From nobody Tue Jun 30 09:23:59 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2846EC433EF for ; Fri, 21 Jan 2022 05:03:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229598AbiAUFDD (ORCPT ); Fri, 21 Jan 2022 00:03:03 -0500 Received: from alexa-out-sd-02.qualcomm.com ([199.106.114.39]:1667 "EHLO alexa-out-sd-02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229480AbiAUFDB (ORCPT ); Fri, 21 Jan 2022 00:03:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1642741381; x=1674277381; h=from:to:cc:subject:date:message-id:mime-version; bh=qsVvbTD+kFXnw/RCOk7A0nqK86MwmdSQ061zu0NFLOY=; b=JWljXZNp5+hZiMEzDSxguJyOkOc5szadrLqiDwd7SeqiBDGeU+NP6krN 59VYhfRnesdDvQKO0QunLzJlJ94R4sG3OijgitPNbj/4s0VEBtSEf/1ZU EgOrrycAsAIAarwGkpTc5UPwch2w7xPrfK8JKQzzYyOjnzI7YZv4TgWc1 Y=; Received: from unknown (HELO ironmsg05-sd.qualcomm.com) ([10.53.140.145]) by alexa-out-sd-02.qualcomm.com with ESMTP; 20 Jan 2022 21:03:01 -0800 X-QCInternal: smtphost Received: from unknown (HELO nasanex01a.na.qualcomm.com) ([10.52.223.231]) by ironmsg05-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2022 21:03:01 -0800 Received: from hu-ctheegal-hyd.qualcomm.com (10.80.80.8) by nasanex01a.na.qualcomm.com (10.52.223.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.922.19; Thu, 20 Jan 2022 21:02:56 -0800 From: Chitti Babu Theegala To: , , , , , , CC: , , , , , Chitti Babu Theegala Subject: [PATCH v2] sched/fair: Prefer small idle cores for forkees Date: Fri, 21 Jan 2022 10:32:33 +0530 Message-ID: <20220121050233.8708-1-quic_ctheegal@quicinc.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01a.na.qualcomm.com (10.52.223.231) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Newly forked threads don't have any useful utilization data yet and it's not possible to forecast their impact on energy consumption. These forkees (though very small, most times) end up waking big cores from deep sleep for that very small durations. Bias all forkees to small cores to prevent waking big cores from deep sleep to save power. Signed-off-by: Chitti Babu Theegala --- Changes in v2: 1. Enclosed the EAS check for this small core preferring logic --- kernel/sched/fair.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c6046446c50b3..72f9ea7c98c05 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5872,7 +5872,7 @@ static int wake_affine(struct sched_domain *sd, struc= t task_struct *p, } =20 static struct sched_group * -find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this= _cpu); +find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this= _cpu, int sd_flag); =20 /* * find_idlest_group_cpu - find the idlest CPU among the CPUs in the group. @@ -5959,7 +5959,7 @@ static inline int find_idlest_cpu(struct sched_domain= *sd, struct task_struct *p continue; } =20 - group =3D find_idlest_group(sd, p, cpu); + group =3D find_idlest_group(sd, p, cpu, sd_flag); if (!group) { sd =3D sd->child; continue; @@ -8885,7 +8885,8 @@ static inline void update_sg_wakeup_stats(struct sche= d_domain *sd, static bool update_pick_idlest(struct sched_group *idlest, struct sg_lb_stats *idlest_sgs, struct sched_group *group, - struct sg_lb_stats *sgs) + struct sg_lb_stats *sgs, + int sd_flag) { if (sgs->group_type < idlest_sgs->group_type) return true; @@ -8922,6 +8923,13 @@ static bool update_pick_idlest(struct sched_group *i= dlest, if (idlest_sgs->idle_cpus > sgs->idle_cpus) return false; =20 + if (sched_energy_enabled()) { + /* Select smaller cpu group for newly woken up forkees */ + if ((sd_flag & SD_BALANCE_FORK) && (idlest_sgs->idle_cpus && + !capacity_greater(idlest->sgc->max_capacity, group->sgc->max_cap= acity))) + return false; + } + /* Select group with lowest group_util */ if (idlest_sgs->idle_cpus =3D=3D sgs->idle_cpus && idlest_sgs->group_util <=3D sgs->group_util) @@ -8940,7 +8948,7 @@ static bool update_pick_idlest(struct sched_group *id= lest, * Assumes p is allowed on at least one CPU in sd. */ static struct sched_group * -find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this= _cpu) +find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this= _cpu, int sd_flag) { struct sched_group *idlest =3D NULL, *local =3D NULL, *group =3D sd->grou= ps; struct sg_lb_stats local_sgs, tmp_sgs; @@ -8978,7 +8986,7 @@ find_idlest_group(struct sched_domain *sd, struct tas= k_struct *p, int this_cpu) =20 update_sg_wakeup_stats(sd, group, sgs, p); =20 - if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs))= { + if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs, = sd_flag)) { idlest =3D group; idlest_sgs =3D *sgs; } --=20 2.17.1