From: chengming.zhou@linux.dev
To: cl@linux.com, penberg@kernel.org
Cc: rientjes@google.com, iamjoonsoo.kim@lge.com,
akpm@linux-foundation.org, vbabka@suse.cz,
roman.gushchin@linux.dev, 42.hyeyoo@gmail.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
chengming.zhou@linux.dev,
Chengming Zhou <zhouchengming@bytedance.com>
Subject: [RFC PATCH v3 7/7] slub: Optimize deactivate_slab()
Date: Tue, 24 Oct 2023 09:33:45 +0000 [thread overview]
Message-ID: <20231024093345.3676493-8-chengming.zhou@linux.dev> (raw)
In-Reply-To: <20231024093345.3676493-1-chengming.zhou@linux.dev>
From: Chengming Zhou <zhouchengming@bytedance.com>
Since the introduce of unfrozen slabs on cpu partial list, we don't
need to synchronize the slab frozen state under the node list_lock.
The caller of deactivate_slab() and the caller of __slab_free() won't
manipulate the slab list concurrently.
So we can get node list_lock in the last stage if we really need to
manipulate the slab list in this path.
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
mm/slub.c | 70 ++++++++++++++++++++-----------------------------------
1 file changed, 25 insertions(+), 45 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 486d44421432..64d550e415eb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2449,10 +2449,8 @@ static void init_kmem_cache_cpus(struct kmem_cache *s)
static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
void *freelist)
{
- enum slab_modes { M_NONE, M_PARTIAL, M_FREE, M_FULL_NOLIST };
struct kmem_cache_node *n = get_node(s, slab_nid(slab));
int free_delta = 0;
- enum slab_modes mode = M_NONE;
void *nextfree, *freelist_iter, *freelist_tail;
int tail = DEACTIVATE_TO_HEAD;
unsigned long flags = 0;
@@ -2499,58 +2497,40 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
* unfrozen and number of objects in the slab may have changed.
* Then release lock and retry cmpxchg again.
*/
-redo:
-
- old.freelist = READ_ONCE(slab->freelist);
- old.counters = READ_ONCE(slab->counters);
- VM_BUG_ON(!old.frozen);
-
- /* Determine target state of the slab */
- new.counters = old.counters;
- if (freelist_tail) {
- new.inuse -= free_delta;
- set_freepointer(s, freelist_tail, old.freelist);
- new.freelist = freelist;
- } else
- new.freelist = old.freelist;
+ do {
+ old.freelist = READ_ONCE(slab->freelist);
+ old.counters = READ_ONCE(slab->counters);
+ VM_BUG_ON(!old.frozen);
+
+ /* Determine target state of the slab */
+ new.counters = old.counters;
+ new.frozen = 0;
+ if (freelist_tail) {
+ new.inuse -= free_delta;
+ set_freepointer(s, freelist_tail, old.freelist);
+ new.freelist = freelist;
+ } else
+ new.freelist = old.freelist;
- new.frozen = 0;
+ } while (!slab_update_freelist(s, slab,
+ old.freelist, old.counters,
+ new.freelist, new.counters,
+ "unfreezing slab"));
+ /*
+ * Stage three: Manipulate the slab list based on the updated state.
+ */
if (!new.inuse && n->nr_partial >= s->min_partial) {
- mode = M_FREE;
+ stat(s, DEACTIVATE_EMPTY);
+ discard_slab(s, slab);
+ stat(s, FREE_SLAB);
} else if (new.freelist) {
- mode = M_PARTIAL;
- /*
- * Taking the spinlock removes the possibility that
- * acquire_slab() will see a slab that is frozen
- */
spin_lock_irqsave(&n->list_lock, flags);
- } else {
- mode = M_FULL_NOLIST;
- }
-
-
- if (!slab_update_freelist(s, slab,
- old.freelist, old.counters,
- new.freelist, new.counters,
- "unfreezing slab")) {
- if (mode == M_PARTIAL)
- spin_unlock_irqrestore(&n->list_lock, flags);
- goto redo;
- }
-
-
- if (mode == M_PARTIAL) {
add_partial(n, slab, tail);
spin_unlock_irqrestore(&n->list_lock, flags);
stat(s, tail);
- } else if (mode == M_FREE) {
- stat(s, DEACTIVATE_EMPTY);
- discard_slab(s, slab);
- stat(s, FREE_SLAB);
- } else if (mode == M_FULL_NOLIST) {
+ } else
stat(s, DEACTIVATE_FULL);
- }
}
#ifdef CONFIG_SLUB_CPU_PARTIAL
--
2.40.1
next prev parent reply other threads:[~2023-10-24 9:34 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-24 9:33 [RFC PATCH v3 0/7] slub: Delay freezing of CPU partial slabs chengming.zhou
2023-10-24 9:33 ` [RFC PATCH v3 1/7] slub: Keep track of whether slub is on the per-node partial list chengming.zhou
[not found] ` <6d054dbe-c90d-591d-11ca-b9ad3787683d@suse.cz>
2023-10-28 1:30 ` Chengming Zhou
2023-10-24 9:33 ` [RFC PATCH v3 2/7] slub: Prepare __slab_free() for unfrozen partial slab out of node " chengming.zhou
[not found] ` <43da5c9a-aeff-1bff-81a8-4611470c2514@suse.cz>
2023-10-28 1:35 ` Chengming Zhou
2023-10-24 9:33 ` [RFC PATCH v3 3/7] slub: Reflow ___slab_alloc() chengming.zhou
2023-10-24 9:33 ` [RFC PATCH v3 4/7] slub: Change get_partial() interfaces to return slab chengming.zhou
2023-10-30 16:55 ` Vlastimil Babka
2023-10-31 2:22 ` Chengming Zhou
2023-10-24 9:33 ` [RFC PATCH v3 5/7] slub: Introduce freeze_slab() chengming.zhou
2023-10-30 18:11 ` Vlastimil Babka
2023-10-24 9:33 ` [RFC PATCH v3 6/7] slub: Delay freezing of partial slabs chengming.zhou
2023-10-24 14:30 ` kernel test robot
2023-10-24 14:42 ` Chengming Zhou
2023-10-24 15:22 ` kernel test robot
2023-10-25 2:18 ` Chengming Zhou
2023-10-26 5:49 ` kernel test robot
2023-10-26 7:41 ` Chengming Zhou
2023-10-31 9:50 ` Vlastimil Babka
2023-10-24 9:33 ` chengming.zhou [this message]
2023-10-31 11:15 ` [RFC PATCH v3 7/7] slub: Optimize deactivate_slab() Vlastimil Babka
2023-10-31 11:41 ` Chengming Zhou
2023-10-27 17:57 ` [RFC PATCH v3 0/7] slub: Delay freezing of CPU partial slabs Christoph Lameter
2023-10-28 2:36 ` Chengming Zhou
2023-10-30 16:19 ` Vlastimil Babka
2023-10-31 2:29 ` Chengming Zhou
2023-10-30 19:25 ` Christoph Lameter
2023-10-31 2:50 ` Chengming Zhou
2023-10-31 3:47 ` Christoph Lameter
2023-10-31 4:57 ` Chengming Zhou
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