From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B00E3C624D4 for ; Tue, 1 Sep 2026 13:26:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 767CF6B00C8; Tue, 1 Sep 2026 09:25:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 73F296B00CE; Tue, 1 Sep 2026 09:25:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 62E236B00D0; Tue, 1 Sep 2026 09:25:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 3701F6B00C8 for ; Tue, 1 Sep 2026 09:25:33 -0400 (EDT) Received: from smtpin05.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id CD80240411 for ; Tue, 1 Sep 2026 13:25:32 +0000 (UTC) X-FDA: 85165265304.05.4A60706 Received: from mailgw1.hygon.cn (unknown [101.204.27.37]) by imf11.hostedemail.com (Postfix) with ESMTP id 94AD74000E for ; Tue, 1 Sep 2026 13:25:28 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=hygon.cn; spf=pass (imf11.hostedemail.com: domain of wujianyong@hygon.cn designates 101.204.27.37 as permitted sender) smtp.mailfrom=wujianyong@hygon.cn ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788269130; b=csaHUQNeFU21Qoi+1jQn98grFQnlnzAbyMi7AoC9yYPpcVnsoeJ1pvUCSfm3qr3fMrDWqg pM7G6ri0ZcskB7E23cT2UsswUu9hlCaowN8+bscZdlmT2eF6IR7AiggcZ/ZEk9TJjhqCIR 46IxOzvcP/q0hH/JHEMC+AITo5sKHbQ= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788269130; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PFGcAm3yDHmzGLpdn1wLQuFL5xxF0Xbr8fuHk1+xZ7U=; b=zI36NwhpTll9zzqh8sDBoYkdTDiU1YkKDkPrRBdbvSCUVxoeP5wWB5uzuZLJ/phKw1sooX 3WR8ru47KU4ACFByUeYJfK9sg1gmEdc24lxxAYdFxSrrUPrk+HwAMi9bX+c1X996ATok6C k78hetCwE22dRVEoMPxsomZaujoW7QI= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=hygon.cn; spf=pass (imf11.hostedemail.com: domain of wujianyong@hygon.cn designates 101.204.27.37 as permitted sender) smtp.mailfrom=wujianyong@hygon.cn Received: from maildlp1.hygon.cn (unknown [127.0.0.1]) by mailgw1.hygon.cn (Postfix) with ESMTP id 4hZ66q65M4z1PpLT; Tue, 1 Sep 2026 21:25:23 +0800 (CST) Received: from maildlp1.hygon.cn (unknown [172.23.18.60]) by mailgw1.hygon.cn (Postfix) with ESMTP id 4hZ66p2cBZz1PGCm; Tue, 1 Sep 2026 21:25:22 +0800 (CST) Received: from cncheex06.Hygon.cn (unknown [172.23.18.116]) by maildlp1.hygon.cn (Postfix) with ESMTPS id CFD2FB357; Tue, 1 Sep 2026 21:25:17 +0800 (CST) Received: from cncheex04.Hygon.cn (172.23.18.114) by cncheex06.Hygon.cn (172.23.18.116) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.36; Tue, 1 Sep 2026 21:25:23 +0800 Received: from cncheex04.Hygon.cn ([fe80::1b6f:6c58:58a4:430d]) by cncheex04.Hygon.cn ([fe80::1b6f:6c58:58a4:430d%10]) with mapi id 15.02.1544.036; Tue, 1 Sep 2026 21:25:23 +0800 From: Jianyong Wu To: Peter Zijlstra 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" , Yuan Zhong , Huangsj , Fengyu Wang , Zhiwei Ying , "justin.he@arm.com" Subject: RE: [RFC PATCH v2 14/23] sched/cache: Drop prefer_sibling restriction for llc_balance Thread-Topic: [RFC PATCH v2 14/23] sched/cache: Drop prefer_sibling restriction for llc_balance Thread-Index: AQHdNiBKk4QhTa7ViUqzXSOXSWPySra5Bx6AgACzrPA= Date: Tue, 1 Sep 2026 13:25:22 +0000 Message-ID: References: <20260827122816.756234-1-wujianyong@hygon.cn> <20260827122816.756234-15-wujianyong@hygon.cn> <20260901102917.GH776954@noisy.programming.kicks-ass.net> In-Reply-To: <20260901102917.GH776954@noisy.programming.kicks-ass.net> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.19.20.45] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 94AD74000E X-Stat-Signature: tiwmm9h8497wjkznsdjspwqdo775zdyp X-HE-Tag: 1788269128-57954 X-HE-Meta: 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 gEDc9c0k 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Peter, > -----Original Message----- > From: Peter Zijlstra > Sent: Tuesday, September 1, 2026 6:29 PM > 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; Yuan Zhong ; Huangsj > ; Fengyu Wang ; Zhiwei Ying > ; justin.he@arm.com > Subject: Re: [RFC PATCH v2 14/23] sched/cache: Drop prefer_sibling > restriction for llc_balance >=20 > 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 =3D=3D group_has_spare && > > - (busiest->group_type =3D=3D group_llc_balance || > > - sibling_imbalance(env, &sds, busiest, local) > 1)) > > + if (local->group_type =3D=3D group_has_spare && > > + ((busiest->group_type =3D=3D group_llc_balance) || > (sds.prefer_sibling && > > + sibling_imbalance(env, &sds, busiest, local) > 1))) > > goto force_balance; >=20 > Not sure about blanked disable. Maybe only disable when cache aware > scheduling is present and enabled? The prefer_sibling bypass is already limited to cache aware scheduling. group_llc_balance can only be selected when llc_balance() returns true, and llc_balance() immediately return false when sched aware scheduling is not active. When CONFIG_SCHED_CACHE is disabled, the corresponding stub also cannot produce group_llc_balance. Therefore, the changed branch cannot bypass prefer_sibling when cache aware scheduling is absent or disabled. Thanks Jianyong