From nobody Wed Oct 8 18:13:31 2025 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 86CF21F4CB2 for ; Wed, 25 Jun 2025 19:12:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750878735; cv=none; b=rgQzsKhB23kitngGD5VyoLvqKyZx7w7V1qMvGABDbFhWxZbyps3iacMSeowKhOJQE9YmVgDKx1x1lXrkz7qGLhqd9k+0Ld3cg4looetGXOw2JvQc1olLE23fpqdVyIq0ktqmZte782Gb27La39KYhS3z7GzIkkbDAPwEV/Vdb9M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750878735; c=relaxed/simple; bh=Btfe1JJoT1bBJQ1LlBy13zZSXC2J40co3/VJFf0Ji5U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Nvu+6wcbHxVV/DcfUqin8ONHKUSTYn1VYRWwPGYGQ70ZJxRgsqP4kZTeyd2oL4Ppa2nyoJXskjt5XMq8KshKYpwF9fPEAvNvWC6YZ+Hgt09WucIWbGd5v2cr/7DMb6x58iJPZ8sxybVniWOMjvmyLOdcHhEemE0SP2oL0QWqATU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=dv3e16K4; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="dv3e16K4" Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 55PEu5h4010225; Wed, 25 Jun 2025 19:11:57 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=HqW8nqT9xu/zbT7zA lKagL9RxvS7Ysx5eO2iZlQyEhg=; b=dv3e16K4gyPcIGcVAEg0jy0QQ22eSMt7M FCvOebd8SVQ8A+3ryh2ZOsDl3hyFsMISeGR68mtLgE9cu8NXYOq+46uq0iOqNcCX XkByN5tBFGj1jKuP+jFjZGTN0ZbKBzIXTEzZJ1E1EWbSgQ9nRQeXP+CLB1Fswm5h ZoyDSNp4ScPJK1jS3pKMqz117/ZafaIvEM7i5AuxjSzq6IUbkRYFuUfKp0fzesKf 05G/OnkRaXHRT+usnm/h7umytuaBe9L1TkT2b7Ni/Pjo99er0zpF2bAdK9ZgZVej eeNNPUXwaZZI+LgktbAVAD8n8nlwdt8coCN7JDVVO8ZuDgGGeZ/MQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 47dmf394jy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 25 Jun 2025 19:11:57 +0000 (GMT) Received: from m0360072.ppops.net (m0360072.ppops.net [127.0.0.1]) by pps.reinject (8.18.0.8/8.18.0.8) with ESMTP id 55PJBuZu023746; Wed, 25 Jun 2025 19:11:56 GMT Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 47dmf394js-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 25 Jun 2025 19:11:56 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 55PHioES002471; Wed, 25 Jun 2025 19:11:56 GMT Received: from smtprelay04.fra02v.mail.ibm.com ([9.218.2.228]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 47e8jmasdn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 25 Jun 2025 19:11:56 +0000 Received: from smtpav03.fra02v.mail.ibm.com (smtpav03.fra02v.mail.ibm.com [10.20.54.102]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 55PJBqd234341558 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 25 Jun 2025 19:11:52 GMT Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 480882004B; Wed, 25 Jun 2025 19:11:52 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ABFBE20040; Wed, 25 Jun 2025 19:11:48 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.124.209.143]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 25 Jun 2025 19:11:48 +0000 (GMT) From: Shrikanth Hegde To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, yury.norov@gmail.com, maddy@linux.ibm.com Cc: sshegde@linux.ibm.com, vschneid@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, kprateek.nayak@amd.com, huschle@linux.ibm.com, srikar@linux.ibm.com, linux-kernel@vger.kernel.org, christophe.leroy@csgroup.eu, linuxppc-dev@lists.ozlabs.org, gregkh@linuxfoundation.org Subject: [RFC v2 6/9] sched/core: Push current task out if CPU is marked as avoid Date: Thu, 26 Jun 2025 00:41:05 +0530 Message-ID: <20250625191108.1646208-7-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250625191108.1646208-1-sshegde@linux.ibm.com> References: <20250625191108.1646208-1-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=M5FNKzws c=1 sm=1 tr=0 ts=685c49fd cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=6IFa9wvqVegA:10 a=VnNF1IyMAAAA:8 a=Dot9ObxFTPmaUP2n-pkA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjI1MDE0MSBTYWx0ZWRfX+CuQ7G4MP4RS 0BCK6pMAExM4hCUec36PEznclWOD/wJGxt77Alg7NG66bfJbExACF9w6m0ODCOlMVUmSrHWCXT2 CsgDQtKhYufgFvb54qhatEs1gWjTIWq6hdV9EtTqKW/53LnXSXczfmYhFFYYgag9RyPLlewx2Cc UVX1T1NkUvJvdwqZ1Xn0tjZqwBMUng1qN+dvEQTTikPakt/wz5qAVOFqvS/9oMVEvMcG1ysbagw cZl0uzUCXD6Ed2WhGu+u60V6dypIgbVt8ZMC/DkBJVh6ycqeQJmj0KW6Om7PNj83bFoYGUUzV8Z 8T9nokAUpjccyNanJYQiqROLf6qGiZFeYj8y2g1+ZZpwfmG+o+2N0X9bhff9RVGt7S9w2cprKRF mxijQIJfVYlOBc7rEDN08UeF/cHrwU4SncP0Q+MYsyJ34fpzjFzGtAzeZ0vAud/EUbUVXiaZ X-Proofpoint-GUID: V_KS9G9PtvUsA8fgxKxwlLHmIXl9DBl_ X-Proofpoint-ORIG-GUID: zNTvoP9J2-vGjp_xxArM_75tWYqFc7R0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.7,FMLib:17.12.80.40 definitions=2025-06-25_06,2025-06-25_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 impostorscore=0 suspectscore=0 priorityscore=1501 phishscore=0 spamscore=0 clxscore=1011 adultscore=0 mlxscore=0 mlxlogscore=999 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2506250141 Content-Type: text/plain; charset="utf-8" Actively push out any task running on a CPU marked as avoid.=20 If a task is sleeping it is pushed out if it wakes up on that CPU.=20 Since the task is running, need to use the stopper class to push the=20 task out. Use __balance_push_cpu_stop to achieve that.=20 This currently works only CFS and RT.=20 Signed-off-by: Shrikanth Hegde --- kernel/sched/core.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ kernel/sched/sched.h | 1 + 2 files changed, 45 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 13e44d7a0b90..aea4232e3ec4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5577,6 +5577,10 @@ void sched_tick(void) =20 sched_clock_tick(); =20 + /* push the current task out if cpu is marked as avoid */ + if (cpu_avoid(cpu)) + push_current_task(rq); + rq_lock(rq, &rf); donor =3D rq->donor; =20 @@ -8028,6 +8032,43 @@ static void balance_hotplug_wait(void) TASK_UNINTERRUPTIBLE); } =20 +static DEFINE_PER_CPU(struct cpu_stop_work, push_task_work); + +/* A CPU is marked as Avoid when there is contention for underlying + * physical CPU and using this CPU will lead to hypervisor preemptions. + * It is better not to use this CPU. + * + * In case any task is scheduled on such CPU, move it out. In + * select_fallback_rq a non_avoid CPU will be chosen and henceforth + * task shouldn't come back to this CPU + */ +void push_current_task(struct rq *rq) +{ + struct task_struct *push_task =3D rq->curr; + unsigned long flags; + + /* idle task can't be pused out */ + if (rq->curr =3D=3D rq->idle || !cpu_avoid(rq->cpu)) + return; + + /* Do for only SCHED_NORMAL AND RT for now */ + if (push_task->sched_class !=3D &fair_sched_class && + push_task->sched_class !=3D &rt_sched_class) + return; + + if (kthread_is_per_cpu(push_task) || + is_migration_disabled(push_task)) + return; + + local_irq_save(flags); + get_task_struct(push_task); + preempt_disable(); + + stop_one_cpu_nowait(rq->cpu, __balance_push_cpu_stop, push_task, + this_cpu_ptr(&push_task_work)); + preempt_enable(); + local_irq_restore(flags); +} #else /* !CONFIG_HOTPLUG_CPU: */ =20 static inline void balance_push(struct rq *rq) @@ -8042,6 +8083,9 @@ static inline void balance_hotplug_wait(void) { } =20 +void push_current_task(struct rq *rq) +{ +} #endif /* !CONFIG_HOTPLUG_CPU */ =20 void set_rq_online(struct rq *rq) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 105190b18020..b9614873762e 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1709,6 +1709,7 @@ struct rq_flags { }; =20 extern struct balance_callback balance_push_callback; +void push_current_task(struct rq *rq); =20 #ifdef CONFIG_SCHED_CLASS_EXT extern const struct sched_class ext_sched_class; --=20 2.43.0