From ef327c3ee7ea81cce37616cf8c2b6f870520c80c Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Sun, 21 Jun 2009 20:29:14 +0000 Subject: [PATCH] Implement a mechanism within vm_phys_alloc_contig() to defer all necessary calls to vdrop() until after the free page queues lock is released. This eliminates repeatedly releasing and reacquiring the free page queues lock each time the last cached page is reclaimed from a vnode-backed object. --- sys/vm/vm_phys.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c index 0de35cd75dc9..f64bc9cf40a5 100644 --- a/sys/vm/vm_phys.c +++ b/sys/vm/vm_phys.c @@ -594,7 +594,7 @@ vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high, struct vm_phys_seg *seg; vm_object_t m_object; vm_paddr_t pa, pa_last, size; - vm_page_t m, m_ret; + vm_page_t deferred_vdrop_list, m, m_ret; int flind, i, oind, order, pind; size = npages << PAGE_SHIFT; @@ -604,6 +604,7 @@ vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high, ("vm_phys_alloc_contig: alignment must be a power of 2")); KASSERT((boundary & (boundary - 1)) == 0, ("vm_phys_alloc_contig: boundary must be a power of 2")); + deferred_vdrop_list = NULL; /* Compute the queue that is the best fit for npages. */ for (order = 0; (1 << order) < npages; order++); mtx_lock(&vm_page_queue_free_mtx); @@ -697,10 +698,23 @@ vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high, ("vm_phys_alloc_contig: page %p is busy", m)); KASSERT(m->dirty == 0, ("vm_phys_alloc_contig: page %p is dirty", m)); - m_object = m->object; if ((m->flags & PG_CACHED) != 0) { m->valid = 0; + m_object = m->object; vm_page_cache_remove(m); + if (m_object->type == OBJT_VNODE && + m_object->cache == NULL) { + /* + * Enqueue the vnode for deferred vdrop(). + * + * Unmanaged pages don't use "pageq", so it + * can be safely abused to construct a short- + * lived queue of vnodes. + */ + m->pageq.tqe_prev = m_object->handle; + m->pageq.tqe_next = deferred_vdrop_list; + deferred_vdrop_list = m; + } } else { KASSERT(VM_PAGE_IS_FREE(m), ("vm_phys_alloc_contig: page %p is not free", m)); @@ -714,13 +728,6 @@ vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high, m->flags = PG_UNMANAGED | (m->flags & PG_ZERO); m->oflags = 0; /* Unmanaged pages don't use "act_count". */ - if (m_object != NULL && - m_object->type == OBJT_VNODE && - m_object->cache == NULL) { - mtx_unlock(&vm_page_queue_free_mtx); - vdrop(m_object->handle); - mtx_lock(&vm_page_queue_free_mtx); - } } for (; i < roundup2(npages, 1 << imin(oind, order)); i++) { m = &m_ret[i]; @@ -730,6 +737,10 @@ vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high, vm_phys_free_pages(m, 0); } mtx_unlock(&vm_page_queue_free_mtx); + while (deferred_vdrop_list != NULL) { + vdrop((struct vnode *)deferred_vdrop_list->pageq.tqe_prev); + deferred_vdrop_list = deferred_vdrop_list->pageq.tqe_next; + } return (m_ret); }