From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9A93C43381 for ; Fri, 22 Mar 2019 06:26:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77A51218E2 for ; Fri, 22 Mar 2019 06:26:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727571AbfCVG0J (ORCPT ); Fri, 22 Mar 2019 02:26:09 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:56172 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726096AbfCVG0I (ORCPT ); Fri, 22 Mar 2019 02:26:08 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2M6J6Hu079824 for ; Fri, 22 Mar 2019 02:26:07 -0400 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rct68rkah-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 22 Mar 2019 02:26:07 -0400 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 22 Mar 2019 06:25:53 -0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2M6Q1Nq62652420 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Mar 2019 06:26:01 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 132ECAE053; Fri, 22 Mar 2019 06:26:01 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E1C15AE045; Fri, 22 Mar 2019 06:25:59 +0000 (GMT) Received: from boston16h.aus.stglabs.ibm.com (unknown [9.3.23.78]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 22 Mar 2019 06:25:59 +0000 (GMT) From: Abhishek Goel To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org Cc: rjw@rjwysocki.net, daniel.lezcano@linaro.org, mpe@ellerman.id.au, Abhishek Goel Subject: [PATCH 0/2] Auto-promotion logic for cpuidle states Date: Fri, 22 Mar 2019 01:25:28 -0500 X-Mailer: git-send-email 2.17.1 X-TM-AS-GCONF: 00 x-cbid: 19032206-0016-0000-0000-00000265CFBC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032206-0017-0000-0000-000032C0F2E9 Message-Id: <20190322062530.7586-1-huntbag@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-22_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=528 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903220048 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, the cpuidle governors (menu/ladder) determine what idle state a idling CPU should enter into based on heuristics that depend on the idle history on that CPU. Given that no predictive heuristic is perfect, there are cases where the governor predicts a shallow idle state, hoping that the CPU will be busy soon. However, if no new workload is scheduled on that CPU in the near future, the CPU will end up in the shallow state. Motivation ---------- In case of POWER, this is problematic, when the predicted state in the aforementioned scenario is a lite stop state, as such lite states will inhibit SMT folding, thereby depriving the other threads in the core from using the core resources. To address this, such lite states need to be autopromoted. The cpuidle-core can queue timer to correspond with the residency value of the next available state. Thus leading to auto-promotion to a deeper idle state as soon as possible. Experiment ---------- Without this patch - It was seen that for a idle system, a cpu may remain in stop0_lite for few seconds and then directly goes to a deeper state such as stop2. With this patch - A cpu will not remain in stop0_lite for more than the residency of next available state, and thus it will go to a deeper state in conservative fashion. Using this, we may spent even less than 20 milliseconds if susbsequent stop states are enabled. In the worst case, we may end up spending more than a second, as was the case without this patch. The worst case will occur in the scenario when no other shallow states are enbaled, and only deep states are available for auto-promotion. Abhishek Goel (2): cpuidle : auto-promotion for cpuidle states cpuidle : Add auto-promotion flag to cpuidle flags arch/powerpc/include/asm/opal-api.h | 1 + drivers/cpuidle/Kconfig | 4 ++++ drivers/cpuidle/cpuidle-powernv.c | 13 +++++++++++-- drivers/cpuidle/cpuidle.c | 3 --- 4 files changed, 16 insertions(+), 5 deletions(-) -- 2.17.1