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 <[email protected]>
---
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
On Tue, Feb 09, 2021 at 09:46:43AM -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 <[email protected]>
> ---
> 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)
"Count" is not associated with xchg() semantics in my head, but I don't know
what's the better version. Maybe steal or pop?
Otherwise the patch looks good to me.
Thanks!
On Tue, Feb 9, 2021 at 5:27 PM Roman Gushchin <[email protected]> wrote:
>
> On Tue, Feb 09, 2021 at 09:46:43AM -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 <[email protected]>
> > ---
> > 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)
>
> "Count" is not associated with xchg() semantics in my head, but I don't know
> what's the better version. Maybe steal or pop?
It is used to retrieve the nr_deferred value. I don't think "steal" or
"pop" helps understand. Actually "count" is borrowed from
count_objects() method of shrinker.
>
> Otherwise the patch looks good to me.
>
> Thanks!
On Wed, Feb 10, 2021 at 6:37 AM Kirill Tkhai <[email protected]> wrote:
>
> On 10.02.2021 04:52, Yang Shi wrote:
> > On Tue, Feb 9, 2021 at 5:27 PM Roman Gushchin <[email protected]> wrote:
> >>
> >> On Tue, Feb 09, 2021 at 09:46:43AM -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 <[email protected]>
> >>> ---
> >>> 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)
> >>
> >> "Count" is not associated with xchg() semantics in my head, but I don't know
> >> what's the better version. Maybe steal or pop?
> >
> > It is used to retrieve the nr_deferred value. I don't think "steal" or
> > "pop" helps understand. Actually "count" is borrowed from
> > count_objects() method of shrinker.
>
> I'd also voted for another name.
>
> xchg_nr_deferred() or steal/pop sound better for me.
OK, I do have a hard time to understand steal/pop, but xchg sounds
more self-explained to me.
>