On Wed, Dec 02, 2020 at 10:27:22AM -0800, Yang Shi wrote:
> 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@xxxxxxxxx>
> ---
> mm/vmscan.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 82 insertions(+), 6 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index cba0bc8d4661..d569fdcaba79 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -203,6 +203,12 @@ static DECLARE_RWSEM(shrinker_rwsem);
> static DEFINE_IDR(shrinker_idr);
> static int shrinker_nr_max;
>
> +static inline bool is_deferred_memcg_aware(struct shrinker *shrinker)
> +{
> + return (shrinker->flags & SHRINKER_MEMCG_AWARE) &&
> + !mem_cgroup_disabled();
> +}
> +
> static int prealloc_memcg_shrinker(struct shrinker *shrinker)
> {
> int id, ret = -ENOMEM;
> @@ -271,7 +277,58 @@ static bool writeback_throttling_sane(struct scan_control *sc)
> #endif
> return false;
> }
> +
> +static inline long count_nr_deferred(struct shrinker *shrinker,
> + struct shrink_control *sc)
> +{
> + bool per_memcg_deferred = is_deferred_memcg_aware(shrinker) && sc->memcg;
> + struct memcg_shrinker_deferred *deferred;
> + struct mem_cgroup *memcg = sc->memcg;
> + int nid = sc->nid;
> + int id = shrinker->id;
> + long nr;
> +
> + if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
> + nid = 0;
> +
> + if (per_memcg_deferred) {
> + deferred = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_deferred,
> + true);
> + nr = atomic_long_xchg(&deferred->nr_deferred[id], 0);
> + } else
> + nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
> +
> + return nr;
> +}
> +
> +static inline long set_nr_deferred(long nr, struct shrinker *shrinker,
> + struct shrink_control *sc)
> +{
> + bool per_memcg_deferred = is_deferred_memcg_aware(shrinker) && sc->memcg;
> + struct memcg_shrinker_deferred *deferred;
> + struct mem_cgroup *memcg = sc->memcg;
> + int nid = sc->nid;
> + int id = shrinker->id;
> + long new_nr;
> +
> + if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
> + nid = 0;
> +
> + if (per_memcg_deferred) {
> + deferred = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_deferred,
> + true);
> + new_nr = atomic_long_add_return(nr, &deferred->nr_deferred[id]);
> + } else
> + new_nr = atomic_long_add_return(nr, &shrinker->nr_deferred[nid]);
> +
> + return new_nr;
> +}
> #else
> +static inline bool is_deferred_memcg_aware(struct shrinker *shrinker)
> +{
> + return false;
> +}
> +
> static int prealloc_memcg_shrinker(struct shrinker *shrinker)
> {
> return 0;
> @@ -290,6 +347,29 @@ static bool writeback_throttling_sane(struct scan_control *sc)
> {
> return true;
> }
> +
> +static inline long count_nr_deferred(struct shrinker *shrinker,
> + struct shrink_control *sc)
> +{
> + int nid = sc->nid;
> +
> + if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
> + nid = 0;
> +
> + return atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
> +}
> +
> +static inline long set_nr_deferred(long nr, struct shrinker *shrinker,
> + struct shrink_control *sc)
> +{
> + int nid = sc->nid;
> +
> + if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
> + nid = 0;
> +
> + return atomic_long_add_return(nr,
> + &shrinker->nr_deferred[nid]);
> +}
> #endif
>
> /*
> @@ -429,13 +509,10 @@ 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)
> @@ -446,7 +523,7 @@ 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) {
> @@ -539,8 +616,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
> * move the unused scan count back into the shrinker in a
> * manner that handles concurrent updates.
> */
> - new_nr = atomic_long_add_return(next_deferred,
> - &shrinker->nr_deferred[nid]);
> + new_nr = set_nr_deferred(next_deferred, shrinker, shrinkctl);
Ok, I think patch (1) can be just merged into this and then it would make total sense.
