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_PASS,URIBL_BLOCKED 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 6FA43C43382 for ; Fri, 28 Sep 2018 04:34:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2B4C5216FE for ; Fri, 28 Sep 2018 04:34:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B4C5216FE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728733AbeI1K4M (ORCPT ); Fri, 28 Sep 2018 06:56:12 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39878 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726271AbeI1K4L (ORCPT ); Fri, 28 Sep 2018 06:56:11 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w8S4YMOi057633 for ; Fri, 28 Sep 2018 00:34:23 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2msbfv3kst-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 28 Sep 2018 00:34:23 -0400 Received: from localhost by e06smtp02.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, 28 Sep 2018 05:33:57 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w8S4XuD964815142 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 28 Sep 2018 04:33:56 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AB0B64C04E; Fri, 28 Sep 2018 07:33:39 +0100 (BST) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1B9684C04A; Fri, 28 Sep 2018 07:33:38 +0100 (BST) Received: from [9.124.35.65] (unknown [9.124.35.65]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 28 Sep 2018 07:33:37 +0100 (BST) Subject: Re: [PATCH v3 1/1] perf: Sharing PMU counters across compatible events To: Song Liu Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, Tejun Heo , Peter Zijlstra , Jiri Olsa , Alexey Budankov , Ravi Bangoria , "Naveen N. Rao" , Madhavan Srinivasan References: <20180924222517.197296-1-songliubraving@fb.com> <20180924222517.197296-2-songliubraving@fb.com> From: Ravi Bangoria Date: Fri, 28 Sep 2018 10:03:54 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180924222517.197296-2-songliubraving@fb.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18092804-0008-0000-0000-000002780EF4 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18092804-0009-0000-0000-000021E119B6 Message-Id: <0b57307e-b75c-5df8-1ea7-27d527577489@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-09-28_01:,, 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=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809280048 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Song, On 09/25/2018 03:55 AM, Song Liu wrote: > This patch tries to enable PMU sharing. To make perf event scheduling > fast, we use special data structures. > > An array of "struct perf_event_dup" is added to the perf_event_context, > to remember all the duplicated events under this ctx. All the events > under this ctx has a "dup_id" pointing to its perf_event_dup. Compatible > events under the same ctx share the same perf_event_dup. The following > figure shows a simplified version of the data structure. > > ctx -> perf_event_dup -> master > ^ > | > perf_event /| > | > perf_event / > I've not gone through the patch in detail, but I was specifically interested in scenarios where one perf instance is counting event systemwide and thus other perf instance fails to count the same event for a specific workload because that event can be counted in one hw counter only. Ex: https://lkml.org/lkml/2018/3/12/1011 Seems this patch does not solve this issue. Please let me know if I'm missing anything. Thanks, Ravi