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 68647239083; Mon, 14 Apr 2025 07:15:33 +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=1744614937; cv=none; b=D8rfxXvYej8cry7NyH7STCzGWawqNv85ImbBtafvZcYKe1bJmHsc3UEWMOPPXSXugxj7Ec7BkgV67avtbBAPiG71hL+YbQMEk1+vwkqLOWszHXQ/HIIdFhJ1qKWgsN/NdZUDhcfBdl5u55bs/azfZDsiNHNMPb318HC2VokVrVc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744614937; c=relaxed/simple; bh=Tw2tXWs2wGcWRTPB0gJYGHNMRJ7yGZsEUJwm+877cbg=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=lu6JwR9zIstucU4bkNDfS2QkGHB4hMF+AhJBCjWM6vFTlfY3+HNU5V8jco09j0b66wtSddwXcVd9qJ+yG+tOrcnUmW5766kQXBY8e0d+iiaDIlm0l1sZW7LO3jmfcN6JUMk2I3AutRSpOFZN0SmHDVkyQNf3DC7lfGq7lVaF03M= 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=GwG03lGK; 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="GwG03lGK" Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 53E708fH025241; Mon, 14 Apr 2025 07:15:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=Tw2tXW s2wGcWRTPB0gJYGHNMRJ7yGZsEUJwm+877cbg=; b=GwG03lGKemGPtTBlyeeP7z t5PiQtP/NQoZ8ZIaxdgVmAeKI2Qo8W/+LXMLBaSrbHsHmBApl4BJIQhU4jHRF5Yq 2uFBnIEx61zaLFsnM07EDNY5Y62akaP2fVnL5ZOO+FKy8D2xY6iETh8QYih2rbta MfOQ+AxqWOGqy0YdxARMK4ahvAmEZ7KrLAEjKR92pDwEa0bl48viavBkzLzZYIe7 FJmuIn+GdhuRBa+F7QoepQURCx8FzA7wHMSEnsKguL6BV1YKAqNzycOKW4XxRGxr jlPmHF+D+avU+BKaLJkH6fOuFbOP14M8qZONd9Lj0gPoBEcl69cgsWZ/Ie1lUs4Q == Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 460bqpb8gd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 14 Apr 2025 07:15:27 +0000 (GMT) Received: from m0356516.ppops.net (m0356516.ppops.net [127.0.0.1]) by pps.reinject (8.18.0.8/8.18.0.8) with ESMTP id 53E7FQNP001293; Mon, 14 Apr 2025 07:15:26 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 460bqpb8ga-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 14 Apr 2025 07:15:26 +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 53E3vXLw017170; Mon, 14 Apr 2025 07:15:25 GMT Received: from smtprelay03.wdc07v.mail.ibm.com ([172.16.1.70]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 46040kn0d9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 14 Apr 2025 07:15:25 +0000 Received: from smtpav03.dal12v.mail.ibm.com (smtpav03.dal12v.mail.ibm.com [10.241.53.102]) by smtprelay03.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 53E7FNTW21955250 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 14 Apr 2025 07:15:23 GMT Received: from smtpav03.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 489C758061; Mon, 14 Apr 2025 07:15:25 +0000 (GMT) Received: from smtpav03.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F09DB58056; Mon, 14 Apr 2025 07:15:21 +0000 (GMT) Received: from li-c18b6acc-24ee-11b2-a85c-81492619bda1.ibm.com (unknown [9.43.55.58]) by smtpav03.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 14 Apr 2025 07:15:21 +0000 (GMT) Message-ID: <23742d13848a8cdf24da43c08ebe061211f46ecc.camel@linux.ibm.com> Subject: Re: [PATCH v1 0/2] cpuidle: teo: Refine handling of short idle intervals From: Aboorva Devarajan To: "Rafael J. Wysocki" , Linux PM Cc: LKML , Daniel Lezcano , Christian Loehle , Artem Bityutskiy , Doug Smythies Date: Mon, 14 Apr 2025 12:45:20 +0530 In-Reply-To: <4661520.LvFx2qVVIh@rjwysocki.net> References: <4661520.LvFx2qVVIh@rjwysocki.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: Qgar2r_EoA08XHseT2LeY_WhDTieWko- X-Proofpoint-GUID: CsHK94dMR4RWHs-9S7HhOpJZ1qXzrPII X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-14_01,2025-04-10_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 adultscore=0 mlxscore=0 bulkscore=0 mlxlogscore=643 spamscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504140049 On Thu, 2025-04-03 at 21:16 +0200, Rafael J. Wysocki wrote: > Hi Everyone, >=20 > This series is intended to address an issue with overly aggressive select= ion > of idle state 0 (the polling state) in teo on x86 in some cases when time= r > wakeups dominate the CPU wakeup pattern. >=20 > In those cases, timer wakeups are not taken into account when they are > within the LATENCY_THRESHOLD_NS range and the idle state selection may > be based entirely on non-timer wakeups which may be rare.=C2=A0 This caus= es > the prediction accuracy to be low and too much energy may be used as > a result. >=20 > The first patch is preparatory and it is not expected to make any > functional difference. >=20 > The second patch causes teo to take timer wakeups into account if it > is about to skip the tick_nohz_get_sleep_length() invocation, so they > get a chance to influence the idle state selection. >=20 > I have been using this series on my systems for several weeks and observe= d > a significant reduction of the polling state selection rate in multiple > workloads. >=20 > Thanks! >=20 >=20 Hi Rafael, I'm running some tests and going through the patch. I haven't noticed any deviations so far, will post the results shortly. Thanks, Aboorva