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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.99.2 #2 (Red Hat Linux)) id 1x1Ljy-0000000Ar4c-1mv8; Tue, 01 Sep 2026 10:29:18 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 43DED30031E; Tue, 01 Sep 2026 12:29:17 +0200 (CEST) Date: Tue, 1 Sep 2026 12:29:17 +0200 From: Peter Zijlstra To: Jianyong Wu Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Chen Yu , Tim Chen , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Shrikanth Hegde , Phil Auld , Andrew Morton , David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, jianyong.wu@outlook.com, zhongyuan@hygon.cn, huangsj@hygon.cn, wangfengyu@hygon.cn, yingzhiwei@hygon.cn, justin.he@arm.com Subject: Re: [RFC PATCH v2 14/23] sched/cache: Drop prefer_sibling restriction for llc_balance Message-ID: <20260901102917.GH776954@noisy.programming.kicks-ass.net> References: <20260827122816.756234-1-wujianyong@hygon.cn> <20260827122816.756234-15-wujianyong@hygon.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260827122816.756234-15-wujianyong@hygon.cn> X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: CDA28C0007 X-Stat-Signature: zximq91mpfd3u44eq9wb5ehkn3hbi9q5 X-HE-Tag: 1788258566-289570 X-HE-Meta: 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 MRctIp9Q eud1r/uBSloB70xNm+kl/+mqFcAUw6u8nP7S7VDo3b9rahbUz7vXxJuRHZVwPyGwi3rz54eNUu9sR/4uSsOC4lUUpBo771OSJT3QbAooN3MpC6YAyp6D0WN5gL5/Jsa63PChztEOVCPb0vZHvR7WZ7mZ+vkO7qbASPSC7+y6F7zLT6go72Ci8TnatFBTNDyET28PweQxuYyHxwAXPR3X0qEY2h8dztdyCUUm+CLY7CFKTfWH4A7AyFxE/PlpXQGVD0N+T Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 27, 2026 at 08:28:07PM +0800, Jianyong Wu wrote: > group_llc_balance performs balancing across LLC and NUMA domains. > The prefer_sibling constraint unnecessarily limits its scope, so remove > this requirement entirely from the branch condition. > > Signed-off-by: Jianyong Wu > --- > kernel/sched/fair.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 584297528a9e..5c35a43e5e38 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -13274,9 +13274,9 @@ static struct sched_group *sched_balance_find_src_group(struct lb_env *env) > * Try to move all excess tasks to a sibling domain of the busiest > * group's child domain. > */ > - if (sds.prefer_sibling && local->group_type == group_has_spare && > - (busiest->group_type == group_llc_balance || > - sibling_imbalance(env, &sds, busiest, local) > 1)) > + if (local->group_type == group_has_spare && > + ((busiest->group_type == group_llc_balance) || (sds.prefer_sibling && > + sibling_imbalance(env, &sds, busiest, local) > 1))) > goto force_balance; Not sure about blanked disable. Maybe only disable when cache aware scheduling is present and enabled?