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From: Tim Chen <tim.c.chen@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	"Gautham R . Shenoy" <gautham.shenoy@amd.com>,
	Vincent Guittot <vincent.guittot@linaro.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	Madadi Vineeth Reddy <vineethr@linux.ibm.com>,
	Hillf Danton <hdanton@sina.com>,
	Shrikanth Hegde <sshegde@linux.ibm.com>,
	Jianyong Wu <jianyong.wu@outlook.com>,
	Yangyu Chen <cyy@cyyself.name>,
	Tingyin Duan <tingyin.duan@gmail.com>,
	Vern Hao <vernhao@tencent.com>, Vern Hao <haoxing990@gmail.com>,
	Len Brown <len.brown@intel.com>, Aubrey Li <aubrey.li@intel.com>,
	Zhao Liu <zhao1.liu@intel.com>, Chen Yu <yu.chen.surf@gmail.com>,
	Chen Yu <yu.c.chen@intel.com>,
	Adam Li <adamli@os.amperecomputing.com>,
	Aaron Lu <ziqianlu@bytedance.com>,
	Tim Chen <tim.c.chen@intel.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 10/23] sched/cache: Check local_group only once in update_sg_lb_stats()
Date: Wed,  3 Dec 2025 15:07:29 -0800	[thread overview]
Message-ID: <2581fa14a0083bbd22b50837cd86003e59192c00.1764801860.git.tim.c.chen@linux.intel.com> (raw)
In-Reply-To: <cover.1764801860.git.tim.c.chen@linux.intel.com>

There is no need to check the local group twice for both group_asym_packing
and group_smt_balance. Adjust the code to facilitate future checks for group
types (cache-aware load balancing) as well.

No functional changes are expected.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---

Notes:
    v1->v2:
       New code cleanup patch. (Peter Zijlstra)

 kernel/sched/fair.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4d7803f69a74..6e4c1ae1bdda 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10984,14 +10984,16 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
 	sgs->group_weight = group->group_weight;
 
-	/* Check if dst CPU is idle and preferred to this group */
-	if (!local_group && env->idle && sgs->sum_h_nr_running &&
-	    sched_group_asym(env, sgs, group))
-		sgs->group_asym_packing = 1;
-
-	/* Check for loaded SMT group to be balanced to dst CPU */
-	if (!local_group && smt_balance(env, sgs, group))
-		sgs->group_smt_balance = 1;
+	if (!local_group) {
+		/* Check if dst CPU is idle and preferred to this group */
+		if (env->idle && sgs->sum_h_nr_running &&
+		    sched_group_asym(env, sgs, group))
+			sgs->group_asym_packing = 1;
+
+		/* Check for loaded SMT group to be balanced to dst CPU */
+		if (smt_balance(env, sgs, group))
+			sgs->group_smt_balance = 1;
+	}
 
 	sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);
 
-- 
2.32.0


  parent reply	other threads:[~2025-12-03 23:01 UTC|newest]

Thread overview: 120+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-03 23:07 [PATCH v2 00/23] Cache aware scheduling Tim Chen
2025-12-03 23:07 ` [PATCH v2 01/23] sched/cache: Introduce infrastructure for cache-aware load balancing Tim Chen
2025-12-09 11:12   ` Peter Zijlstra
2025-12-09 21:39     ` Tim Chen
2025-12-10  9:37   ` Peter Zijlstra
2025-12-10 13:57     ` Chen, Yu C
2025-12-10 15:11       ` Peter Zijlstra
2025-12-11  9:03   ` Vern Hao
2025-12-16  6:12     ` Chen, Yu C
2025-12-17  1:17       ` Vern Hao
2026-01-15 21:47         ` Tim Chen
     [not found]   ` <fbf52d91-0605-4608-b9cc-e8cc56115fd5@gmail.com>
2025-12-16 22:30     ` Tim Chen
2025-12-03 23:07 ` [PATCH v2 02/23] sched/cache: Record per-LLC utilization to guide cache-aware scheduling decisions Tim Chen
2025-12-09 11:21   ` Peter Zijlstra
2025-12-10 14:02     ` Chen, Yu C
2025-12-10 15:13       ` Peter Zijlstra
2025-12-10 23:58         ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 03/23] sched/cache: Introduce helper functions to enforce LLC migration policy Tim Chen
2026-01-22 18:13   ` Yangyu Chen
2026-01-22 20:43     ` Tim Chen
2025-12-03 23:07 ` [PATCH v2 04/23] sched/cache: Make LLC id continuous Tim Chen
2025-12-09 11:58   ` Peter Zijlstra
2025-12-15 20:49     ` Tim Chen
2025-12-16  5:31       ` Chen, Yu C
2025-12-16 19:53         ` Tim Chen
2025-12-17  5:25           ` Chen, Yu C
2025-12-23  5:31   ` K Prateek Nayak
2025-12-24  7:08     ` Chen, Yu C
2025-12-24  8:19       ` K Prateek Nayak
2025-12-24  9:46         ` Chen, Yu C
2025-12-26  3:17           ` K Prateek Nayak
2025-12-03 23:07 ` [PATCH v2 05/23] sched/cache: Assign preferred LLC ID to processes Tim Chen
2025-12-09 12:11   ` Peter Zijlstra
2025-12-09 22:34     ` Tim Chen
2025-12-12  3:34   ` Vern Hao
2025-12-15 19:32     ` Tim Chen
2025-12-19  4:01       ` Vern Hao
2025-12-24 10:20         ` Chen, Yu C
2026-01-07  4:49   ` Jianyong Wu
2026-01-07  8:38     ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 06/23] sched/cache: Track LLC-preferred tasks per runqueue Tim Chen
2025-12-09 12:16   ` Peter Zijlstra
2025-12-09 22:55     ` Tim Chen
2025-12-10  9:42       ` Peter Zijlstra
2025-12-16  0:20         ` Chen, Yu C
2025-12-17 10:04   ` Vern Hao
2025-12-17 12:37     ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 07/23] sched/cache: Introduce per runqueue task LLC preference counter Tim Chen
2025-12-09 13:06   ` Peter Zijlstra
2025-12-09 23:17     ` Tim Chen
2025-12-10 12:43   ` Peter Zijlstra
2025-12-10 18:36     ` Tim Chen
2025-12-10 12:51   ` Peter Zijlstra
2025-12-10 18:49     ` Tim Chen
2025-12-11 10:31       ` Peter Zijlstra
2025-12-15 19:21         ` Tim Chen
2025-12-16 22:45         ` Tim Chen
2025-12-03 23:07 ` [PATCH v2 08/23] sched/cache: Calculate the per runqueue task LLC preference Tim Chen
2025-12-03 23:07 ` [PATCH v2 09/23] sched/cache: Count tasks prefering destination LLC in a sched group Tim Chen
2025-12-10 12:52   ` Peter Zijlstra
2025-12-10 14:05     ` Chen, Yu C
2025-12-10 15:16       ` Peter Zijlstra
2025-12-10 19:00         ` Tim Chen
2025-12-10 23:50         ` Chen, Yu C
2025-12-03 23:07 ` Tim Chen [this message]
2025-12-03 23:07 ` [PATCH v2 11/23] sched/cache: Prioritize tasks preferring destination LLC during balancing Tim Chen
2025-12-03 23:07 ` [PATCH v2 12/23] sched/cache: Add migrate_llc_task migration type for cache-aware balancing Tim Chen
2025-12-10 13:32   ` Peter Zijlstra
2025-12-16  0:52     ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 13/23] sched/cache: Handle moving single tasks to/from their preferred LLC Tim Chen
2025-12-03 23:07 ` [PATCH v2 14/23] sched/cache: Consider LLC preference when selecting tasks for load balancing Tim Chen
2025-12-10 15:58   ` Peter Zijlstra
2025-12-03 23:07 ` [PATCH v2 15/23] sched/cache: Respect LLC preference in task migration and detach Tim Chen
2025-12-10 16:30   ` Peter Zijlstra
2025-12-16  7:30     ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 16/23] sched/cache: Introduce sched_cache_present to enable cache aware scheduling for multi LLCs NUMA node Tim Chen
2025-12-10 16:32   ` Peter Zijlstra
2025-12-10 16:52     ` Peter Zijlstra
2025-12-16  7:36       ` Chen, Yu C
2025-12-16  7:31     ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 17/23] sched/cache: Record the number of active threads per process for cache-aware scheduling Tim Chen
2025-12-10 16:51   ` Peter Zijlstra
2025-12-16  7:40     ` Chen, Yu C
2025-12-17  9:40   ` Aaron Lu
2025-12-17 12:51     ` Chen, Yu C
2025-12-19  3:32       ` Aaron Lu
2025-12-03 23:07 ` [PATCH v2 18/23] sched/cache: Disable cache aware scheduling for processes with high thread counts Tim Chen
2025-12-03 23:07 ` [PATCH v2 19/23] sched/cache: Avoid cache-aware scheduling for memory-heavy processes Tim Chen
2025-12-18  3:59   ` Vern Hao
2025-12-18  8:32     ` Chen, Yu C
2025-12-18  9:42       ` Vern Hao
2025-12-19  3:14         ` K Prateek Nayak
2025-12-19 12:55           ` Chen, Yu C
2025-12-22  2:49             ` Vern Hao
2025-12-22  2:19           ` Vern Hao
2025-12-03 23:07 ` [PATCH v2 20/23] sched/cache: Add user control to adjust the parameters of cache-aware scheduling Tim Chen
2025-12-10 17:02   ` Peter Zijlstra
2025-12-16  7:42     ` Chen, Yu C
2025-12-19  4:14   ` Vern Hao
2025-12-19 13:21     ` Chen, Yu C
2025-12-19 13:39     ` Chen, Yu C
2025-12-23 12:12   ` Yangyu Chen
2025-12-23 16:44     ` Yangyu Chen
2025-12-24  3:28       ` Yangyu Chen
2025-12-24  7:51         ` Chen, Yu C
2025-12-24 12:15           ` Yangyu Chen
2026-01-15 10:03   ` Jianyong Wu
2026-01-15 12:13     ` Chen, Yu C
2026-01-21 15:21   ` Yangyu Chen
2026-01-21 15:38     ` Chen, Yu C
2025-12-03 23:07 ` [PATCH v2 21/23] -- DO NOT APPLY!!! -- sched/cache/stats: Add schedstat for cache aware load balancing Tim Chen
2025-12-19  5:03   ` Yangyu Chen
2025-12-19 14:41     ` Chen, Yu C
2025-12-19 14:48       ` Yangyu Chen
2025-12-03 23:07 ` [PATCH v2 22/23] -- DO NOT APPLY!!! -- sched/cache/debug: Add ftrace to track the load balance statistics Tim Chen
2025-12-03 23:07 ` [PATCH v2 23/23] -- DO NOT APPLY!!! -- sched/cache/debug: Display the per LLC occupancy for each process via proc fs Tim Chen
2025-12-17  9:59   ` Aaron Lu
2025-12-17 13:01     ` Chen, Yu C
2025-12-19  3:19 ` [PATCH v2 00/23] Cache aware scheduling Aaron Lu
2025-12-19 13:04   ` Chen, Yu C

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