From akpm@linux-foundation.org Wed Mar 12 14:44:30 2008 From: mark gross Date: Tue, 04 Mar 2008 15:22:04 -0800 Subject: PCI: iova RB tree setup tweak To: greg@kroah.com Cc: linux-pci@atrey.karlin.mff.cuni.cz, akpm@linux-foundation.org, mgross@linux.intel.com Message-ID: <200803042322.m24NM4oW002958@imap1.linux-foundation.org> From: mark gross The following patch merges two functions into one allowing for a 3% reduction in overhead in locating, allocating and inserting pages for use in IOMMU operations. Its a bit of a eye-crosser so I welcome any RB-tree / MM experts to take a look. It works by re-using some of the information gathered in the search for the pages to use in setting up the IOTLB's in the insertion of the iova structure into the RB tree. Signed-off-by: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/pci/iova.c | 50 ++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 36 insertions(+), 14 deletions(-) --- a/drivers/pci/iova.c +++ b/drivers/pci/iova.c @@ -73,10 +73,11 @@ iova_get_pad_size(int size, unsigned int return pad_size; } -static int __alloc_iova_range(struct iova_domain *iovad, unsigned long size, - unsigned long limit_pfn, struct iova *new, bool size_aligned) +static int __alloc_and_insert_iova_range(struct iova_domain *iovad, + unsigned long size, unsigned long limit_pfn, + struct iova *new, bool size_aligned) { - struct rb_node *curr = NULL; + struct rb_node *prev, *curr = NULL; unsigned long flags; unsigned long saved_pfn; unsigned int pad_size = 0; @@ -85,8 +86,10 @@ static int __alloc_iova_range(struct iov spin_lock_irqsave(&iovad->iova_rbtree_lock, flags); saved_pfn = limit_pfn; curr = __get_cached_rbnode(iovad, &limit_pfn); + prev = curr; while (curr) { struct iova *curr_iova = container_of(curr, struct iova, node); + if (limit_pfn < curr_iova->pfn_lo) goto move_left; else if (limit_pfn < curr_iova->pfn_hi) @@ -100,6 +103,7 @@ static int __alloc_iova_range(struct iov adjust_limit_pfn: limit_pfn = curr_iova->pfn_lo - 1; move_left: + prev = curr; curr = rb_prev(curr); } @@ -116,7 +120,33 @@ move_left: new->pfn_lo = limit_pfn - (size + pad_size) + 1; new->pfn_hi = new->pfn_lo + size - 1; + /* Insert the new_iova into domain rbtree by holding writer lock */ + /* Add new node and rebalance tree. */ + { + struct rb_node **entry = &((prev)), *parent = NULL; + /* Figure out where to put new node */ + while (*entry) { + struct iova *this = container_of(*entry, + struct iova, node); + parent = *entry; + + if (new->pfn_lo < this->pfn_lo) + entry = &((*entry)->rb_left); + else if (new->pfn_lo > this->pfn_lo) + entry = &((*entry)->rb_right); + else + BUG(); /* this should not happen */ + } + + /* Add new node and rebalance tree. */ + rb_link_node(&new->node, parent, entry); + rb_insert_color(&new->node, &iovad->rbroot); + } + __cached_rbnode_insert_update(iovad, saved_pfn, new); + spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags); + + return 0; } @@ -172,23 +202,15 @@ alloc_iova(struct iova_domain *iovad, un size = __roundup_pow_of_two(size); spin_lock_irqsave(&iovad->iova_alloc_lock, flags); - ret = __alloc_iova_range(iovad, size, limit_pfn, new_iova, - size_aligned); + ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn, + new_iova, size_aligned); + spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags); if (ret) { - spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags); free_iova_mem(new_iova); return NULL; } - /* Insert the new_iova into domain rbtree by holding writer lock */ - spin_lock(&iovad->iova_rbtree_lock); - iova_insert_rbtree(&iovad->rbroot, new_iova); - __cached_rbnode_insert_update(iovad, limit_pfn, new_iova); - spin_unlock(&iovad->iova_rbtree_lock); - - spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags); - return new_iova; }