Currently it requires poking at debugfs to figure out the size of the
zswap cache size on a host. There are no counters for reads and writes
against the cache. This makes it difficult to understand behavior on
production systems.
Print zswap memory consumption in /proc/meminfo, count zswapouts and
zswapins in /proc/vmstat.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
fs/proc/meminfo.c | 4 ++++
include/linux/swap.h | 4 ++++
include/linux/vm_event_item.h | 4 ++++
mm/vmstat.c | 4 ++++
mm/zswap.c | 11 +++++------
5 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 6fa761c9cc78..2dc474940691 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -86,6 +86,10 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
show_val_kb(m, "SwapTotal: ", i.totalswap);
show_val_kb(m, "SwapFree: ", i.freeswap);
+#ifdef CONFIG_ZSWAP
+ seq_printf(m, "Zswap: %8lu kB\n",
+ (unsigned long)(zswap_pool_total_size >> 10));
+#endif
show_val_kb(m, "Dirty: ",
global_node_page_state(NR_FILE_DIRTY));
show_val_kb(m, "Writeback: ",
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 144727041e78..3b23c88b6a8d 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -696,6 +696,10 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
}
#endif
+#ifdef CONFIG_ZSWAP
+extern u64 zswap_pool_total_size;
+#endif
+
#if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
extern void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
#else
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index ae0dd1948c2b..9dbebea09c69 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -125,6 +125,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
SWAP_RA,
SWAP_RA_HIT,
#endif
+#ifdef CONFIG_ZSWAP
+ ZSWPIN,
+ ZSWPOUT,
+#endif
#ifdef CONFIG_X86
DIRECT_MAP_LEVEL2_SPLIT,
DIRECT_MAP_LEVEL3_SPLIT,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index cccee36b289c..31aada15c571 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1369,6 +1369,10 @@ const char * const vmstat_text[] = {
"swap_ra",
"swap_ra_hit",
#endif
+#ifdef CONFIG_ZSWAP
+ "zswpin",
+ "zswpout",
+#endif
#ifdef CONFIG_X86
"direct_map_level2_splits",
"direct_map_level3_splits",
diff --git a/mm/zswap.c b/mm/zswap.c
index 20763267a219..f93a7c715f76 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -40,7 +40,7 @@
* statistics
**********************************/
/* Total bytes used by the compressed storage */
-static u64 zswap_pool_total_size;
+u64 zswap_pool_total_size;
/* The number of compressed pages currently stored in zswap */
static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
/* The number of same-value filled pages currently stored in zswap */
@@ -1231,6 +1231,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
/* update stats */
atomic_inc(&zswap_stored_pages);
zswap_update_total_size();
+ count_vm_event(ZSWAPOUT);
return 0;
@@ -1273,11 +1274,10 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
zswap_fill_page(dst, entry->value);
kunmap_atomic(dst);
ret = 0;
- goto freeentry;
+ goto stats;
}
if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
-
tmp = kmalloc(entry->length, GFP_ATOMIC);
if (!tmp) {
ret = -ENOMEM;
@@ -1292,10 +1292,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
src += sizeof(struct zswap_header);
if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
-
memcpy(tmp, src, entry->length);
src = tmp;
-
zpool_unmap_handle(entry->pool->zpool, entry->handle);
}
@@ -1314,7 +1312,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
kfree(tmp);
BUG_ON(ret);
-
+stats:
+ count_vm_event(ZSWAPIN);
freeentry:
spin_lock(&tree->lock);
zswap_entry_put(tree, entry);
--
2.32.0
