From: Michel Lespinasse <walken@google.com> To: aarcange@redhat.com, dwmw2@infradead.org, riel@redhat.com, peterz@infradead.org, daniel.santos@pobox.com, axboe@kernel.dk, ebiederm@xmission.com Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org Subject: [PATCH 08/13] rbtree: optimize tree rotations in rb_insert_color() Date: Mon, 9 Jul 2012 16:35:18 -0700 [thread overview] Message-ID: <1341876923-12469-9-git-send-email-walken@google.com> (raw) In-Reply-To: <1341876923-12469-1-git-send-email-walken@google.com> In rb_insert_color(), we can do better than calling __rb_rotate_left() and __rb_rotate_right() to handle tree rotations: we already have pointers to all relevant nodes, and know their colors (either because we want to adjust it, or because we've tested it, or we can deduce it as black due to the node proximity to a known red node). So we can generate more efficient code by making use of the node pointers we already have, and setting both the parent and color attributes for nodes all at once. Also in case 2, some node attributes don't have to be set because we know another tree rotation (case 3) will always follow and override them. Signed-off-by: Michel Lespinasse <walken@google.com> --- lib/rbtree.c | 102 ++++++++++++++++++++++++++++++++++++++++----------------- 1 files changed, 71 insertions(+), 31 deletions(-) diff --git a/lib/rbtree.c b/lib/rbtree.c index 0d9d184..f668886 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -41,6 +41,12 @@ static inline void rb_set_color(struct rb_node *rb, int color) rb->rb_parent_color = (rb->rb_parent_color & ~1) | color; } +static inline void rb_set_parent_color(struct rb_node *rb, + struct rb_node *p, int color) +{ + rb->rb_parent_color = (unsigned long)p | color; +} + static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) { struct rb_node *right = node->rb_right; @@ -87,9 +93,30 @@ static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) rb_set_parent(node, left); } +/* + * Helper function for rotations: + * - old's parent and color get assigned to new + * - old gets assigned new as a parent and 'color' as a color. + */ +static inline void +__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new, + struct rb_root *root, int color) +{ + struct rb_node *parent = rb_parent(old); + new->rb_parent_color = old->rb_parent_color; + rb_set_parent_color(old, new, color); + if (parent) { + if (parent->rb_left == old) + parent->rb_left = new; + else + parent->rb_right = new; + } else + root->rb_node = new; +} + void rb_insert_color(struct rb_node *node, struct rb_root *root) { - struct rb_node *parent, *gparent; + struct rb_node *parent, *gparent, *tmp; while (true) { /* @@ -108,50 +135,63 @@ void rb_insert_color(struct rb_node *node, struct rb_root *root) gparent = rb_parent(parent); - if (parent == gparent->rb_left) - { - { - register struct rb_node *uncle = gparent->rb_right; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + if (parent == gparent->rb_left) { + tmp = gparent->rb_right; + if (tmp && rb_is_red(tmp)) { + /* Case 1 - color flips */ + rb_set_black(tmp); + rb_set_black(parent); + rb_set_red(gparent); + node = gparent; + continue; } if (parent->rb_right == node) { - __rb_rotate_left(parent, root); + /* Case 2 - left rotate at parent */ + parent->rb_right = tmp = node->rb_left; + node->rb_left = parent; + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); parent = node; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_right(gparent, root); + /* Case 3 - right rotate at gparent */ + gparent->rb_left = tmp = parent->rb_right; + parent->rb_right = gparent; + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); break; } else { - { - register struct rb_node *uncle = gparent->rb_left; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + tmp = gparent->rb_left; + if (tmp && rb_is_red(tmp)) { + /* Case 1 - color flips */ + rb_set_black(tmp); + rb_set_black(parent); + rb_set_red(gparent); + node = gparent; + continue; } if (parent->rb_left == node) { - __rb_rotate_right(parent, root); + /* Case 2 - right rotate at parent */ + parent->rb_left = tmp = node->rb_right; + node->rb_right = parent; + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); parent = node; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_left(gparent, root); + /* Case 3 - left rotate at gparent */ + gparent->rb_right = tmp = parent->rb_left; + parent->rb_left = gparent; + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); break; } } -- 1.7.7.3
WARNING: multiple messages have this Message-ID (diff)
From: Michel Lespinasse <walken@google.com> To: aarcange@redhat.com, dwmw2@infradead.org, riel@redhat.com, peterz@infradead.org, daniel.santos@pobox.com, axboe@kernel.dk, ebiederm@xmission.com Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org Subject: [PATCH 08/13] rbtree: optimize tree rotations in rb_insert_color() Date: Mon, 9 Jul 2012 16:35:18 -0700 [thread overview] Message-ID: <1341876923-12469-9-git-send-email-walken@google.com> (raw) In-Reply-To: <1341876923-12469-1-git-send-email-walken@google.com> In rb_insert_color(), we can do better than calling __rb_rotate_left() and __rb_rotate_right() to handle tree rotations: we already have pointers to all relevant nodes, and know their colors (either because we want to adjust it, or because we've tested it, or we can deduce it as black due to the node proximity to a known red node). So we can generate more efficient code by making use of the node pointers we already have, and setting both the parent and color attributes for nodes all at once. Also in case 2, some node attributes don't have to be set because we know another tree rotation (case 3) will always follow and override them. Signed-off-by: Michel Lespinasse <walken@google.com> --- lib/rbtree.c | 102 ++++++++++++++++++++++++++++++++++++++++----------------- 1 files changed, 71 insertions(+), 31 deletions(-) diff --git a/lib/rbtree.c b/lib/rbtree.c index 0d9d184..f668886 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -41,6 +41,12 @@ static inline void rb_set_color(struct rb_node *rb, int color) rb->rb_parent_color = (rb->rb_parent_color & ~1) | color; } +static inline void rb_set_parent_color(struct rb_node *rb, + struct rb_node *p, int color) +{ + rb->rb_parent_color = (unsigned long)p | color; +} + static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) { struct rb_node *right = node->rb_right; @@ -87,9 +93,30 @@ static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) rb_set_parent(node, left); } +/* + * Helper function for rotations: + * - old's parent and color get assigned to new + * - old gets assigned new as a parent and 'color' as a color. + */ +static inline void +__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new, + struct rb_root *root, int color) +{ + struct rb_node *parent = rb_parent(old); + new->rb_parent_color = old->rb_parent_color; + rb_set_parent_color(old, new, color); + if (parent) { + if (parent->rb_left == old) + parent->rb_left = new; + else + parent->rb_right = new; + } else + root->rb_node = new; +} + void rb_insert_color(struct rb_node *node, struct rb_root *root) { - struct rb_node *parent, *gparent; + struct rb_node *parent, *gparent, *tmp; while (true) { /* @@ -108,50 +135,63 @@ void rb_insert_color(struct rb_node *node, struct rb_root *root) gparent = rb_parent(parent); - if (parent == gparent->rb_left) - { - { - register struct rb_node *uncle = gparent->rb_right; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + if (parent == gparent->rb_left) { + tmp = gparent->rb_right; + if (tmp && rb_is_red(tmp)) { + /* Case 1 - color flips */ + rb_set_black(tmp); + rb_set_black(parent); + rb_set_red(gparent); + node = gparent; + continue; } if (parent->rb_right == node) { - __rb_rotate_left(parent, root); + /* Case 2 - left rotate at parent */ + parent->rb_right = tmp = node->rb_left; + node->rb_left = parent; + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); parent = node; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_right(gparent, root); + /* Case 3 - right rotate at gparent */ + gparent->rb_left = tmp = parent->rb_right; + parent->rb_right = gparent; + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); break; } else { - { - register struct rb_node *uncle = gparent->rb_left; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + tmp = gparent->rb_left; + if (tmp && rb_is_red(tmp)) { + /* Case 1 - color flips */ + rb_set_black(tmp); + rb_set_black(parent); + rb_set_red(gparent); + node = gparent; + continue; } if (parent->rb_left == node) { - __rb_rotate_right(parent, root); + /* Case 2 - right rotate at parent */ + parent->rb_left = tmp = node->rb_right; + node->rb_right = parent; + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); parent = node; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_left(gparent, root); + /* Case 3 - left rotate at gparent */ + gparent->rb_right = tmp = parent->rb_left; + parent->rb_left = gparent; + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); break; } } -- 1.7.7.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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next prev parent reply other threads:[~2012-07-09 23:35 UTC|newest] Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-07-09 23:35 [PATCH 00/13] rbtree updates Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 01/13] rbtree: reference Documentation/rbtree.txt for usage instructions Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-10 1:45 ` Rik van Riel 2012-07-10 1:45 ` Rik van Riel 2012-07-09 23:35 ` [PATCH 02/13] rbtree: empty nodes have no color Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-10 10:59 ` Daniel Santos 2012-07-10 10:59 ` Daniel Santos 2012-07-10 23:10 ` Michel Lespinasse 2012-07-10 23:10 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 03/13] rbtree: fix incorrect rbtree node insertion in fs/proc/proc_sysctl.c Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 04/13] rbtree: move some implementation details from rbtree.h to rbtree.c Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-10 12:19 ` Michal Nazarewicz 2012-07-10 12:19 ` Michal Nazarewicz 2012-07-10 23:12 ` Michel Lespinasse 2012-07-10 23:12 ` Michel Lespinasse 2012-07-11 15:48 ` Michal Nazarewicz 2012-07-11 15:48 ` Michal Nazarewicz 2012-07-09 23:35 ` [PATCH 05/13] rbtree: performance and correctness test Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-10 12:27 ` Michal Nazarewicz 2012-07-10 12:27 ` Michal Nazarewicz 2012-07-10 23:18 ` Michel Lespinasse 2012-07-10 23:18 ` Michel Lespinasse 2012-07-11 6:14 ` Michel Lespinasse 2012-07-11 6:14 ` Michel Lespinasse 2012-07-11 19:30 ` Daniel Santos 2012-07-11 19:30 ` Daniel Santos 2012-07-09 23:35 ` [PATCH 06/13] rbtree: break out of rb_insert_color loop after tree rotation Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 07/13] rbtree: adjust root color in rb_insert_color() only when necessary Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse [this message] 2012-07-09 23:35 ` [PATCH 08/13] rbtree: optimize tree rotations in rb_insert_color() Michel Lespinasse 2012-07-09 23:35 ` [PATCH 09/13] rbtree: optimize color flips and parent fetching " Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 10/13] rbtree: adjust node color in __rb_erase_color() only when necessary Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 11/13] rbtree: optimize case selection logic in __rb_erase_color() Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 12/13] rbtree: optimize tree rotations " Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-09 23:35 ` [PATCH 13/13] rbtree: optimize color flips " Michel Lespinasse 2012-07-09 23:35 ` Michel Lespinasse 2012-07-11 13:23 ` [PATCH 00/13] rbtree updates Peter Zijlstra 2012-07-11 13:23 ` Peter Zijlstra 2012-07-12 1:12 ` Michel Lespinasse 2012-07-12 1:12 ` Michel Lespinasse 2012-07-12 14:09 ` Peter Zijlstra 2012-07-12 14:09 ` Peter Zijlstra 2012-07-12 14:12 ` Peter Zijlstra 2012-07-12 14:12 ` Peter Zijlstra 2012-07-13 0:39 ` Michel Lespinasse 2012-07-13 0:39 ` Michel Lespinasse
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