From f6498b776d280b30a4614d8261840961e993c2c8 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Thu, 19 May 2022 14:08:53 -0700 Subject: mm: zswap: add basic meminfo and vmstat coverage Currently it requires poking at debugfs to figure out the size and population of the zswap cache on a host. There are no counters for reads and writes against the cache. As a result, it's difficult to understand zswap behavior on production systems. Print zswap memory consumption and how many pages are zswapped out in /proc/meminfo. Count zswapouts and zswapins in /proc/vmstat. Link: https://lkml.kernel.org/r/20220510152847.230957-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: David Hildenbrand Cc: Dan Streetman Cc: Michal Hocko Cc: Minchan Kim Cc: Roman Gushchin Cc: Seth Jennings Cc: Shakeel Butt Signed-off-by: Andrew Morton --- Documentation/filesystems/proc.rst | 6 ++++++ fs/proc/meminfo.c | 7 +++++++ include/linux/swap.h | 5 +++++ include/linux/vm_event_item.h | 4 ++++ mm/vmstat.c | 4 ++++ mm/zswap.c | 13 ++++++------- 6 files changed, 32 insertions(+), 7 deletions(-) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 5e9791457876..cfec3cab0f9a 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -964,6 +964,8 @@ Example output. You may not have all of these fields. Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB + Zswap: 1904 kB + Zswapped: 7792 kB Dirty: 12 kB Writeback: 0 kB AnonPages: 4654780 kB @@ -1055,6 +1057,10 @@ SwapTotal SwapFree Memory which has been evicted from RAM, and is temporarily on the disk +Zswap + Memory consumed by the zswap backend (compressed size) +Zswapped + Amount of anonymous memory stored in zswap (original size) Dirty Memory which is waiting to get written back to the disk Writeback diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c index 6fa761c9cc78..6e89f0e2fd20 100644 --- a/fs/proc/meminfo.c +++ b/fs/proc/meminfo.c @@ -86,6 +86,13 @@ 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)); + seq_printf(m, "Zswapped: %8lu kB\n", + (unsigned long)atomic_read(&zswap_stored_pages) << + (PAGE_SHIFT - 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 04c0713c1d6e..f3ae17b43f20 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -620,6 +620,11 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) } #endif +#ifdef CONFIG_ZSWAP +extern u64 zswap_pool_total_size; +extern atomic_t zswap_stored_pages; +#endif + #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask); static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index e83967e4c20e..404024486fa5 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -136,6 +136,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, #ifdef CONFIG_KSM COW_KSM, #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 b94a2e4723ff..da525bfb6f4a 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1396,6 +1396,10 @@ const char * const vmstat_text[] = { #ifdef CONFIG_KSM "cow_ksm", #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 2c5db4cbedea..e3c16a70f533 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -42,9 +42,9 @@ * 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); +atomic_t zswap_stored_pages = ATOMIC_INIT(0); /* The number of same-value filled pages currently stored in zswap */ static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0); @@ -1243,6 +1243,7 @@ insert_entry: /* update stats */ atomic_inc(&zswap_stored_pages); zswap_update_total_size(); + count_vm_event(ZSWPOUT); return 0; @@ -1285,11 +1286,10 @@ 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; @@ -1304,10 +1304,8 @@ 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); } @@ -1326,7 +1324,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, kfree(tmp); BUG_ON(ret); - +stats: + count_vm_event(ZSWPIN); freeentry: spin_lock(&tree->lock); zswap_entry_put(tree, entry); -- cgit v1.2.3