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 3/5] slub: Optimize deactivate_slab()
Date: Tue, 17 Oct 2023 15:44:37 +0000 [thread overview]
Message-ID: <20231017154439.3036608-4-chengming.zhou@linux.dev> (raw)
In-Reply-To: <20231017154439.3036608-1-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 stage three if we 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 27eac93baa13..5a9711b35c74 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2520,10 +2520,8 @@ 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;
@@ -2570,58 +2568,40 @@ 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:[~2023-10-17 15:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-17 15:44 [RFC PATCH 0/5] slub: Delay freezing of CPU partial slabs chengming.zhou
2023-10-17 15:44 ` [RFC PATCH 1/5] slub: Introduce on_partial() chengming.zhou
2023-10-17 15:54 ` Matthew Wilcox
2023-10-18 7:37 ` Chengming Zhou
2023-10-27 5:26 ` kernel test robot
2023-10-27 9:43 ` Chengming Zhou
2023-10-17 15:44 ` [RFC PATCH 2/5] slub: Don't manipulate slab list when used by cpu chengming.zhou
2023-10-17 15:44 ` chengming.zhou [this message]
2023-10-17 15:44 ` [RFC PATCH 4/5] slub: Don't freeze slabs for cpu partial chengming.zhou
2023-10-17 15:44 ` [RFC PATCH 5/5] slub: Introduce get_cpu_partial() chengming.zhou
2023-10-18 6:34 ` [RFC PATCH 0/5] slub: Delay freezing of CPU partial slabs Hyeonggon Yoo
2023-10-18 7:44 ` Chengming Zhou
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231017154439.3036608-4-chengming.zhou@linux.dev \
--to=chengming.zhou@linux.dev \
--cc=42.hyeyoo@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
--cc=roman.gushchin@linux.dev \
--cc=vbabka@suse.cz \
--cc=zhouchengming@bytedance.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.