[CC Johannes and Vladimir - the whole series is http://lkml.kernel.org/r/[email protected]]
On Tue 18-07-17 18:46:02, Davidlohr Bueso wrote: > 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. The soft limit reclaim and the associated tree manipulation is not worth touching/optimizing IMHO. We strongly discourage anybody configuring soft limit because of the way how it is implemented and disruptive. > Signed-off-by: Davidlohr Bueso <[email protected]> > --- > 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 -- Michal Hocko SUSE Labs
