From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A922837B40C; Mon, 11 May 2026 12:07:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778501244; cv=none; b=pVewIgGPyjalleN6cdMluS9lLIPi0pTWUzINb0Cb6wAVK9sZCHc6nl7S/dUnDGSaSZIhF6bfHQnaxaSz9QAI9CGHXXCou+i4/Iz1rgsuoeZyGpM/2U2oxBMVDvA57F78ieprqv3trxut5G1OErzoS/36Dy9inLGXVRqoa/i78ds= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778501244; c=relaxed/simple; bh=7WZiidKf/QSpiQu+Wq97gNh/r7ibrr9HmrfjaGfAEtA=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=rg+LeFpjia9T90lw98AG9t3IwpwFR8Xbaw7TeAx+L/gBnDSa/8mx5MlUzuylXxi9YXU4/jA582NQV6ayf/yuz9Pxd5VeWBl+QGZdyPFlUHSmoIjdAQUczTDFAsQTSjCHBFaQ7wWAyduVoLHPb5duDBD7EgvFlYIFh8+MnJg7XO8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=VF8ceFE+; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VF8ceFE+" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=H9fAEjauTnGfYqGrALj1lwI49DvVQ9DpcV3mAqAYu5I=; b=VF8ceFE+Ap4xxRZHvdWwkKjPNs tL8VLChZWU6jILDjoCrQub9kOiELAvymLlvQbbSY2npy/dEJJYaCDGE/Vo44oWEM9rxR4/Sr6M/Ck 5FmkqdAB08UT7t2gAPFixNMLwBMrtcf4p3kToLIFDS/WusPKog5/cU3RfafkiZu0FRpAbq275ZXZr EUZA2xw5KoJF18WoO3waRnCiTEniqlTBb9DsVvz/Fn9MIGa1IaRiu9laxGw/Uhp0GBy6o/V6UR9R0 /SNWRaM3sid2FXcSD50xCTiD2Rnkn6xql8bG70Xfs1faKx9NlCsxkE/zWvFUrPkxRszqw14bUm43l Hnbs6aWQ==; Received: from 2001-1c00-8d85-4b00-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:4b00:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMPPa-000000088mQ-0tbT; Mon, 11 May 2026 12:07:02 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id 20E62303038; Mon, 11 May 2026 14:07:00 +0200 (CEST) Message-ID: <20260511120627.592793383@infradead.org> User-Agent: quilt/0.68 Date: Mon, 11 May 2026 13:31:09 +0200 From: Peter Zijlstra To: mingo@kernel.org Cc: longman@redhat.com, chenridong@huaweicloud.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, jstultz@google.com, kprateek.nayak@amd.com, qyousef@layalina.io Subject: [PATCH v2 05/10] sched/fair: Add cgroup_mode: UP References: <20260511113104.563854162@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Instead of calculating the proportional fraction of tg->shares for each CPU, just give each CPU the full measure, ignoring these pesky SMP problems. Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/debug.c | 3 ++- kernel/sched/fair.c | 21 ++++++++++++++++++++- 2 files changed, 22 insertions(+), 2 deletions(-) --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -589,9 +589,10 @@ static void debugfs_fair_server_init(voi } #ifdef CONFIG_FAIR_GROUP_SCHED -int cgroup_mode = 0; +int cgroup_mode = 1; static const char *cgroup_mode_str[] = { + "up", "smp", }; --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4150,7 +4150,7 @@ static inline int throttled_hierarchy(st * * hence icky! */ -static long calc_group_shares(struct cfs_rq *cfs_rq) +static long calc_smp_shares(struct cfs_rq *cfs_rq) { long tg_weight, tg_shares, load, shares; struct task_group *tg = cfs_rq->tg; @@ -4185,6 +4185,25 @@ static long calc_group_shares(struct cfs } /* + * Ignore this pesky SMP stuff, use (4). + */ +static long calc_up_shares(struct cfs_rq *cfs_rq) +{ + struct task_group *tg = cfs_rq->tg; + return READ_ONCE(tg->shares); +} + +static long calc_group_shares(struct cfs_rq *cfs_rq) +{ + int mode = READ_ONCE(cgroup_mode); + + if (mode == 0) + return calc_up_shares(cfs_rq); + + return calc_smp_shares(cfs_rq); +} + +/* * Recomputes the group entity based on the current state of its group * runqueue. */