The patch titled
Subject: mem/memcg: cache rightmost node
has been added to the -mm tree. Its filename is
mem-memcg-cache-rightmost-node.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mem-memcg-cache-rightmost-node.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mem-memcg-cache-rightmost-node.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: mem/memcg: cache rightmost node
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.
Link: http://lkml.kernel.org/r/20170719014603.19029-17-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff -puN mm/memcontrol.c~mem-memcg-cache-rightmost-node mm/memcontrol.c
--- a/mm/memcontrol.c~mem-memcg-cache-rightmost-node
+++ a/mm/memcontrol.c
@@ -119,6 +119,7 @@ static const char *const mem_cgroup_lru_
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 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
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
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
{
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
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
@@ -5855,6 +5867,7 @@ 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;
}
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
rbtree-cache-leftmost-node-internally.patch
rbtree-optimize-root-check-during-rebalancing-loop.patch
rbtree-add-some-additional-comments-for-rebalancing-cases.patch
lib-rbtree_testc-make-input-module-parameters.patch
lib-rbtree_testc-add-inorder-traversal-test.patch
lib-rbtree_testc-support-rb_root_cached.patch
sched-fair-replace-cfs_rq-rb_leftmost.patch
sched-deadline-replace-earliest-dl-and-rq-leftmost-caching.patch
locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching.patch
block-cfq-replace-cfq_rb_root-leftmost-caching.patch
lib-interval_tree-fast-overlap-detection.patch
lib-interval-tree-correct-comment-wrt-generic-flavor.patch
procfs-use-faster-rb_first_cached.patch
fs-epoll-use-faster-rb_first_cached.patch
mem-memcg-cache-rightmost-node.patch
block-cfq-cache-rightmost-rb_node.patch
--
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