On Tue, Jun 14, 2022 at 3:26 PM Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote:
If we need to restrict toptier memory usage for a cgroup,
we need to retrieve usage of toptier memory efficiently.
Add a page counter to track toptier memory usage directly
so its value can be returned right away.
---
include/linux/memcontrol.h | 1 +
mm/memcontrol.c | 50 ++++++++++++++++++++++++++++++++------
2 files changed, 43 insertions(+), 8 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 9ecead1042b9..b4f727cba1de 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -241,6 +241,7 @@ struct mem_cgroup {
/* Accounted resources */
struct page_counter memory; /* Both v1 & v2 */
+ struct page_counter toptier;
union {
struct page_counter swap; /* v2 only */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2f6e95e6d200..2f20ec2712b8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -848,6 +848,23 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
}
+static inline void mem_cgroup_charge_toptier(struct mem_cgroup *memcg,
+ int nid,
+ int nr_pages)
+{
+ if (!node_is_toptier(nid) || !memcg)
+ return;
+
+ if (nr_pages >= 0) {
+ page_counter_charge(&memcg->toptier,
+ (unsigned long) nr_pages);
+ } else {
+ nr_pages = -nr_pages;
+ page_counter_uncharge(&memcg->toptier,
+ (unsigned long) nr_pages);
+ }
+}
+
When we don't know which pages are being charged, we should still charge the usage to toptier (assuming that toptier always include the default tier), e.g. from try_charge_memcg().
The idea is that when lower tier memory is not used, memcg->toptier and memcg->memory should have the same value. Otherwise, it can cause confusions about where the pages of (memcg->memory - memcg->toptier) go.
static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
enum mem_cgroup_events_target target)
{
@@ -3027,6 +3044,8 @@ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order)
if (!ret) {
page->memcg_data = (unsigned long)objcg |
MEMCG_DATA_KMEM;
+ mem_cgroup_charge_toptier(page_memcg(page),
+ page_to_nid(page), 1 << order);
return 0;
}
obj_cgroup_put(objcg);
@@ -3050,6 +3069,8 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
objcg = __folio_objcg(folio);
obj_cgroup_uncharge_pages(objcg, nr_pages);
+ mem_cgroup_charge_toptier(page_memcg(page),
+ page_to_nid(page), -nr_pages);
folio->memcg_data = 0;
obj_cgroup_put(objcg);
}
@@ -3947,13 +3968,10 @@ unsigned long mem_cgroup_memtier_usage(struct mem_cgroup *memcg,
unsigned long mem_cgroup_toptier_usage(struct mem_cgroup *memcg)
{
- struct memory_tier *top_tier;
-
- top_tier = list_first_entry(&memory_tiers, struct memory_tier, list);
- if (top_tier)
- return mem_cgroup_memtier_usage(memcg, top_tier);
- else
+ if (!memcg)
return 0;
+
+ return page_counter_read(&memcg->toptier);
}
#endif /* CONFIG_NUMA */
@@ -5228,11 +5246,13 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
memcg->oom_kill_disable = parent->oom_kill_disable;
page_counter_init(&memcg->memory, &parent->memory);
+ page_counter_init(&memcg->toptier, &parent->toptier);
page_counter_init(&memcg->swap, &parent->swap);
page_counter_init(&memcg->kmem, &parent->kmem);
page_counter_init(&memcg->tcpmem, &parent->tcpmem);
} else {
page_counter_init(&memcg->memory, NULL);
+ page_counter_init(&memcg->toptier, NULL);
page_counter_init(&memcg->swap, NULL);
page_counter_init(&memcg->kmem, NULL);
page_counter_init(&memcg->tcpmem, NULL);
@@ -5678,6 +5698,8 @@ static int mem_cgroup_move_account(struct page *page,
memcg_check_events(to, nid);
mem_cgroup_charge_statistics(from, -nr_pages);
memcg_check_events(from, nid);
+ mem_cgroup_charge_toptier(to, nid, nr_pages);
+ mem_cgroup_charge_toptier(from, nid, -nr_pages);
local_irq_enable();
out_unlock:
folio_unlock(folio);
@@ -6761,6 +6783,7 @@ static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg,
local_irq_disable();
mem_cgroup_charge_statistics(memcg, nr_pages);
+ mem_cgroup_charge_toptier(memcg, folio_nid(folio), nr_pages);
memcg_check_events(memcg, folio_nid(folio));
local_irq_enable();
out:
@@ -6853,6 +6876,7 @@ struct uncharge_gather {
unsigned long nr_memory;
unsigned long pgpgout;
unsigned long nr_kmem;
+ unsigned long nr_toptier;
int nid;
};
@@ -6867,6 +6891,7 @@ static void uncharge_batch(const struct uncharge_gather *ug)
if (ug->nr_memory) {
page_counter_uncharge(&ug->memcg->memory, ug->nr_memory);
+ page_counter_uncharge(&ug->memcg->toptier, ug->nr_toptier);
if (do_memsw_account())
page_counter_uncharge(&ug->memcg->memsw, ug->nr_memory);
if (ug->nr_kmem)
@@ -6929,12 +6954,18 @@ static void uncharge_folio(struct folio *folio, struct uncharge_gather *ug)
ug->nr_memory += nr_pages;
ug->nr_kmem += nr_pages;
+ if (node_is_toptier(folio_nid(folio)))
+ ug->nr_toptier += nr_pages;
+
folio->memcg_data = 0;
obj_cgroup_put(objcg);
} else {
/* LRU pages aren't accounted at the root level */
- if (!mem_cgroup_is_root(memcg))
+ if (!mem_cgroup_is_root(memcg)) {
ug->nr_memory += nr_pages;
+ if (node_is_toptier(folio_nid(folio)))
+ ug->nr_toptier += nr_pages;
+ }
ug->pgpgout++;
folio->memcg_data = 0;
@@ -7011,6 +7042,7 @@ void mem_cgroup_migrate(struct folio *old, struct folio *new)
/* Force-charge the new page. The old one will be freed soon */
if (!mem_cgroup_is_root(memcg)) {
page_counter_charge(&memcg->memory, nr_pages);
+ mem_cgroup_charge_toptier(memcg, folio_nid(new), nr_pages);
if (do_memsw_account())
page_counter_charge(&memcg->memsw, nr_pages);
}
@@ -7231,8 +7263,10 @@ void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
folio->memcg_data = 0;
- if (!mem_cgroup_is_root(memcg))
+ if (!mem_cgroup_is_root(memcg)) {
page_counter_uncharge(&memcg->memory, nr_entries);
+ mem_cgroup_charge_toptier(memcg, folio_nid(folio), -nr_entries);
+ }
if (!cgroup_memory_noswap && memcg != swap_memcg) {
if (!mem_cgroup_is_root(swap_memcg))
--
2.35.1
