From mboxrd@z Thu Jan 1 00:00:00 1970 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 A3D46175BF for ; Fri, 15 Mar 2024 09:26:09 +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=1710494771; cv=none; b=omvqMgYxZQ03wnClotqtSyz44MZrIvQbSa+O8WNef4+uDGRu864LeRNXafcfX8PL5/kDibWoyQYUqHhJwTfIwA452ofc6Kwh3pDXU5g1Z6ofG5sVxt/Q+BoYNLo2W4INuNBGfCtpKFJYg2s6bgMuLy3jPMa/xBTngrQMPoCg9DQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710494771; c=relaxed/simple; bh=MReRIJrlX8O9MT/+6kJslqNYwHtGqTuoDN2PocAehRQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=syXChnwsEXFOs6XtQs+M7BtPXutKKH2H9jah+44b54ME16YQcJq5ttQ3GoIUd6jXFfL5Aa7C/P8YBNwIqIqP/ve3DMhbIVEdyrZtBCeynrmUqNbWNqIWyES9FOUF+zV/gPZ6ait6q/Pz1eJ74tBzk2WDgF4UvVOgxdUeJlyYDzA= 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=pzN2QS5O; 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="pzN2QS5O" Received: from pps.filterd (m0353722.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 42F8tE0n008889; Fri, 15 Mar 2024 09:26:00 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=KvLLWTMK+Jze46m0R5HmxFbZSHGWN2mqFJV6H+SLzAQ=; b=pzN2QS5OGKtasOskysZFdZ3WdeB6NFfep3yakeYGEBSf4t9LM8jqPFKIT6o5BNI2oRnU /IdxkUWtAPpjUS0uZpgXlg0UzODvYtJfNT+2aoComG/hQtvQ0PrIc5A7kgaKLS2sh0yc Af2LyYxCzH6DDenYeFwplx7ASam3Ha2J6IAKAH9XuMZBqPDlR/I9nHssx7i+psL4/o+3 5+JuGwGLv4ME8Ktu6iaotXKgHRIy7YXLd3l/RUQsR5iS+j+7Wt3gms05WeoH8qVMtKvz +U9CHDbEB6AOTkCXlPWcXhEg/jteVVdzG02bLedUqKvnOv6kte786zSDqagSUvr3kYkH Jw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3wvhcj9qq9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Mar 2024 09:26:00 +0000 Received: from m0353722.ppops.net (m0353722.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 42F9PAm4015856; Fri, 15 Mar 2024 09:25:59 GMT Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3wvhcj9qq4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Mar 2024 09:25:59 +0000 Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 42F6MaZa018143; Fri, 15 Mar 2024 09:25:59 GMT Received: from smtprelay04.wdc07v.mail.ibm.com ([172.16.1.71]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 3ws23tu5hn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Mar 2024 09:25:59 +0000 Received: from smtpav05.wdc07v.mail.ibm.com (smtpav05.wdc07v.mail.ibm.com [10.39.53.232]) by smtprelay04.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 42F9PuZ111076216 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 15 Mar 2024 09:25:58 GMT Received: from smtpav05.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4E46F58068; Fri, 15 Mar 2024 09:25:56 +0000 (GMT) Received: from smtpav05.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3E7FA5805F; Fri, 15 Mar 2024 09:25:54 +0000 (GMT) Received: from [9.124.31.199] (unknown [9.124.31.199]) by smtpav05.wdc07v.mail.ibm.com (Postfix) with ESMTP; Fri, 15 Mar 2024 09:25:53 +0000 (GMT) Message-ID: Date: Fri, 15 Mar 2024 14:55:52 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/10] sched/balancing: Switch the 'DEFINE_SPINLOCK(balancing)' spinlock into an 'atomic_t sched_balance_running' flag Content-Language: en-US To: Ingo Molnar Cc: Dietmar Eggemann , Peter Zijlstra , Valentin Schneider , Vincent Guittot , LKML References: <20240308105901.1096078-1-mingo@kernel.org> <20240308105901.1096078-2-mingo@kernel.org> From: Shrikanth Hegde In-Reply-To: <20240308105901.1096078-2-mingo@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Voe-nRTJtijgLpYjzGClX1GNpleG_j10 X-Proofpoint-ORIG-GUID: TTF9Mi1eGrjybl0gwHTJwMV7sGkjQstF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-14_13,2024-03-13_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=999 clxscore=1015 impostorscore=0 adultscore=0 suspectscore=0 malwarescore=0 spamscore=0 phishscore=0 lowpriorityscore=0 mlxscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2403150076 On 3/8/24 4:28 PM, Ingo Molnar wrote: > The 'balancing' spinlock added in: > > Also document the flag a bit. > > No change in functionality intended. > > -static DEFINE_SPINLOCK(balancing); > +/* > + * This flag serializes load-balancing passes over large domains > + * (above the NODE topology level) - only one load-balancing instance > + * may run at a time, to reduce overhead on very large systems with > + * lots of CPUs and large NUMA distances. > + * > + * - Note that load-balancing passes triggered while another one > + * is executing are skipped and not re-tried. > + * > + * - Also note that this does not serialize rebalance_domains() nit: please change rebalance_domains to sched_balance_domains. > + * execution, as non-SD_SERIALIZE domains will still be > + * load-balanced in parallel. > + */ > +static atomic_t sched_balance_running = ATOMIC_INIT(0); > > /* > * Scale the max load_balance interval with the number of CPUs in the system. > @@ -11711,7 +11724,7 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) > > need_serialize = sd->flags & SD_SERIALIZE; > if (need_serialize) {