On Tue 14-10-14 12:20:37, Johannes Weiner wrote:
> With charge reparenting, the last synchroneous stock drainer left.
>
> Signed-off-by: Johannes Weiner <han...@cmpxchg.org>
Acked-by: Michal Hocko <mho...@suse.cz>
> ---
> mm/memcontrol.c | 46 ++++++----------------------------------------
> 1 file changed, 6 insertions(+), 40 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index ce3ed7cc5c30..ac7d6cefcc63 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -634,8 +634,6 @@ static void disarm_static_keys(struct mem_cgroup *memcg)
> disarm_kmem_keys(memcg);
> }
>
> -static void drain_all_stock_async(struct mem_cgroup *memcg);
> -
> static struct mem_cgroup_per_zone *
> mem_cgroup_zone_zoneinfo(struct mem_cgroup *memcg, struct zone *zone)
> {
> @@ -2285,13 +2283,15 @@ static void refill_stock(struct mem_cgroup *memcg,
> unsigned int nr_pages)
>
> /*
> * Drains all per-CPU charge caches for given root_memcg resp. subtree
> - * of the hierarchy under it. sync flag says whether we should block
> - * until the work is done.
> + * of the hierarchy under it.
> */
> -static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
> +static void drain_all_stock(struct mem_cgroup *root_memcg)
> {
> int cpu, curcpu;
>
> + /* If someone's already draining, avoid adding running more workers. */
> + if (!mutex_trylock(&percpu_charge_mutex))
> + return;
> /* Notify other cpus that system-wide "drain" is running */
> get_online_cpus();
> curcpu = get_cpu();
> @@ -2312,41 +2312,7 @@ static void drain_all_stock(struct mem_cgroup
> *root_memcg, bool sync)
> }
> }
> put_cpu();
> -
> - if (!sync)
> - goto out;
> -
> - for_each_online_cpu(cpu) {
> - struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
> - if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
> - flush_work(&stock->work);
> - }
> -out:
> put_online_cpus();
> -}
> -
> -/*
> - * Tries to drain stocked charges in other cpus. This function is
> asynchronous
> - * and just put a work per cpu for draining localy on each cpu. Caller can
> - * expects some charges will be back later but cannot wait for it.
> - */
> -static void drain_all_stock_async(struct mem_cgroup *root_memcg)
> -{
> - /*
> - * If someone calls draining, avoid adding more kworker runs.
> - */
> - if (!mutex_trylock(&percpu_charge_mutex))
> - return;
> - drain_all_stock(root_memcg, false);
> - mutex_unlock(&percpu_charge_mutex);
> -}
> -
> -/* This is a synchronous drain interface. */
> -static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
> -{
> - /* called when force_empty is called */
> - mutex_lock(&percpu_charge_mutex);
> - drain_all_stock(root_memcg, true);
> mutex_unlock(&percpu_charge_mutex);
> }
>
> @@ -2455,7 +2421,7 @@ retry:
> goto retry;
>
> if (!drained) {
> - drain_all_stock_async(mem_over_limit);
> + drain_all_stock(mem_over_limit);
> drained = true;
> goto retry;
> }
> --
> 2.1.2
>
--
Michal Hocko
SUSE Labs
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