mm: memcontrol: hook up vmpressure to socket pressure
Let the networking stack know when a memcg is under reclaim pressure so
that it can clamp its transmit windows accordingly.
Whenever the reclaim efficiency of a cgroup's LRU lists drops low enough
for a MEDIUM or HIGH vmpressure event to occur, assert a pressure state
in the socket and tcp memory code that tells it to curb consumption
growth from sockets associated with said control group.
Traditionally, vmpressure reports for the entire subtree of a memcg
under pressure, which drops useful information on the individual groups
reclaimed. However, it's too late to change the userinterface, so add a
second reporting mode that reports on the level of reclaim instead of at
the level of pressure, and use that report for sockets.
vmpressure events are naturally edge triggered, so for hysteresis assert
socket pressure for a second to allow for subsequent vmpressure events
to occur before letting the socket code return to normal.
This will likely need finetuning for a wider variety of workloads, but
for now stick to the vmpressure presets and keep hysteresis simple.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index c5afd57..506f03e 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -137,14 +137,11 @@
};
static bool vmpressure_event(struct vmpressure *vmpr,
- unsigned long scanned, unsigned long reclaimed)
+ enum vmpressure_levels level)
{
struct vmpressure_event *ev;
- enum vmpressure_levels level;
bool signalled = false;
- level = vmpressure_calc_level(scanned, reclaimed);
-
mutex_lock(&vmpr->events_lock);
list_for_each_entry(ev, &vmpr->events, node) {
@@ -164,6 +161,7 @@
struct vmpressure *vmpr = work_to_vmpressure(work);
unsigned long scanned;
unsigned long reclaimed;
+ enum vmpressure_levels level;
spin_lock(&vmpr->sr_lock);
/*
@@ -174,19 +172,21 @@
* here. No need for any locks here since we don't care if
* vmpr->reclaimed is in sync.
*/
- scanned = vmpr->scanned;
+ scanned = vmpr->tree_scanned;
if (!scanned) {
spin_unlock(&vmpr->sr_lock);
return;
}
- reclaimed = vmpr->reclaimed;
- vmpr->scanned = 0;
- vmpr->reclaimed = 0;
+ reclaimed = vmpr->tree_reclaimed;
+ vmpr->tree_scanned = 0;
+ vmpr->tree_reclaimed = 0;
spin_unlock(&vmpr->sr_lock);
+ level = vmpressure_calc_level(scanned, reclaimed);
+
do {
- if (vmpressure_event(vmpr, scanned, reclaimed))
+ if (vmpressure_event(vmpr, level))
break;
/*
* If not handled, propagate the event upward into the
@@ -199,6 +199,7 @@
* vmpressure() - Account memory pressure through scanned/reclaimed ratio
* @gfp: reclaimer's gfp mask
* @memcg: cgroup memory controller handle
+ * @tree: legacy subtree mode
* @scanned: number of pages scanned
* @reclaimed: number of pages reclaimed
*
@@ -206,9 +207,16 @@
* "instantaneous" memory pressure (scanned/reclaimed ratio). The raw
* pressure index is then further refined and averaged over time.
*
+ * If @tree is set, vmpressure is in traditional userspace reporting
+ * mode: @memcg is considered the pressure root and userspace is
+ * notified of the entire subtree's reclaim efficiency.
+ *
+ * If @tree is not set, reclaim efficiency is recorded for @memcg, and
+ * only in-kernel users are notified.
+ *
* This function does not return any value.
*/
-void vmpressure(gfp_t gfp, struct mem_cgroup *memcg,
+void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
unsigned long scanned, unsigned long reclaimed)
{
struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
@@ -238,15 +246,47 @@
if (!scanned)
return;
- spin_lock(&vmpr->sr_lock);
- vmpr->scanned += scanned;
- vmpr->reclaimed += reclaimed;
- scanned = vmpr->scanned;
- spin_unlock(&vmpr->sr_lock);
+ if (tree) {
+ spin_lock(&vmpr->sr_lock);
+ vmpr->tree_scanned += scanned;
+ vmpr->tree_reclaimed += reclaimed;
+ scanned = vmpr->scanned;
+ spin_unlock(&vmpr->sr_lock);
- if (scanned < vmpressure_win)
- return;
- schedule_work(&vmpr->work);
+ if (scanned < vmpressure_win)
+ return;
+ schedule_work(&vmpr->work);
+ } else {
+ enum vmpressure_levels level;
+
+ /* For now, no users for root-level efficiency */
+ if (memcg == root_mem_cgroup)
+ return;
+
+ spin_lock(&vmpr->sr_lock);
+ scanned = vmpr->scanned += scanned;
+ reclaimed = vmpr->reclaimed += reclaimed;
+ if (scanned < vmpressure_win) {
+ spin_unlock(&vmpr->sr_lock);
+ return;
+ }
+ vmpr->scanned = vmpr->reclaimed = 0;
+ spin_unlock(&vmpr->sr_lock);
+
+ level = vmpressure_calc_level(scanned, reclaimed);
+
+ if (level > VMPRESSURE_LOW) {
+ /*
+ * Let the socket buffer allocator know that
+ * we are having trouble reclaiming LRU pages.
+ *
+ * For hysteresis keep the pressure state
+ * asserted for a second in which subsequent
+ * pressure events can occur.
+ */
+ memcg->socket_pressure = jiffies + HZ;
+ }
+ }
}
/**
@@ -276,7 +316,7 @@
* to the vmpressure() basically means that we signal 'critical'
* level.
*/
- vmpressure(gfp, memcg, vmpressure_win, 0);
+ vmpressure(gfp, memcg, true, vmpressure_win, 0);
}
/**