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Subject[v7 PATCH 09/12] mm: vmscan: use per memcg nr_deferred of shrinker
Date
Use per memcg's nr_deferred for memcg aware shrinkers.  The shrinker's nr_deferred
will be used in the following cases:
1. Non memcg aware shrinkers
2. !CONFIG_MEMCG
3. memcg is disabled by boot parameter

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
mm/vmscan.c | 78 ++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 66 insertions(+), 12 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index d4b030a0b2a9..748aa6e90f83 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -368,6 +368,24 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
up_write(&shrinker_rwsem);
}

+static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker,
+ struct mem_cgroup *memcg)
+{
+ struct shrinker_info *info;
+
+ info = shrinker_info_protected(memcg, nid);
+ return atomic_long_xchg(&info->nr_deferred[shrinker->id], 0);
+}
+
+static long add_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker,
+ struct mem_cgroup *memcg)
+{
+ struct shrinker_info *info;
+
+ info = shrinker_info_protected(memcg, nid);
+ return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]);
+}
+
static bool cgroup_reclaim(struct scan_control *sc)
{
return sc->target_mem_cgroup;
@@ -406,6 +424,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
{
}

+static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker,
+ struct mem_cgroup *memcg)
+{
+ return 0;
+}
+
+static long add_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker,
+ struct mem_cgroup *memcg)
+{
+ return 0;
+}
+
static bool cgroup_reclaim(struct scan_control *sc)
{
return false;
@@ -417,6 +447,39 @@ static bool writeback_throttling_sane(struct scan_control *sc)
}
#endif

+static long count_nr_deferred(struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ int nid = sc->nid;
+
+ if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+ nid = 0;
+
+ if (sc->memcg &&
+ (shrinker->flags & SHRINKER_MEMCG_AWARE))
+ return count_nr_deferred_memcg(nid, shrinker,
+ sc->memcg);
+
+ return atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
+}
+
+
+static long add_nr_deferred(long nr, struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ int nid = sc->nid;
+
+ if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+ nid = 0;
+
+ if (sc->memcg &&
+ (shrinker->flags & SHRINKER_MEMCG_AWARE))
+ return add_nr_deferred_memcg(nr, nid, shrinker,
+ sc->memcg);
+
+ return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]);
+}
+
/*
* This misses isolated pages which are not accounted for to save counters.
* As the data only determines if reclaim or compaction continues, it is
@@ -549,14 +612,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
long freeable;
long nr;
long new_nr;
- int nid = shrinkctl->nid;
long batch_size = shrinker->batch ? shrinker->batch
: SHRINK_BATCH;
long scanned = 0, next_deferred;

- if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
- nid = 0;
-
freeable = shrinker->count_objects(shrinker, shrinkctl);
if (freeable == 0 || freeable == SHRINK_EMPTY)
return freeable;
@@ -566,7 +625,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
* and zero it so that other concurrent shrinker invocations
* don't also do this scanning work.
*/
- nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
+ nr = count_nr_deferred(shrinker, shrinkctl);

total_scan = nr;
if (shrinker->seeks) {
@@ -657,14 +716,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
next_deferred = 0;
/*
* move the unused scan count back into the shrinker in a
- * manner that handles concurrent updates. If we exhausted the
- * scan, there is no need to do an update.
+ * manner that handles concurrent updates.
*/
- if (next_deferred > 0)
- new_nr = atomic_long_add_return(next_deferred,
- &shrinker->nr_deferred[nid]);
- else
- new_nr = atomic_long_read(&shrinker->nr_deferred[nid]);
+ new_nr = add_nr_deferred(next_deferred, shrinker, shrinkctl);

trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan);
return freed;
--
2.26.2
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