workqueue for memory cgroup asynchronous memory shrinker.
This patch implements the workqueue of async shrinker routine. each
memcg has a work and only one work can be scheduled at the same time.
If shrinking memory doesn't goes well, delay will be added to the work.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
mm/memcontrol.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 79 insertions(+), 3 deletions(-)
Index: mmotm-May6/mm/memcontrol.c
===================================================================
--- mmotm-May6.orig/mm/memcontrol.c
+++ mmotm-May6/mm/memcontrol.c
@@ -305,6 +305,12 @@ struct mem_cgroup {
* mem_cgroup ? And what type of charges should we move ?
*/
unsigned long move_charge_at_immigrate;
+
+ /* For asynchronous memory reclaim */
+ struct delayed_work async_work;
+ unsigned long async_work_flags;
+#define ASYNC_NORESCHED (0) /* need to stop scanning */
+#define ASYNC_RUNNING (1) /* a work is in schedule or running. */
/*
* percpu counter.
*/
@@ -3631,6 +3637,74 @@ unsigned long mem_cgroup_soft_limit_recl
return nr_reclaimed;
}
+struct workqueue_struct *memcg_async_shrinker;
+
+static int memcg_async_shrinker_init(void)
+{
+ memcg_async_shrinker = alloc_workqueue("memcg_async",
+ WQ_MEM_RECLAIM | WQ_UNBOUND | WQ_FREEZABLE, 0);
+ return 0;
+}
+module_init(memcg_async_shrinker_init);
+
+static void mem_cgroup_async_shrink(struct work_struct *work)
+{
+ struct delayed_work *dw = to_delayed_work(work);
+ struct mem_cgroup *mem = container_of(dw,
+ struct mem_cgroup, async_work);
+ bool congested = false;
+ int delay = 0;
+ unsigned long long required, usage, limit, shrink_to;
+
+ limit = res_counter_read_u64(&mem->res, RES_LIMIT);
+ shrink_to = limit - MEMCG_ASYNC_STOP_MARGIN - PAGE_SIZE;
+ usage = res_counter_read_u64(&mem->res, RES_USAGE);
+ if (shrink_to <= usage) {
+ required = usage - shrink_to;
+ required = (required >> PAGE_SHIFT) + 1;
+ /*
+ * This scans some number of pages and returns that memory
+ * reclaim was slow or now. If slow, we add a delay as
+ * congestion_wait() in vmscan.c
+ */
+ congested = mem_cgroup_shrink_static_scan(mem, (long)required);
+ }
+ if (test_bit(ASYNC_NORESCHED, &mem->async_work_flags)
+ || mem_cgroup_async_should_stop(mem))
+ goto finish_scan;
+ /* If memory reclaim couldn't go well, add delay */
+ if (congested)
+ delay = HZ/10;
+
+ if (queue_delayed_work(memcg_async_shrinker, &mem->async_work, delay))
+ return;
+finish_scan:
+ cgroup_release_and_wakeup_rmdir(&mem->css);
+ clear_bit(ASYNC_RUNNING, &mem->async_work_flags);
+ return;
+}
+
+static void run_mem_cgroup_async_shrinker(struct mem_cgroup *mem)
+{
+ if (test_bit(ASYNC_NORESCHED, &mem->async_work_flags))
+ return;
+ if (test_and_set_bit(ASYNC_RUNNING, &mem->async_work_flags))
+ return;
+ cgroup_exclude_rmdir(&mem->css);
+ if (!queue_delayed_work(memcg_async_shrinker, &mem->async_work, 0)) {
+ cgroup_release_and_wakeup_rmdir(&mem->css);
+ clear_bit(ASYNC_RUNNING, &mem->async_work_flags);
+ }
+ return;
+}
+
+static void stop_mem_cgroup_async_shrinker(struct mem_cgroup *mem)
+{
+ set_bit(ASYNC_NORESCHED, &mem->async_work_flags);
+ flush_delayed_work(&mem->async_work);
+ clear_bit(ASYNC_NORESCHED, &mem->async_work_flags);
+}
+
bool mem_cgroup_async_should_stop(struct mem_cgroup *mem)
{
return res_counter_margin(&mem->res) >= MEMCG_ASYNC_STOP_MARGIN;
@@ -3640,9 +3714,8 @@ static void mem_cgroup_may_async_reclaim
{
if (!mem->need_async_reclaim)
return;
- if (res_counter_margin(&mem->res) <= MEMCG_ASYNC_START_MARGIN) {
- /* Fill here */
- }
+ if (res_counter_margin(&mem->res) <= MEMCG_ASYNC_START_MARGIN)
+ run_mem_cgroup_async_shrinker(mem);
}
/*
@@ -3727,6 +3800,7 @@ move_account:
if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
goto out;
ret = -EINTR;
+ stop_mem_cgroup_async_shrinker(mem);
if (signal_pending(current))
goto out;
/* This is for making all *used* pages to be on LRU. */
@@ -4897,6 +4971,7 @@ mem_cgroup_create(struct cgroup_subsys *
mem->swappiness = mem_cgroup_swappiness(parent);
atomic_set(&mem->refcnt, 1);
mem->move_charge_at_immigrate = 0;
+ INIT_DELAYED_WORK(&mem->async_work, mem_cgroup_async_shrink);
mutex_init(&mem->thresholds_lock);
return &mem->css;
free_out:
--
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