Skip to content

Commit

Permalink
revert "memcg: get rid of soft-limit tree infrastructure"
Browse files Browse the repository at this point in the history 
Revert commit e883110 ("memcg: get rid of soft-limit tree
infrastructure")

I merged this prematurely - Michal and Johannes still disagree about the
overall design direction and the future remains unclear.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  • Loading branch information
Andrew Morton authored and Linus Torvalds committed Sep 25, 2013
1 parent b1aff7f commit bb4cc1a
Showing 1 changed file with 263 additions and 2 deletions.
265 changes: 263 additions & 2 deletions mm/memcontrol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@
#include <linux/limits.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/swapops.h>
Expand Down Expand Up @@ -124,6 +125,7 @@ static const char * const mem_cgroup_lru_names[] = {
*/
enum mem_cgroup_events_target {
MEM_CGROUP_TARGET_THRESH,
MEM_CGROUP_TARGET_SOFTLIMIT,
MEM_CGROUP_TARGET_NUMAINFO,
MEM_CGROUP_NTARGETS,
};
Expand Down Expand Up @@ -159,6 +161,10 @@ struct mem_cgroup_per_zone {

struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];

struct rb_node tree_node; /* RB tree node */
unsigned long long usage_in_excess;/* Set to the value by which */
/* the soft limit is exceeded*/
bool on_tree;
struct mem_cgroup *memcg; /* Back pointer, we cannot */
/* use container_of */
};
Expand All @@ -167,6 +173,26 @@ struct mem_cgroup_per_node {
struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
};

/*
* Cgroups above their limits are maintained in a RB-Tree, independent of
* their hierarchy representation
*/

struct mem_cgroup_tree_per_zone {
struct rb_root rb_root;
spinlock_t lock;
};

struct mem_cgroup_tree_per_node {
struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
};

struct mem_cgroup_tree {
struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
};

static struct mem_cgroup_tree soft_limit_tree __read_mostly;

struct mem_cgroup_threshold {
struct eventfd_ctx *eventfd;
u64 threshold;
Expand Down Expand Up @@ -405,6 +431,7 @@ static bool move_file(void)
* limit reclaim to prevent infinite loops, if they ever occur.
*/
#define MEM_CGROUP_MAX_RECLAIM_LOOPS 100
#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2

enum charge_type {
MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
Expand Down Expand Up @@ -631,6 +658,164 @@ page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
return mem_cgroup_zoneinfo(memcg, nid, zid);
}

static struct mem_cgroup_tree_per_zone *
soft_limit_tree_node_zone(int nid, int zid)
{
return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
}

static struct mem_cgroup_tree_per_zone *
soft_limit_tree_from_page(struct page *page)
{
int nid = page_to_nid(page);
int zid = page_zonenum(page);

return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
}

static void
__mem_cgroup_insert_exceeded(struct mem_cgroup *memcg,
struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz,
unsigned long long new_usage_in_excess)
{
struct rb_node **p = &mctz->rb_root.rb_node;
struct rb_node *parent = NULL;
struct mem_cgroup_per_zone *mz_node;

if (mz->on_tree)
return;

mz->usage_in_excess = new_usage_in_excess;
if (!mz->usage_in_excess)
return;
while (*p) {
parent = *p;
mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
tree_node);
if (mz->usage_in_excess < mz_node->usage_in_excess)
p = &(*p)->rb_left;
/*
* We can't avoid mem cgroups that are over their soft
* limit by the same amount
*/
else if (mz->usage_in_excess >= mz_node->usage_in_excess)
p = &(*p)->rb_right;
}
rb_link_node(&mz->tree_node, parent, p);
rb_insert_color(&mz->tree_node, &mctz->rb_root);
mz->on_tree = true;
}

static void
__mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz)
{
if (!mz->on_tree)
return;
rb_erase(&mz->tree_node, &mctz->rb_root);
mz->on_tree = false;
}

static void
mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
struct mem_cgroup_per_zone *mz,
struct mem_cgroup_tree_per_zone *mctz)
{
spin_lock(&mctz->lock);
__mem_cgroup_remove_exceeded(memcg, mz, mctz);
spin_unlock(&mctz->lock);
}


static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
{
unsigned long long excess;
struct mem_cgroup_per_zone *mz;
struct mem_cgroup_tree_per_zone *mctz;
int nid = page_to_nid(page);
int zid = page_zonenum(page);
mctz = soft_limit_tree_from_page(page);

/*
* Necessary to update all ancestors when hierarchy is used.
* because their event counter is not touched.
*/
for (; memcg; memcg = parent_mem_cgroup(memcg)) {
mz = mem_cgroup_zoneinfo(memcg, nid, zid);
excess = res_counter_soft_limit_excess(&memcg->res);
/*
* We have to update the tree if mz is on RB-tree or
* mem is over its softlimit.
*/
if (excess || mz->on_tree) {
spin_lock(&mctz->lock);
/* if on-tree, remove it */
if (mz->on_tree)
__mem_cgroup_remove_exceeded(memcg, mz, mctz);
/*
* Insert again. mz->usage_in_excess will be updated.
* If excess is 0, no tree ops.
*/
__mem_cgroup_insert_exceeded(memcg, mz, mctz, excess);
spin_unlock(&mctz->lock);
}
}
}

static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
{
int node, zone;
struct mem_cgroup_per_zone *mz;
struct mem_cgroup_tree_per_zone *mctz;

for_each_node(node) {
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
mz = mem_cgroup_zoneinfo(memcg, node, zone);
mctz = soft_limit_tree_node_zone(node, zone);
mem_cgroup_remove_exceeded(memcg, mz, mctz);
}
}
}

static struct mem_cgroup_per_zone *
__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
{
struct rb_node *rightmost = NULL;
struct mem_cgroup_per_zone *mz;

retry:
mz = NULL;
rightmost = rb_last(&mctz->rb_root);
if (!rightmost)
goto done; /* Nothing to reclaim from */

mz = rb_entry(rightmost, struct mem_cgroup_per_zone, 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
* position in the tree.
*/
__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
!css_tryget(&mz->memcg->css))
goto retry;
done:
return mz;
}

static struct mem_cgroup_per_zone *
mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
{
struct mem_cgroup_per_zone *mz;

spin_lock(&mctz->lock);
mz = __mem_cgroup_largest_soft_limit_node(mctz);
spin_unlock(&mctz->lock);
return mz;
}

/*
* Implementation Note: reading percpu statistics for memcg.
*
Expand Down Expand Up @@ -789,6 +974,9 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
case MEM_CGROUP_TARGET_THRESH:
next = val + THRESHOLDS_EVENTS_TARGET;
break;
case MEM_CGROUP_TARGET_SOFTLIMIT:
next = val + SOFTLIMIT_EVENTS_TARGET;
break;
case MEM_CGROUP_TARGET_NUMAINFO:
next = val + NUMAINFO_EVENTS_TARGET;
break;
Expand All @@ -811,15 +999,20 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
/* threshold event is triggered in finer grain than soft limit */
if (unlikely(mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_THRESH))) {
bool do_softlimit;
bool do_numainfo __maybe_unused;

do_softlimit = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_SOFTLIMIT);
#if MAX_NUMNODES > 1
do_numainfo = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_NUMAINFO);
#endif
preempt_enable();

mem_cgroup_threshold(memcg);
if (unlikely(do_softlimit))
mem_cgroup_update_tree(memcg, page);
#if MAX_NUMNODES > 1
if (unlikely(do_numainfo))
atomic_inc(&memcg->numainfo_events);
Expand Down Expand Up @@ -1661,7 +1854,6 @@ static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg,
return total;
}

#if MAX_NUMNODES > 1
/**
* test_mem_cgroup_node_reclaimable
* @memcg: the target memcg
Expand All @@ -1684,6 +1876,7 @@ static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
return false;

}
#if MAX_NUMNODES > 1

/*
* Always updating the nodemask is not very good - even if we have an empty
Expand Down Expand Up @@ -1751,12 +1944,51 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
return node;
}

/*
* Check all nodes whether it contains reclaimable pages or not.
* For quick scan, we make use of scan_nodes. This will allow us to skip
* unused nodes. But scan_nodes is lazily updated and may not cotain
* enough new information. We need to do double check.
*/
static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
int nid;

/*
* quick check...making use of scan_node.
* We can skip unused nodes.
*/
if (!nodes_empty(memcg->scan_nodes)) {
for (nid = first_node(memcg->scan_nodes);
nid < MAX_NUMNODES;
nid = next_node(nid, memcg->scan_nodes)) {

if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
return true;
}
}
/*
* Check rest of nodes.
*/
for_each_node_state(nid, N_MEMORY) {
if (node_isset(nid, memcg->scan_nodes))
continue;
if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
return true;
}
return false;
}

#else
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
{
return 0;
}

static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
{
return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
}
#endif

/*
Expand Down Expand Up @@ -2692,7 +2924,9 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
unlock_page_cgroup(pc);

/*
* "charge_statistics" updated event counter.
* "charge_statistics" updated event counter. Then, check it.
* Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
* if they exceeds softlimit.
*/
memcg_check_events(memcg, page);
}
Expand Down Expand Up @@ -5791,6 +6025,8 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
mz = &pn->zoneinfo[zone];
lruvec_init(&mz->lruvec);
mz->usage_in_excess = 0;
mz->on_tree = false;
mz->memcg = memcg;
}
memcg->nodeinfo[node] = pn;
Expand Down Expand Up @@ -5846,6 +6082,7 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
int node;
size_t size = memcg_size();

mem_cgroup_remove_from_trees(memcg);
free_css_id(&mem_cgroup_subsys, &memcg->css);

for_each_node(node)
Expand Down Expand Up @@ -5882,6 +6119,29 @@ struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
}
EXPORT_SYMBOL(parent_mem_cgroup);

static void __init mem_cgroup_soft_limit_tree_init(void)
{
struct mem_cgroup_tree_per_node *rtpn;
struct mem_cgroup_tree_per_zone *rtpz;
int tmp, node, zone;

for_each_node(node) {
tmp = node;
if (!node_state(node, N_NORMAL_MEMORY))
tmp = -1;
rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
BUG_ON(!rtpn);

soft_limit_tree.rb_tree_per_node[node] = rtpn;

for (zone = 0; zone < MAX_NR_ZONES; zone++) {
rtpz = &rtpn->rb_tree_per_zone[zone];
rtpz->rb_root = RB_ROOT;
spin_lock_init(&rtpz->lock);
}
}
}

static struct cgroup_subsys_state * __ref
mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
{
Expand Down Expand Up @@ -6662,6 +6922,7 @@ static int __init mem_cgroup_init(void)
{
hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
enable_swap_cgroup();
mem_cgroup_soft_limit_tree_init();
memcg_stock_init();
return 0;
}
Expand Down

0 comments on commit bb4cc1a

Please sign in to comment.