.
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*/
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if ((bp->b_flags & B_ASYNC) == 0 && m->valid == 0) {
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freed = !vm_page_busied(m);
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if (freed)
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vm_page_free(m);
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} else if ((bp->b_flags & B_DIRECT) != 0)
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freed = vm_page_try_to_free(m);
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else
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freed = false;
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if (!freed) {
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/*
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* In order to maintain LRU page ordering, put
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* the page at the tail of the inactive queue.
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*/
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vm_page_deactivate(m);
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}
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}
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vm_page_unlock(m);
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}
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if (obj != NULL)
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@ -2476,42 +2476,46 @@ vm_page_wire(vm_page_t m)
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/*
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* vm_page_unwire:
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*
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* Release one wiring of the specified page, potentially enabling it to be
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* paged again. If paging is enabled, then the value of the parameter
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* "queue" determines the queue to which the page is added.
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* Release one wiring of the specified page, potentially allowing it to be
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* paged out. Returns TRUE if the number of wirings transitions to zero and
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* FALSE otherwise.
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*
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* However, unless the page belongs to an object, it is not enqueued because
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* it cannot be paged out.
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* Only managed pages belonging to an object can be paged out. If the number
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* of wirings transitions to zero and the page is eligible for page out, then
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* the page is added to the specified paging queue (unless PQ_NONE is
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* specified).
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*
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* If a page is fictitious, then its wire count must always be one.
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*
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* A managed page must be locked.
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*/
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void
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boolean_t
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vm_page_unwire(vm_page_t m, uint8_t queue)
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{
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KASSERT(queue < PQ_COUNT,
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KASSERT(queue < PQ_COUNT || queue == PQ_NONE,
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("vm_page_unwire: invalid queue %u request for page %p",
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queue, m));
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if ((m->oflags & VPO_UNMANAGED) == 0)
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vm_page_lock_assert(m, MA_OWNED);
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vm_page_assert_locked(m);
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if ((m->flags & PG_FICTITIOUS) != 0) {
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KASSERT(m->wire_count == 1,
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("vm_page_unwire: fictitious page %p's wire count isn't one", m));
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return;
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return (FALSE);
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}
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if (m->wire_count > 0) {
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m->wire_count--;
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if (m->wire_count == 0) {
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atomic_subtract_int(&vm_cnt.v_wire_count, 1);
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if ((m->oflags & VPO_UNMANAGED) != 0 ||
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m->object == NULL)
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return;
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if (queue == PQ_INACTIVE)
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m->flags &= ~PG_WINATCFLS;
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vm_page_enqueue(queue, m);
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}
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if ((m->oflags & VPO_UNMANAGED) == 0 &&
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m->object != NULL && queue != PQ_NONE) {
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if (queue == PQ_INACTIVE)
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m->flags &= ~PG_WINATCFLS;
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vm_page_enqueue(queue, m);
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}
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return (TRUE);
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} else
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return (FALSE);
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} else
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panic("vm_page_unwire: page %p's wire count is zero", m);
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}
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@ -480,7 +480,7 @@ vm_offset_t vm_page_startup(vm_offset_t vaddr);
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void vm_page_sunbusy(vm_page_t m);
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int vm_page_trysbusy(vm_page_t m);
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void vm_page_unhold_pages(vm_page_t *ma, int count);
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void vm_page_unwire (vm_page_t m, uint8_t queue);
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boolean_t vm_page_unwire(vm_page_t m, uint8_t queue);
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void vm_page_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr);
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void vm_page_wire (vm_page_t);
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void vm_page_xunbusy_hard(vm_page_t m);
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