From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753197AbdGSBrv (ORCPT ); Tue, 18 Jul 2017 21:47:51 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:57523 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753119AbdGSBrs (ORCPT ); Tue, 18 Jul 2017 21:47:48 -0400 From: Davidlohr Bueso 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, Davidlohr Bueso Subject: [PATCH 16/17] mem/memcg: cache rightmost node Date: Tue, 18 Jul 2017 18:46:02 -0700 Message-Id: <20170719014603.19029-17-dave@stgolabs.net> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170719014603.19029-1-dave@stgolabs.net> References: <20170719014603.19029-1-dave@stgolabs.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Such that we can optimize __mem_cgroup_largest_soft_limit_node(). The only overhead is the extra footprint for the cached pointer, but this should not be an issue for mem_cgroup_tree_per_node. Signed-off-by: Davidlohr Bueso --- mm/memcontrol.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3df3c04d73ab..2ef9328ace2e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -119,6 +119,7 @@ static const char *const mem_cgroup_lru_names[] = { struct mem_cgroup_tree_per_node { struct rb_root rb_root; + struct rb_node *rb_rightmost; spinlock_t lock; }; @@ -386,6 +387,7 @@ static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, struct rb_node **p = &mctz->rb_root.rb_node; struct rb_node *parent = NULL; struct mem_cgroup_per_node *mz_node; + bool rightmost = true; if (mz->on_tree) return; @@ -397,8 +399,11 @@ static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, parent = *p; mz_node = rb_entry(parent, struct mem_cgroup_per_node, tree_node); - if (mz->usage_in_excess < mz_node->usage_in_excess) + if (mz->usage_in_excess < mz_node->usage_in_excess) { p = &(*p)->rb_left; + rightmost = false; + } + /* * We can't avoid mem cgroups that are over their soft * limit by the same amount @@ -406,6 +411,10 @@ static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, else if (mz->usage_in_excess >= mz_node->usage_in_excess) p = &(*p)->rb_right; } + + if (rightmost) + mctz->rb_rightmost = &mz->tree_node; + rb_link_node(&mz->tree_node, parent, p); rb_insert_color(&mz->tree_node, &mctz->rb_root); mz->on_tree = true; @@ -416,6 +425,10 @@ static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz, { if (!mz->on_tree) return; + + if (&mz->tree_node == mctz->rb_rightmost) + mctz->rb_rightmost = rb_next(&mz->tree_node); + rb_erase(&mz->tree_node, &mctz->rb_root); mz->on_tree = false; } @@ -496,16 +509,15 @@ static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) static struct mem_cgroup_per_node * __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) { - struct rb_node *rightmost = NULL; struct mem_cgroup_per_node *mz; retry: mz = NULL; - rightmost = rb_last(&mctz->rb_root); - if (!rightmost) + if (!mctz->rb_rightmost) goto done; /* Nothing to reclaim from */ - mz = rb_entry(rightmost, struct mem_cgroup_per_node, tree_node); + mz = rb_entry(mctz->rb_rightmost, + struct mem_cgroup_per_node, tree_node); /* * Remove the node now but someone else can add it back, * we will to add it back at the end of reclaim to its correct @@ -5850,6 +5862,7 @@ static int __init mem_cgroup_init(void) node_online(node) ? node : NUMA_NO_NODE); rtpn->rb_root = RB_ROOT; + rtpn->rb_rightmost = NULL; spin_lock_init(&rtpn->lock); soft_limit_tree.rb_tree_per_node[node] = rtpn; } -- 2.12.0