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 <hannes@cmpxchg.org> Acked-by: David Hildenbrand <david@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -964,6 +964,8 @@ Example output. You may not have all of these fields.
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Mlocked: 0 kB
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SwapTotal: 0 kB
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SwapFree: 0 kB
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Zswap: 1904 kB
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Zswapped: 7792 kB
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Dirty: 12 kB
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Writeback: 0 kB
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AnonPages: 4654780 kB
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@ -1055,6 +1057,10 @@ SwapTotal
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SwapFree
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Memory which has been evicted from RAM, and is temporarily
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on the disk
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Zswap
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Memory consumed by the zswap backend (compressed size)
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Zswapped
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Amount of anonymous memory stored in zswap (original size)
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Dirty
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Memory which is waiting to get written back to the disk
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Writeback
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@ -86,6 +86,13 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
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show_val_kb(m, "SwapTotal: ", i.totalswap);
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show_val_kb(m, "SwapFree: ", i.freeswap);
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#ifdef CONFIG_ZSWAP
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seq_printf(m, "Zswap: %8lu kB\n",
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(unsigned long)(zswap_pool_total_size >> 10));
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seq_printf(m, "Zswapped: %8lu kB\n",
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(unsigned long)atomic_read(&zswap_stored_pages) <<
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(PAGE_SHIFT - 10));
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#endif
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show_val_kb(m, "Dirty: ",
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global_node_page_state(NR_FILE_DIRTY));
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show_val_kb(m, "Writeback: ",
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@ -620,6 +620,11 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
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}
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#endif
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#ifdef CONFIG_ZSWAP
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extern u64 zswap_pool_total_size;
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extern atomic_t zswap_stored_pages;
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#endif
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#if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
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extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
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static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
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@ -136,6 +136,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
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#ifdef CONFIG_KSM
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COW_KSM,
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#endif
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#ifdef CONFIG_ZSWAP
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ZSWPIN,
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ZSWPOUT,
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#endif
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#ifdef CONFIG_X86
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DIRECT_MAP_LEVEL2_SPLIT,
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DIRECT_MAP_LEVEL3_SPLIT,
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@ -1396,6 +1396,10 @@ const char * const vmstat_text[] = {
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#ifdef CONFIG_KSM
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"cow_ksm",
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#endif
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#ifdef CONFIG_ZSWAP
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"zswpin",
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"zswpout",
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#endif
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#ifdef CONFIG_X86
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"direct_map_level2_splits",
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"direct_map_level3_splits",
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13
mm/zswap.c
13
mm/zswap.c
@ -42,9 +42,9 @@
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* statistics
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**********************************/
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/* Total bytes used by the compressed storage */
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static u64 zswap_pool_total_size;
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u64 zswap_pool_total_size;
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/* The number of compressed pages currently stored in zswap */
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static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
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atomic_t zswap_stored_pages = ATOMIC_INIT(0);
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/* The number of same-value filled pages currently stored in zswap */
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static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0);
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@ -1243,6 +1243,7 @@ insert_entry:
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/* update stats */
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atomic_inc(&zswap_stored_pages);
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zswap_update_total_size();
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count_vm_event(ZSWPOUT);
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return 0;
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@ -1285,11 +1286,10 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
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zswap_fill_page(dst, entry->value);
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kunmap_atomic(dst);
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ret = 0;
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goto freeentry;
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goto stats;
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}
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if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
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tmp = kmalloc(entry->length, GFP_ATOMIC);
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if (!tmp) {
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ret = -ENOMEM;
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@ -1304,10 +1304,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
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src += sizeof(struct zswap_header);
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if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
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memcpy(tmp, src, entry->length);
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src = tmp;
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zpool_unmap_handle(entry->pool->zpool, entry->handle);
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}
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@ -1326,7 +1324,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
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kfree(tmp);
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BUG_ON(ret);
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stats:
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count_vm_event(ZSWPIN);
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freeentry:
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spin_lock(&tree->lock);
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zswap_entry_put(tree, entry);
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