linux-kernel - [tip: core/debugobjects] debugobjects: Collect newly allocated objects in a list to reduce lock contention

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Message-ID: <172900658871.1442.11609364192319845357.tip-bot2@tip-bot2>
Date: Tue, 15 Oct 2024 15:36:28 -0000
From: "tip-bot2 for Zhen Lei" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Zhen Lei <thunder.leizhen@...wei.com>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: core/debugobjects] debugobjects: Collect newly allocated
 objects in a list to reduce lock contention

The following commit has been merged into the core/debugobjects branch of tip:

Commit-ID:     813fd07858cfb410bc9574c05b7922185f65989b
Gitweb:        https://git.kernel.org/tip/813fd07858cfb410bc9574c05b7922185f65989b
Author:        Zhen Lei <thunder.leizhen@...wei.com>
AuthorDate:    Mon, 07 Oct 2024 18:49:53 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 15 Oct 2024 17:30:30 +02:00

debugobjects: Collect newly allocated objects in a list to reduce lock contention

Collect the newly allocated debug objects in a list outside the lock, so
that the lock held time and the potential lock contention is reduced.

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/all/20240911083521.2257-3-thunder.leizhen@huawei.com
Link: https://lore.kernel.org/all/20241007164913.073653668@linutronix.de


---
 lib/debugobjects.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index df48acc..798ce5a 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -161,23 +161,25 @@ static void fill_pool(void)
 		return;
 
 	while (READ_ONCE(obj_pool_free) < debug_objects_pool_min_level) {
-		struct debug_obj *new[ODEBUG_BATCH_SIZE];
+		struct debug_obj *new, *last = NULL;
+		HLIST_HEAD(head);
 		int cnt;
 
 		for (cnt = 0; cnt < ODEBUG_BATCH_SIZE; cnt++) {
-			new[cnt] = kmem_cache_zalloc(obj_cache, gfp);
-			if (!new[cnt])
+			new = kmem_cache_zalloc(obj_cache, gfp);
+			if (!new)
 				break;
+			hlist_add_head(&new->node, &head);
+			if (!last)
+				last = new;
 		}
 		if (!cnt)
 			return;
 
 		raw_spin_lock_irqsave(&pool_lock, flags);
-		while (cnt) {
-			hlist_add_head(&new[--cnt]->node, &obj_pool);
-			debug_objects_allocated++;
-			WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
-		}
+		hlist_splice_init(&head, &last->node, &obj_pool);
+		debug_objects_allocated += cnt;
+		WRITE_ONCE(obj_pool_free, obj_pool_free + cnt);
 		raw_spin_unlock_irqrestore(&pool_lock, flags);
 	}
 }