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mem/memcg: cache rightmost node

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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.

[dave@stgolabs.net: brain fart #2]
  Link: http://lkml.kernel.org/r/20170731160114.GE21328@linux-80c1.suse
Link: http://lkml.kernel.org/r/20170719014603.19029-17-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Davidlohr Bueso 2017-09-08 16:15:21 -07:00 committed by Linus Torvalds
parent b2ac2ea629
commit fa90b2fd30
1 changed files with 18 additions and 5 deletions
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23
mm/memcontrol.c
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@ -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_prev(&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
@ -5945,6 +5957,7 @@ 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;
}