On Fri, Apr 19, 2019 at 1:07 PM Roman Gushchin <guro@xxxxxx> wrote: > > On Thu, Apr 18, 2019 at 02:42:24PM -0700, Shakeel Butt wrote: > > The commit 475d0487a2ad ("mm: memcontrol: use per-cpu stocks for socket > > memory uncharging") added refill_stock() for skmem uncharging path to > > optimize workloads having high network traffic. Do the same for the kmem > > uncharging as well. However bypass the refill for offlined memcgs to not > > cause zombie apocalypse. > > > > Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> > > Hello, Shakeel! > > > --- > > mm/memcontrol.c | 17 ++++++++--------- > > 1 file changed, 8 insertions(+), 9 deletions(-) > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 2535e54e7989..7b8de091f572 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -178,6 +178,7 @@ struct mem_cgroup_event { > > > > static void mem_cgroup_threshold(struct mem_cgroup *memcg); > > static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); > > +static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages); > > > > /* Stuffs for move charges at task migration. */ > > /* > > @@ -2097,10 +2098,7 @@ static void drain_stock(struct memcg_stock_pcp *stock) > > struct mem_cgroup *old = stock->cached; > > > > if (stock->nr_pages) { > > - page_counter_uncharge(&old->memory, stock->nr_pages); > > - if (do_memsw_account()) > > - page_counter_uncharge(&old->memsw, stock->nr_pages); > > - css_put_many(&old->css, stock->nr_pages); > > + cancel_charge(old, stock->nr_pages); > > stock->nr_pages = 0; > > } > > stock->cached = NULL; > > @@ -2133,6 +2131,11 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) > > struct memcg_stock_pcp *stock; > > unsigned long flags; > > > > + if (unlikely(!mem_cgroup_online(memcg))) { > > + cancel_charge(memcg, nr_pages); > > + return; > > + } > > I'm slightly concerned about this part. Do we really need it? > The number of "zombies" which we can pin is limited by the number of CPUs, > and it will drop fast if there is any load on the machine. > > If we skip offline memcgs, it can slow down charging/uncharging of skmem, > which might be a problem, if the socket is in active use by an other cgroup. > Honestly, I'd drop this part. > Sure, I will wait for comments from others and then send the v2 without this. Shakeel