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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 1428AC43603 for ; Thu, 5 Dec 2019 17:27:29 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6841E2464D for ; Thu, 5 Dec 2019 17:27:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6841E2464D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.vnet.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47TN2N5D9BzDqbv for ; Fri, 6 Dec 2019 04:27:24 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=naveen.n.rao@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 47TMzy4c9vzDqZb for ; Fri, 6 Dec 2019 04:25:18 +1100 (AEDT) Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xB5HM5RP136723 for ; Thu, 5 Dec 2019 12:25:15 -0500 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2wq5t8s0t0-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 05 Dec 2019 12:25:14 -0500 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 5 Dec 2019 17:25:10 -0000 Received: from b06cxnps4075.portsmouth.uk.ibm.com (9.149.109.197) by e06smtp03.uk.ibm.com (192.168.101.133) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 5 Dec 2019 17:25:08 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xB5HP67N59506886 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 5 Dec 2019 17:25:06 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BB11AA4069; Thu, 5 Dec 2019 17:25:06 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 67935A404D; Thu, 5 Dec 2019 17:25:06 +0000 (GMT) Received: from localhost (unknown [9.199.48.150]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 5 Dec 2019 17:25:06 +0000 (GMT) Date: Thu, 05 Dec 2019 22:55:05 +0530 From: "Naveen N. Rao" Subject: Re: [PATCH 0/3] pseries: Track and expose idle PURR and SPURR ticks To: Kamalesh Babulal , Nathan Lynch References: <1574856072-30972-1-git-send-email-ego@linux.vnet.ibm.com> <87r21ju3ud.fsf@linux.ibm.com> <48823589-b105-0da3-e532-f633ade8f0d9@linux.vnet.ibm.com> <87k17au4rw.fsf@linux.ibm.com> In-Reply-To: <87k17au4rw.fsf@linux.ibm.com> MIME-Version: 1.0 User-Agent: astroid/v0.15-13-gb675b421 (https://github.com/astroidmail/astroid) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 x-cbid: 19120517-0012-0000-0000-00000371BA17 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19120517-0013-0000-0000-000021AD7FD0 Message-Id: <1575566328.nhfi897fmd.naveen@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-05_05:2019-12-04,2019-12-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 impostorscore=0 malwarescore=0 bulkscore=0 priorityscore=1501 adultscore=0 mlxlogscore=999 spamscore=0 clxscore=1015 suspectscore=0 phishscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912050146 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tyrel Datwyler , "Gautham R. Shenoy" , linux-kernel@vger.kernel.org, Vaidyanathan Srinivasan , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Nathan, Nathan Lynch wrote: > Hi Kamalesh, >=20 > Kamalesh Babulal writes: >> On 12/5/19 3:54 AM, Nathan Lynch wrote: >>> "Gautham R. Shenoy" writes: >>>> >>>> Tools such as lparstat which are used to compute the utilization need >>>> to know [S]PURR ticks when the cpu was busy or idle. The [S]PURR >>>> counters are already exposed through sysfs. We already account for >>>> PURR ticks when we go to idle so that we can update the VPA area. This >>>> patchset extends support to account for SPURR ticks when idle, and >>>> expose both via per-cpu sysfs files. >>>=20 >>> Does anything really want to use PURR instead of SPURR? Seems like we >>> should expose only SPURR idle values if possible. >>>=20 >> >> lparstat is one of the consumers of PURR idle metric >> (https://groups.google.com/forum/#!topic/powerpc-utils-devel/fYRo69xO9r4= ).=20 >> Agree, on the argument that system utilization metrics based on SPURR >> accounting is accurate in comparison to PURR, which isn't proportional t= o >> CPU frequency. PURR has been traditionally used to understand the syste= m >> utilization, whereas SPURR is used for understanding how much capacity i= s >> left/exceeding in the system based on the current power saving mode. >=20 > I'll phrase my question differently: does SPURR complement or supercede > PURR? You seem to be saying they serve different purposes. If PURR is > actually useful rather then vestigial then I have no objection to > exposing idle_purr. SPURR complements PURR, so we need both. SPURR/PURR ratio helps provide=20 an indication of the available headroom in terms of core resources, at=20 maximum frequency. - Naveen