From: Davidlohr Bueso <dave@stgolabs.net> To: akpm@linux-foundation.org Cc: mingo@kernel.org, peterz@infradead.org, jack@suse.cz, torvalds@linux-foundation.org, kirill.shutemov@linux.intel.com, hch@infradead.org, ldufour@linux.vnet.ibm.com, mhocko@suse.com, mgorman@techsingularity.net, dave@stgolabs.net, linux-kernel@vger.kernel.org, axboe@fb.com, linux-block@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de> Subject: [PATCH 17/17] block/cfq: cache rightmost rb_node Date: Tue, 18 Jul 2017 18:46:03 -0700 Message-ID: <20170719014603.19029-18-dave@stgolabs.net> (raw) In-Reply-To: <20170719014603.19029-1-dave@stgolabs.net> For the same reasons we already cache the leftmost pointer, apply the same optimization for rb_last() calls. Users must explicitly do this as rb_root_cached only deals with the smallest node. Cc: axboe@fb.com Cc: linux-block@vger.kernel.org Signed-off-by: Davidlohr Bueso <dbueso@suse.de> --- This is part of the rbtree internal caching series: https://lwn.net/Articles/726809/ block/cfq-iosched.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 92c31683a2bb..57ec45fd4590 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -94,11 +94,13 @@ struct cfq_ttime { */ struct cfq_rb_root { struct rb_root_cached rb; + struct rb_node *rb_rightmost; unsigned count; u64 min_vdisktime; struct cfq_ttime ttime; }; #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT_CACHED, \ + .rb_rightmost = NULL, \ .ttime = {.last_end_request = ktime_get_ns(),},} /* @@ -1183,6 +1185,9 @@ static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) { + if (root->rb_rightmost == n) + root->rb_rightmost = rb_next(n); + rb_erase_cached(n, &root->rb); RB_CLEAR_NODE(n); @@ -1239,20 +1244,24 @@ __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) struct rb_node *parent = NULL; struct cfq_group *__cfqg; s64 key = cfqg_key(st, cfqg); - bool leftmost = true; + bool leftmost = true, rightmost = true; while (*node != NULL) { parent = *node; __cfqg = rb_entry_cfqg(parent); - if (key < cfqg_key(st, __cfqg)) + if (key < cfqg_key(st, __cfqg)) { node = &parent->rb_left; - else { + rightmost = false; + } else { node = &parent->rb_right; leftmost = false; } } + if (rightmost) + st->rb_rightmost = &cfqg->rb_node; + rb_link_node(&cfqg->rb_node, parent, node); rb_insert_color_cached(&cfqg->rb_node, &st->rb, leftmost); } @@ -1355,7 +1364,7 @@ cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) * so that groups get lesser vtime based on their weights, so that * if group does not loose all if it was not continuously backlogged. */ - n = rb_last(&st->rb.rb_root); + n = st->rb_rightmost; if (n) { __cfqg = rb_entry_cfqg(n); cfqg->vdisktime = __cfqg->vdisktime + @@ -2204,7 +2213,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq)); if (cfq_class_idle(cfqq)) { rb_key = CFQ_IDLE_DELAY; - parent = rb_last(&st->rb.rb_root); + parent = st->rb_rightmost; if (parent && parent != &cfqq->rb_node) { __cfqq = rb_entry(parent, struct cfq_queue, rb_node); rb_key += __cfqq->rb_key; -- 2.12.0
next prev parent reply index Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-07-19 1:45 [PATCH -next v4 00/17] rbtree: cache leftmost node internally Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 01/17] " Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 02/17] rbtree: optimize root-check during rebalancing loop Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 03/17] rbtree: add some additional comments for rebalancing cases Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 04/17] lib/rbtree_test.c: make input module parameters Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 05/17] lib/rbtree_test.c: add (inorder) traversal test Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 06/17] lib/rbtree_test.c: support rb_root_cached Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 07/17] sched/fair: replace cfs_rq->rb_leftmost Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 08/17] sched/deadline: replace earliest dl and rq leftmost caching Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 09/17] locking/rtmutex: replace top-waiter and pi_waiters " Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 10/17] block/cfq: replace cfq_rb_root " Davidlohr Bueso 2017-07-19 7:46 ` Jan Kara 2017-07-19 1:45 ` [PATCH 11/17] lib/interval_tree: fast overlap detection Davidlohr Bueso 2017-07-22 17:52 ` Doug Ledford 2017-08-01 17:16 ` Michael S. Tsirkin 2017-07-19 1:45 ` [PATCH 12/17] lib/interval-tree: correct comment wrt generic flavor Davidlohr Bueso 2017-07-19 1:45 ` [PATCH 13/17] procfs: use faster rb_first_cached() Davidlohr Bueso 2017-07-19 1:46 ` [PATCH 14/17] fs/epoll: " Davidlohr Bueso 2017-07-19 1:46 ` [PATCH 15/17] fs/ext4: use cached rbtrees Davidlohr Bueso 2017-07-19 7:40 ` Jan Kara 2017-07-19 22:50 ` Davidlohr Bueso 2017-07-19 1:46 ` [PATCH 16/17] mem/memcg: cache rightmost node Davidlohr Bueso 2017-07-19 7:50 ` Michal Hocko 2017-07-26 21:09 ` Andrew Morton 2017-07-27 7:06 ` Michal Hocko 2017-07-19 1:46 ` Davidlohr Bueso [this message] 2017-07-19 7:59 ` [PATCH 17/17] block/cfq: cache rightmost rb_node Jan Kara
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