From: Nhat Pham <nphamcs@gmail.com>
To: akpm@linux-foundation.org
Cc: hannes@cmpxchg.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, minchan@kernel.org,
ngupta@vflare.org, senozhatsky@chromium.org, sjenning@redhat.com,
ddstreet@ieee.org, vitaly.wool@konsulko.com
Subject: [PATCH v7 4/6] zsmalloc: Add a LRU to zs_pool to keep track of zspages in LRU order
Date: Mon, 28 Nov 2022 11:16:13 -0800 [thread overview]
Message-ID: <20221128191616.1261026-5-nphamcs@gmail.com> (raw)
In-Reply-To: <20221128191616.1261026-1-nphamcs@gmail.com>
This helps determines the coldest zspages as candidates for writeback.
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
---
mm/zsmalloc.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 5427a00a0518..b1bc231d94a3 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;
@@ -953,6 +964,9 @@ 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 +1012,10 @@ 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);
}
@@ -1270,6 +1288,31 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
obj_to_location(obj, &page, &obj_idx);
zspage = get_zspage(page);
+#ifdef CONFIG_ZPOOL
+ /*
+ * Move the zspage to front of pool's LRU.
+ *
+ * Note that this is swap-specific, so by definition there are no ongoing
+ * accesses to the memory while the page is swapped out that would make
+ * it "hot". A new entry is hot, then ages to the tail until it gets either
+ * written back or swaps back in.
+ *
+ * Furthermore, map is also called during writeback. We must not put an
+ * isolated page on the LRU mid-reclaim.
+ *
+ * As a result, only update the LRU when the page is mapped for write
+ * when it's first instantiated.
+ *
+ * This is a deviation from the other backends, which perform this update
+ * in the allocation function (zbud_alloc, z3fold_alloc).
+ */
+ if (mm == ZS_MM_WO) {
+ if (!list_empty(&zspage->lru))
+ list_del(&zspage->lru);
+ list_add(&zspage->lru, &pool->lru);
+ }
+#endif
+
/*
* migration cannot move any zpages in this zspage. Here, pool->lock
* is too heavy since callers would take some time until they calls
@@ -1988,6 +2031,9 @@ static void async_free_zspage(struct work_struct *work)
VM_BUG_ON(fullness != ZS_EMPTY);
class = pool->size_class[class_idx];
spin_lock(&pool->lock);
+#ifdef CONFIG_ZPOOL
+ list_del(&zspage->lru);
+#endif
__free_zspage(pool, class, zspage);
spin_unlock(&pool->lock);
}
@@ -2299,6 +2345,10 @@ struct zs_pool *zs_create_pool(const char *name)
*/
zs_register_shrinker(pool);
+#ifdef CONFIG_ZPOOL
+ INIT_LIST_HEAD(&pool->lru);
+#endif
+
return pool;
err:
--
2.30.2
next prev parent reply other threads:[~2022-11-28 19:16 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-28 19:16 [PATCH v7 0/6] Implement writeback for zsmalloc Nhat Pham
2022-11-28 19:16 ` [PATCH v7 1/6] zswap: fix writeback lock ordering " Nhat Pham
2022-11-29 3:47 ` Sergey Senozhatsky
2022-11-28 19:16 ` [PATCH v7 2/6] zpool: clean out dead code Nhat Pham
2022-11-28 19:16 ` [PATCH v7 3/6] zsmalloc: Consolidate zs_pool's migrate_lock and size_class's locks Nhat Pham
2022-11-29 4:01 ` Sergey Senozhatsky
2022-11-28 19:16 ` Nhat Pham [this message]
2022-11-28 19:25 ` [PATCH v7 4/6] zsmalloc: Add a LRU to zs_pool to keep track of zspages in LRU order Johannes Weiner
2022-11-29 3:50 ` Sergey Senozhatsky
2022-11-29 11:53 ` Vitaly Wool
2022-11-29 14:03 ` Sergey Senozhatsky
2022-11-29 15:54 ` Johannes Weiner
2022-11-30 15:23 ` Vitaly Wool
2022-11-28 19:16 ` [PATCH v7 5/6] zsmalloc: Add zpool_ops field to zs_pool to store evict handlers Nhat Pham
2022-11-28 19:27 ` Johannes Weiner
2022-11-29 3:53 ` Sergey Senozhatsky
2022-11-28 19:16 ` [PATCH v7 6/6] zsmalloc: Implement writeback mechanism for zsmalloc Nhat Pham
2022-11-28 19:28 ` Johannes Weiner
2022-11-29 3:58 ` Sergey Senozhatsky
2023-01-03 4:57 ` [PATCH v7 0/6] Implement writeback " Thomas Weißschuh
2023-01-06 20:32 ` Nhat Pham
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