+CC zswap maintainers
On 8/19/21 21:55, Johannes Weiner wrote:
> 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);
>
