When a system is under memory pressure, it may be beneficial to prioritize
some memory cgroups to keep their pages resident ahead of other cgroups'
pages. Add a new interface to memory cgroups, memory.priority, that enables
kswapd and direct reclaim to scan more pages in lower-priority cgroups
before looking at higher-priority cgroups.
Signed-off-by: Tim Murray <timmurray@xxxxxxxxxx>
---
include/linux/memcontrol.h | 20 +++++++++++++++++++-
mm/memcontrol.c | 33 +++++++++++++++++++++++++++++++++
mm/vmscan.c | 3 ++-
3 files changed, 54 insertions(+), 2 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 5af377303880..0d0f95839a8d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -206,7 +206,9 @@ struct mem_cgroup {
bool oom_lock;
int under_oom;
- int swappiness;
+ int swappiness;
+ int priority;
+
/* OOM-Killer disable */
int oom_kill_disable;
@@ -487,6 +489,16 @@ static inline bool task_in_memcg_oom(struct task_struct *p)
bool mem_cgroup_oom_synchronize(bool wait);
+static inline int mem_cgroup_priority(struct mem_cgroup *memcg)
+{
+ /* root ? */
+ if (mem_cgroup_disabled() || !memcg->css.parent)
+ return 0;
+
+ return memcg->priority;
+}
+
+
#ifdef CONFIG_MEMCG_SWAP
extern int do_swap_account;
#endif
@@ -766,6 +778,12 @@ static inline
void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
{
}
+
+static inline int mem_cgroup_priority(struct mem_cgroup *memcg)
+{
+ return 0;
+}
+
#endif /* CONFIG_MEMCG */
#ifdef CONFIG_CGROUP_WRITEBACK
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2bd7541d7c11..7343ca106a36 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -81,6 +81,8 @@ struct mem_cgroup *root_mem_cgroup __read_mostly;
#define MEM_CGROUP_RECLAIM_RETRIES 5
+#define MEM_CGROUP_PRIORITY_MAX 10
+
/* Socket memory accounting disabled? */
static bool cgroup_memory_nosocket;
@@ -241,6 +243,7 @@ enum res_type {
_OOM_TYPE,
_KMEM,
_TCP,
+ _PRIO,
};
#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val))
@@ -842,6 +845,10 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
*/
memcg = mem_cgroup_from_css(css);
+ if (reclaim && reclaim->priority &&
+ (DEF_PRIORITY - memcg->priority) < reclaim->priority)
+ continue;
+
if (css == &root->css)
break;
@@ -2773,6 +2780,7 @@ enum {
RES_MAX_USAGE,
RES_FAILCNT,
RES_SOFT_LIMIT,
+ RES_PRIORITY,
};
static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
@@ -2783,6 +2791,7 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
switch (MEMFILE_TYPE(cft->private)) {
case _MEM:
+ case _PRIO:
counter = &memcg->memory;
break;
case _MEMSWAP:
@@ -2813,6 +2822,8 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
return counter->failcnt;
case RES_SOFT_LIMIT:
return (u64)memcg->soft_limit * PAGE_SIZE;
+ case RES_PRIORITY:
+ return (u64)memcg->priority;
default:
BUG();
}
@@ -2966,6 +2977,22 @@ static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
return ret;
}
+static ssize_t mem_cgroup_update_prio(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ unsigned long long prio = -1;
+
+ buf = strstrip(buf);
+ prio = memparse(buf, NULL);
+
+ if (prio >= 0 && prio <= MEM_CGROUP_PRIORITY_MAX) {
+ memcg->priority = (int)prio;
+ return nbytes;
+ }
+ return -EINVAL;
+}
+
/*
* The user of this function is...
* RES_LIMIT.
@@ -3940,6 +3967,12 @@ static struct cftype mem_cgroup_legacy_files[] = {
.read_u64 = mem_cgroup_read_u64,
},
{
+ .name = "priority",
+ .private = MEMFILE_PRIVATE(_PRIO, RES_PRIORITY),
+ .write = mem_cgroup_update_prio,
+ .read_u64 = mem_cgroup_read_u64,
+ },
+ {
.name = "stat",
.seq_show = memcg_stat_show,
},
diff --git a/mm/vmscan.c b/mm/vmscan.c
index bc8031ef994d..c47b21326ab0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2116,6 +2116,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
unsigned long *lru_pages)
{
int swappiness = mem_cgroup_swappiness(memcg);
+ int priority = mem_cgroup_priority(memcg);
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
u64 fraction[2];
u64 denominator = 0; /* gcc */
@@ -2287,7 +2288,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
unsigned long scan;
size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
- scan = size >> sc->priority;
+ scan = size >> (sc->priority + priority);
if (!scan && pass && force_scan)
scan = min(size, SWAP_CLUSTER_MAX);
--
2.12.0.367.g23dc2f6d3c-goog
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