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authorAndrew Morton <akpm@linux-foundation.org>2013-09-24 15:27:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-24 17:00:26 -0700
commit0608f43da64a1f1c42507304b5f25bc8b1227aa4 (patch)
tree3138a251439bee1f12bd176f41f3fc63e194f455 /mm
parentbb4cc1a8b5eaf3b9e5707d7c270400b05d11a2b7 (diff)
downloadlinux-stericsson-0608f43da64a1f1c42507304b5f25bc8b1227aa4.tar.gz
revert "memcg, vmscan: integrate soft reclaim tighter with zone shrinking code"
Revert commit 3b38722efd9f ("memcg, vmscan: integrate soft reclaim tighter with zone shrinking code") 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>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c163
-rw-r--r--mm/vmscan.c62
2 files changed, 168 insertions, 57 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 852dbec07ce6..1c52ddbc839b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1991,28 +1991,57 @@ static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
}
#endif
-/*
- * A group is eligible for the soft limit reclaim if
- * a) it is over its soft limit
- * b) any parent up the hierarchy is over its soft limit
- */
-bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg)
-{
- struct mem_cgroup *parent = memcg;
-
- if (res_counter_soft_limit_excess(&memcg->res))
- return true;
-
- /*
- * If any parent up the hierarchy is over its soft limit then we
- * have to obey and reclaim from this group as well.
- */
- while ((parent = parent_mem_cgroup(parent))) {
- if (res_counter_soft_limit_excess(&parent->res))
- return true;
+static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
+ struct zone *zone,
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
+{
+ struct mem_cgroup *victim = NULL;
+ int total = 0;
+ int loop = 0;
+ unsigned long excess;
+ unsigned long nr_scanned;
+ struct mem_cgroup_reclaim_cookie reclaim = {
+ .zone = zone,
+ .priority = 0,
+ };
+
+ excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
+
+ while (1) {
+ victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
+ if (!victim) {
+ loop++;
+ if (loop >= 2) {
+ /*
+ * If we have not been able to reclaim
+ * anything, it might because there are
+ * no reclaimable pages under this hierarchy
+ */
+ if (!total)
+ break;
+ /*
+ * We want to do more targeted reclaim.
+ * excess >> 2 is not to excessive so as to
+ * reclaim too much, nor too less that we keep
+ * coming back to reclaim from this cgroup
+ */
+ if (total >= (excess >> 2) ||
+ (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
+ break;
+ }
+ continue;
+ }
+ if (!mem_cgroup_reclaimable(victim, false))
+ continue;
+ total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
+ zone, &nr_scanned);
+ *total_scanned += nr_scanned;
+ if (!res_counter_soft_limit_excess(&root_memcg->res))
+ break;
}
-
- return false;
+ mem_cgroup_iter_break(root_memcg, victim);
+ return total;
}
static DEFINE_SPINLOCK(memcg_oom_lock);
@@ -4761,6 +4790,98 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
return ret;
}
+unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
+ gfp_t gfp_mask,
+ unsigned long *total_scanned)
+{
+ unsigned long nr_reclaimed = 0;
+ struct mem_cgroup_per_zone *mz, *next_mz = NULL;
+ unsigned long reclaimed;
+ int loop = 0;
+ struct mem_cgroup_tree_per_zone *mctz;
+ unsigned long long excess;
+ unsigned long nr_scanned;
+
+ if (order > 0)
+ return 0;
+
+ mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
+ /*
+ * This loop can run a while, specially if mem_cgroup's continuously
+ * keep exceeding their soft limit and putting the system under
+ * pressure
+ */
+ do {
+ if (next_mz)
+ mz = next_mz;
+ else
+ mz = mem_cgroup_largest_soft_limit_node(mctz);
+ if (!mz)
+ break;
+
+ nr_scanned = 0;
+ reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone,
+ gfp_mask, &nr_scanned);
+ nr_reclaimed += reclaimed;
+ *total_scanned += nr_scanned;
+ spin_lock(&mctz->lock);
+
+ /*
+ * If we failed to reclaim anything from this memory cgroup
+ * it is time to move on to the next cgroup
+ */
+ next_mz = NULL;
+ if (!reclaimed) {
+ do {
+ /*
+ * Loop until we find yet another one.
+ *
+ * By the time we get the soft_limit lock
+ * again, someone might have aded the
+ * group back on the RB tree. Iterate to
+ * make sure we get a different mem.
+ * mem_cgroup_largest_soft_limit_node returns
+ * NULL if no other cgroup is present on
+ * the tree
+ */
+ next_mz =
+ __mem_cgroup_largest_soft_limit_node(mctz);
+ if (next_mz == mz)
+ css_put(&next_mz->memcg->css);
+ else /* next_mz == NULL or other memcg */
+ break;
+ } while (1);
+ }
+ __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
+ excess = res_counter_soft_limit_excess(&mz->memcg->res);
+ /*
+ * One school of thought says that we should not add
+ * back the node to the tree if reclaim returns 0.
+ * But our reclaim could return 0, simply because due
+ * to priority we are exposing a smaller subset of
+ * memory to reclaim from. Consider this as a longer
+ * term TODO.
+ */
+ /* If excess == 0, no tree ops */
+ __mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess);
+ spin_unlock(&mctz->lock);
+ css_put(&mz->memcg->css);
+ loop++;
+ /*
+ * Could not reclaim anything and there are no more
+ * mem cgroups to try or we seem to be looping without
+ * reclaiming anything.
+ */
+ if (!nr_reclaimed &&
+ (next_mz == NULL ||
+ loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
+ break;
+ } while (!nr_reclaimed);
+ if (next_mz)
+ css_put(&next_mz->memcg->css);
+ return nr_reclaimed;
+}
+
/**
* mem_cgroup_force_empty_list - clears LRU of a group
* @memcg: group to clear
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0e081cada4ba..beb35778c69f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -139,21 +139,11 @@ static bool global_reclaim(struct scan_control *sc)
{
return !sc->target_mem_cgroup;
}
-
-static bool mem_cgroup_should_soft_reclaim(struct scan_control *sc)
-{
- return !mem_cgroup_disabled() && global_reclaim(sc);
-}
#else
static bool global_reclaim(struct scan_control *sc)
{
return true;
}
-
-static bool mem_cgroup_should_soft_reclaim(struct scan_control *sc)
-{
- return false;
-}
#endif
unsigned long zone_reclaimable_pages(struct zone *zone)
@@ -2174,8 +2164,7 @@ static inline bool should_continue_reclaim(struct zone *zone,
}
}
-static void
-__shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
+static void shrink_zone(struct zone *zone, struct scan_control *sc)
{
unsigned long nr_reclaimed, nr_scanned;
@@ -2194,12 +2183,6 @@ __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
do {
struct lruvec *lruvec;
- if (soft_reclaim &&
- !mem_cgroup_soft_reclaim_eligible(memcg)) {
- memcg = mem_cgroup_iter(root, memcg, &reclaim);
- continue;
- }
-
lruvec = mem_cgroup_zone_lruvec(zone, memcg);
shrink_lruvec(lruvec, sc);
@@ -2230,24 +2213,6 @@ __shrink_zone(struct zone *zone, struct scan_control *sc, bool soft_reclaim)
sc->nr_scanned - nr_scanned, sc));
}
-
-static void shrink_zone(struct zone *zone, struct scan_control *sc)
-{
- bool do_soft_reclaim = mem_cgroup_should_soft_reclaim(sc);
- unsigned long nr_scanned = sc->nr_scanned;
-
- __shrink_zone(zone, sc, do_soft_reclaim);
-
- /*
- * No group is over the soft limit or those that are do not have
- * pages in the zone we are reclaiming so we have to reclaim everybody
- */
- if (do_soft_reclaim && (sc->nr_scanned == nr_scanned)) {
- __shrink_zone(zone, sc, false);
- return;
- }
-}
-
/* Returns true if compaction should go ahead for a high-order request */
static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
{
@@ -2309,6 +2274,8 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
{
struct zoneref *z;
struct zone *zone;
+ unsigned long nr_soft_reclaimed;
+ unsigned long nr_soft_scanned;
bool aborted_reclaim = false;
/*
@@ -2348,6 +2315,18 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
continue;
}
}
+ /*
+ * This steals pages from memory cgroups over softlimit
+ * and returns the number of reclaimed pages and
+ * scanned pages. This works for global memory pressure
+ * and balancing, not for a memcg's limit.
+ */
+ nr_soft_scanned = 0;
+ nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+ sc->order, sc->gfp_mask,
+ &nr_soft_scanned);
+ sc->nr_reclaimed += nr_soft_reclaimed;
+ sc->nr_scanned += nr_soft_scanned;
/* need some check for avoid more shrink_zone() */
}
@@ -2941,6 +2920,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
{
int i;
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
+ unsigned long nr_soft_reclaimed;
+ unsigned long nr_soft_scanned;
struct scan_control sc = {
.gfp_mask = GFP_KERNEL,
.priority = DEF_PRIORITY,
@@ -3055,6 +3036,15 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
sc.nr_scanned = 0;
+ nr_soft_scanned = 0;
+ /*
+ * Call soft limit reclaim before calling shrink_zone.
+ */
+ nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+ order, sc.gfp_mask,
+ &nr_soft_scanned);
+ sc.nr_reclaimed += nr_soft_reclaimed;
+
/*
* There should be no need to raise the scanning
* priority if enough pages are already being scanned