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 11/13] rbtree: optimize case selection logic in __rb_erase_color() Date: Mon, 9 Jul 2012 16:35:21 -0700 [thread overview] Message-ID: <1341876923-12469-12-git-send-email-walken@google.com> (raw) In-Reply-To: <1341876923-12469-1-git-send-email-walken@google.com> In __rb_erase_color(), we have to select one of 3 cases depending on the color on the 'other' node children. If both children are black, we flip a few node colors and iterate. Otherwise, we do either one or two tree rotations, depending on the color of the 'other' child opposite to 'node', and then we are done. The corresponding logic had duplicate checks for the color of the 'other' child opposite to 'node'. It was checking it first to determine if both children are black, and then to determine how many tree rotations are required. Rearrange the logic to avoid that extra check. Signed-off-by: Michel Lespinasse <walken@google.com> --- lib/rbtree.c | 68 +++++++++++++++++++++++++-------------------------------- 1 files changed, 30 insertions(+), 38 deletions(-) diff --git a/lib/rbtree.c b/lib/rbtree.c index 44cbbd5..597c1b9 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -233,28 +233,24 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, __rb_rotate_left(parent, root); other = parent->rb_right; } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); - } - else - { - if (!other->rb_right || rb_is_black(other->rb_right)) - { - rb_set_black(other->rb_left); + if (!other->rb_right || rb_is_black(other->rb_right)) { + if (!other->rb_left || + rb_is_black(other->rb_left)) { rb_set_red(other); - __rb_rotate_right(other, root); - other = parent->rb_right; + node = parent; + parent = rb_parent(node); + continue; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - rb_set_black(other->rb_right); - __rb_rotate_left(parent, root); - break; + rb_set_black(other->rb_left); + rb_set_red(other); + __rb_rotate_right(other, root); + other = parent->rb_right; } + rb_set_color(other, rb_color(parent)); + rb_set_black(parent); + rb_set_black(other->rb_right); + __rb_rotate_left(parent, root); + break; } else { other = parent->rb_left; if (rb_is_red(other)) @@ -264,28 +260,24 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, __rb_rotate_right(parent, root); other = parent->rb_left; } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); - } - else - { - if (!other->rb_left || rb_is_black(other->rb_left)) - { - rb_set_black(other->rb_right); + if (!other->rb_left || rb_is_black(other->rb_left)) { + if (!other->rb_right || + rb_is_black(other->rb_right)) { rb_set_red(other); - __rb_rotate_left(other, root); - other = parent->rb_left; + node = parent; + parent = rb_parent(node); + continue; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - rb_set_black(other->rb_left); - __rb_rotate_right(parent, root); - break; + rb_set_black(other->rb_right); + rb_set_red(other); + __rb_rotate_left(other, root); + other = parent->rb_left; } + rb_set_color(other, rb_color(parent)); + rb_set_black(parent); + rb_set_black(other->rb_left); + __rb_rotate_right(parent, root); + 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 11/13] rbtree: optimize case selection logic in __rb_erase_color() Date: Mon, 9 Jul 2012 16:35:21 -0700 [thread overview] Message-ID: <1341876923-12469-12-git-send-email-walken@google.com> (raw) In-Reply-To: <1341876923-12469-1-git-send-email-walken@google.com> In __rb_erase_color(), we have to select one of 3 cases depending on the color on the 'other' node children. If both children are black, we flip a few node colors and iterate. Otherwise, we do either one or two tree rotations, depending on the color of the 'other' child opposite to 'node', and then we are done. The corresponding logic had duplicate checks for the color of the 'other' child opposite to 'node'. It was checking it first to determine if both children are black, and then to determine how many tree rotations are required. Rearrange the logic to avoid that extra check. Signed-off-by: Michel Lespinasse <walken@google.com> --- lib/rbtree.c | 68 +++++++++++++++++++++++++-------------------------------- 1 files changed, 30 insertions(+), 38 deletions(-) diff --git a/lib/rbtree.c b/lib/rbtree.c index 44cbbd5..597c1b9 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -233,28 +233,24 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, __rb_rotate_left(parent, root); other = parent->rb_right; } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); - } - else - { - if (!other->rb_right || rb_is_black(other->rb_right)) - { - rb_set_black(other->rb_left); + if (!other->rb_right || rb_is_black(other->rb_right)) { + if (!other->rb_left || + rb_is_black(other->rb_left)) { rb_set_red(other); - __rb_rotate_right(other, root); - other = parent->rb_right; + node = parent; + parent = rb_parent(node); + continue; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - rb_set_black(other->rb_right); - __rb_rotate_left(parent, root); - break; + rb_set_black(other->rb_left); + rb_set_red(other); + __rb_rotate_right(other, root); + other = parent->rb_right; } + rb_set_color(other, rb_color(parent)); + rb_set_black(parent); + rb_set_black(other->rb_right); + __rb_rotate_left(parent, root); + break; } else { other = parent->rb_left; if (rb_is_red(other)) @@ -264,28 +260,24 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, __rb_rotate_right(parent, root); other = parent->rb_left; } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); - } - else - { - if (!other->rb_left || rb_is_black(other->rb_left)) - { - rb_set_black(other->rb_right); + if (!other->rb_left || rb_is_black(other->rb_left)) { + if (!other->rb_right || + rb_is_black(other->rb_right)) { rb_set_red(other); - __rb_rotate_left(other, root); - other = parent->rb_left; + node = parent; + parent = rb_parent(node); + continue; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - rb_set_black(other->rb_left); - __rb_rotate_right(parent, root); - break; + rb_set_black(other->rb_right); + rb_set_red(other); + __rb_rotate_left(other, root); + other = parent->rb_left; } + rb_set_color(other, rb_color(parent)); + rb_set_black(parent); + rb_set_black(other->rb_left); + __rb_rotate_right(parent, root); + break; } } } -- 1.7.7.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-07-09 23:36 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 ` [PATCH 08/13] rbtree: optimize tree rotations in rb_insert_color() Michel Lespinasse 2012-07-09 23:35 ` 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 ` Michel Lespinasse [this message] 2012-07-09 23:35 ` [PATCH 11/13] rbtree: optimize case selection logic in __rb_erase_color() 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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