[PATCH v6 4/6] mm: memcg: add per-memcg zswap writeback stat

Nhat Pham
2023-11-27T19:37:08Z

From: Domenico Cerasuolo <cerasuolodomenico@gmail.com>

Since zswap now writes back pages from memcg-specific LRUs, we now need a
new stat to show writebacks count for each memcg.

Suggested-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
---
include/linux/vm_event_item.h | 1 +
mm/memcontrol.c | 1 +
mm/vmstat.c | 1 +
mm/zswap.c | 3 +++
4 files changed, 6 insertions(+)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index d1b847502f09..f4569ad98edf 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -142,6 +142,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
#ifdef CONFIG_ZSWAP
ZSWPIN,
ZSWPOUT,
+ ZSWP_WB,
#endif
#ifdef CONFIG_X86
DIRECT_MAP_LEVEL2_SPLIT,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0399aec8c0e3..a82f9c695c6c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -703,6 +703,7 @@ static const unsigned int memcg_vm_event_stat[] = {
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
ZSWPIN,
ZSWPOUT,
+ ZSWP_WB,
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
THP_FAULT_ALLOC,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index afa5a38fcc9c..2249f85e4a87 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1401,6 +1401,7 @@ const char * const vmstat_text[] = {
#ifdef CONFIG_ZSWAP
"zswpin",
"zswpout",
+ "zswp_wb",
#endif
#ifdef CONFIG_X86
"direct_map_level2_splits",
diff --git a/mm/zswap.c b/mm/zswap.c
index e441cbcab9a9..9f5142524d48 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -754,6 +754,9 @@ static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_o
}
zswap_written_back_pages++;

+ if (entry->objcg)
+ count_objcg_event(entry->objcg, ZSWP_WB);
+
/*
* Writeback started successfully, the page now belongs to the
* swapcache. Drop the entry from zswap - unless invalidate already
--
2.34.1