On Fri, Nov 18, 2022 at 10:24:05AM -0800, Nhat Pham wrote:
> This helps determines the coldest zspages as candidates for writeback.
>
> Signed-off-by: Nhat Pham <nphamcs@xxxxxxxxx>
> ---
> mm/zsmalloc.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 326faa751f0a..9e7b54324181 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -239,6 +239,11 @@ struct zs_pool {
> /* Compact classes */
> struct shrinker shrinker;
>
> +#ifdef CONFIG_ZPOOL
> + /* List tracking the zspages in LRU order by most recently added object */
> + struct list_head lru;
> +#endif
> +
> #ifdef CONFIG_ZSMALLOC_STAT
> struct dentry *stat_dentry;
> #endif
> @@ -260,6 +265,12 @@ struct zspage {
> unsigned int freeobj;
> struct page *first_page;
> struct list_head list; /* fullness list */
> +
> +#ifdef CONFIG_ZPOOL
> + /* links the zspage to the lru list in the pool */
> + struct list_head lru;
> +#endif
> +
> struct zs_pool *pool;
> #ifdef CONFIG_COMPACTION
> rwlock_t lock;
> @@ -352,6 +363,18 @@ static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage)
> kmem_cache_free(pool->zspage_cachep, zspage);
> }
>
> +#ifdef CONFIG_ZPOOL
> +/* Moves the zspage to the front of the zspool's LRU */
> +static void move_to_front(struct zs_pool *pool, struct zspage *zspage)
> +{
> + assert_spin_locked(&pool->lock);
> +
> + if (!list_empty(&zspage->lru))
> + list_del(&zspage->lru);
> + list_add(&zspage->lru, &pool->lru);
> +}
> +#endif
> +
> /* pool->lock(which owns the handle) synchronizes races */
> static void record_obj(unsigned long handle, unsigned long obj)
> {
> @@ -953,6 +976,9 @@ static void free_zspage(struct zs_pool *pool, struct size_class *class,
> }
>
> remove_zspage(class, zspage, ZS_EMPTY);
> +#ifdef CONFIG_ZPOOL
> + list_del(&zspage->lru);
> +#endif
> __free_zspage(pool, class, zspage);
> }
>
> @@ -998,6 +1024,10 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
> off %= PAGE_SIZE;
> }
>
> +#ifdef CONFIG_ZPOOL
> + INIT_LIST_HEAD(&zspage->lru);
> +#endif
> +
> set_freeobj(zspage, 0);
> }
>
> @@ -1418,9 +1448,8 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
> fix_fullness_group(class, zspage);
> record_obj(handle, obj);
> class_stat_inc(class, OBJ_USED, 1);
> - spin_unlock(&pool->lock);
>
> - return handle;
> + goto out;
> }
>
> spin_unlock(&pool->lock);
> @@ -1444,6 +1473,11 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
>
> /* We completely set up zspage so mark them as movable */
> SetZsPageMovable(pool, zspage);
> +out:
> +#ifdef CONFIG_ZPOOL
> + /* Move the zspage to front of pool's LRU */
> + move_to_front(pool, zspage);
> +#endif
> spin_unlock(&pool->lock);
Please move the move_to_front into zs_map_object with ZS_MM_WO with
comment with "why we are doing only for WO case".
