Messages in this thread | | | Date | Sat, 24 Mar 2018 22:45:40 +0300 | From | Vladimir Davydov <> | Subject | Re: [PATCH 08/10] mm: Set bit in memcg shrinker bitmap on first list_lru item apearance |
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On Wed, Mar 21, 2018 at 04:22:40PM +0300, Kirill Tkhai wrote: > Introduce set_shrinker_bit() function to set shrinker-related > bit in memcg shrinker bitmap, and set the bit after the first > item is added and in case of reparenting destroyed memcg's items. > > This will allow next patch to make shrinkers be called only, > in case of they have charged objects at the moment, and > to improve shrink_slab() performance. > > Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> > --- > include/linux/shrinker.h | 7 +++++++ > mm/list_lru.c | 22 ++++++++++++++++++++-- > mm/vmscan.c | 7 +++++++ > 3 files changed, 34 insertions(+), 2 deletions(-) > > diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h > index 738de8ef5246..24aeed1bc332 100644 > --- a/include/linux/shrinker.h > +++ b/include/linux/shrinker.h > @@ -78,4 +78,11 @@ struct shrinker { > > extern __must_check int register_shrinker(struct shrinker *); > extern void unregister_shrinker(struct shrinker *); > +#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) > +extern void set_shrinker_bit(struct mem_cgroup *, int, int); > +#else > +static inline void set_shrinker_bit(struct mem_cgroup *memcg, int node, int id) > +{ > +} > +#endif
IMO this function, as well as other shrinker bitmap manipulation functions, should be defined in memcontrol.[hc] and have mem_cgroup_ prefix.
> diff --git a/mm/vmscan.c b/mm/vmscan.c > index 9d1df5d90eca..265cf069b470 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -378,6 +378,13 @@ static void del_shrinker(struct shrinker *shrinker) > list_del(&shrinker->list); > up_write(&shrinker_rwsem); > } > + > +void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int nr) > +{ > + struct shrinkers_map *map = SHRINKERS_MAP(memcg); > + > + set_bit(nr, map->map[nid]); > +}
Shouldn't we use rcu_read_lock here? After all, the map can be reallocated right from under our feet.
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