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 9EFAFC43603 for ; Thu, 5 Dec 2019 16:16:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A15420801 for ; Thu, 5 Dec 2019 16:16:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729962AbfLEQQi (ORCPT ); Thu, 5 Dec 2019 11:16:38 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:19612 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729430AbfLEQQf (ORCPT ); Thu, 5 Dec 2019 11:16:35 -0500 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xB5GCrk0025762; Thu, 5 Dec 2019 11:16:27 -0500 Received: from ppma05wdc.us.ibm.com (1b.90.2fa9.ip4.static.sl-reverse.com [169.47.144.27]) by mx0a-001b2d01.pphosted.com with ESMTP id 2wpur469s5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 05 Dec 2019 11:16:27 -0500 Received: from pps.filterd (ppma05wdc.us.ibm.com [127.0.0.1]) by ppma05wdc.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id xB5GFPhT019887; Thu, 5 Dec 2019 16:16:25 GMT Received: from b01cxnp22035.gho.pok.ibm.com (b01cxnp22035.gho.pok.ibm.com [9.57.198.25]) by ppma05wdc.us.ibm.com with ESMTP id 2wkg27r1ky-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 05 Dec 2019 16:16:25 +0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp22035.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xB5GGPpB17695078 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 5 Dec 2019 16:16:25 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 554BD112066; Thu, 5 Dec 2019 16:16:25 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 38977112061; Thu, 5 Dec 2019 16:16:25 +0000 (GMT) Received: from localhost (unknown [9.41.101.192]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 5 Dec 2019 16:16:25 +0000 (GMT) From: Nathan Lynch To: Kamalesh Babulal Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Michael Ellerman , Vaidyanathan Srinivasan , "Naveen N. Rao" , Tyrel Datwyler , "Gautham R. Shenoy" Subject: Re: [PATCH 0/3] pseries: Track and expose idle PURR and SPURR ticks In-Reply-To: <48823589-b105-0da3-e532-f633ade8f0d9@linux.vnet.ibm.com> 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> Date: Thu, 05 Dec 2019 10:16:19 -0600 Message-ID: <87k17au4rw.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 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 phishscore=0 spamscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 malwarescore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 bulkscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912050135 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kamalesh, 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. >> >> Does anything really want to use PURR instead of SPURR? Seems like we >> should expose only SPURR idle values if possible. >> > > lparstat is one of the consumers of PURR idle metric > (https://groups.google.com/forum/#!topic/powerpc-utils-devel/fYRo69xO9r4). > Agree, on the argument that system utilization metrics based on SPURR > accounting is accurate in comparison to PURR, which isn't proportional to > CPU frequency. PURR has been traditionally used to understand the system > utilization, whereas SPURR is used for understanding how much capacity is > left/exceeding in the system based on the current power saving mode. 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.