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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 3B006C433ED for ; Wed, 14 Apr 2021 14:49:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1BA50611B0 for ; Wed, 14 Apr 2021 14:49:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344527AbhDNOuA (ORCPT ); Wed, 14 Apr 2021 10:50:00 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:3335 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231825AbhDNOt7 (ORCPT ); Wed, 14 Apr 2021 10:49:59 -0400 Received: from DGGEML404-HUB.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4FL4z76Yv3z14G5J; Wed, 14 Apr 2021 22:45:55 +0800 (CST) Received: from dggpeml500013.china.huawei.com (7.185.36.41) by DGGEML404-HUB.china.huawei.com (10.3.17.39) with Microsoft SMTP Server (TLS) id 14.3.498.0; Wed, 14 Apr 2021 22:49:34 +0800 Received: from [10.174.187.161] (10.174.187.161) by dggpeml500013.china.huawei.com (7.185.36.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2106.2; Wed, 14 Apr 2021 22:49:33 +0800 Subject: Re: [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs_vmx for Ice Lake Servers To: Like Xu References: <20210329054137.120994-2-like.xu@linux.intel.com> <606BD46F.7050903@huawei.com> <18597e2b-3719-8d0d-9043-e9dbe39496a2@intel.com> <60701165.3060000@huawei.com> <1ba15937-ee3d-157a-e891-981fed8b414d@linux.intel.com> CC: , "Fangyi (Eric)" , Xiexiangyou , , , , , , "Xu, Like" From: Liuxiangdong Message-ID: <607700F2.9080409@huawei.com> Date: Wed, 14 Apr 2021 22:49:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <1ba15937-ee3d-157a-e891-981fed8b414d@linux.intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.187.161] X-ClientProxiedBy: dggeme716-chm.china.huawei.com (10.1.199.112) To dggpeml500013.china.huawei.com (7.185.36.41) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Like, On 2021/4/9 16:46, Like Xu wrote: > Hi Liuxiangdong, > > On 2021/4/9 16:33, Liuxiangdong (Aven, Cloud Infrastructure Service > Product Dept.) wrote: >> Do you have any comments or ideas about it ? >> >> https://lore.kernel.org/kvm/606E5EF6.2060402@huawei.com/ > > My expectation is that there may be many fewer PEBS samples > on Skylake without any soft lockup. > > You may need to confirm the statement > > "All that matters is that the EPT pages don't get > unmapped ever while PEBS is active" > > is true in the kernel level. > > Try "-overcommit mem-lock=on" for your qemu. > Sorry, in fact, I don't quite understand "My expectation is that there may be many fewer PEBS samples on Skylake without any soft lockup. " And, I have used "-overcommit mem-lock=on" when soft lockup happens. Now, I have tried to configure 1G-hugepages for 2G-mem vm. Each of guest numa nodes has 1G mem. When I use pebs(perf record -e cycles:pp) in guest, there are successful pebs samples just for a while and then I cannot get pebs samples. Host doesn't soft lockup in this process. Are there something wrong on skylake for we can only get a few samples? IRQ? Or using hugepage is not effecitve? Thanks! >> >> >> On 2021/4/6 13:14, Xu, Like wrote: >>> Hi Xiangdong, >>> >>> On 2021/4/6 11:24, Liuxiangdong (Aven, Cloud Infrastructure Service >>> Product Dept.) wrote: >>>> Hi，like. >>>> Some questions about this new pebs patches set： >>>> https://lore.kernel.org/kvm/20210329054137.120994-2-like.xu@linux.intel.com/ >>>> >>>> >>>> The new hardware facility supporting guest PEBS is only available >>>> on Intel Ice Lake Server platforms for now. >>> >>> Yes, we have documented this "EPT-friendly PEBS" capability in the SDM >>> 18.3.10.1 Processor Event Based Sampling (PEBS) Facility >>> >>> And again, this patch set doesn't officially support guest PEBS on >>> the Skylake. >>> >>>> >>>> >>>> AFAIK， Icelake supports adaptive PEBS and extended PEBS which >>>> Skylake doesn't. >>>> But we can still use IA32_PEBS_ENABLE MSR to indicate >>>> general-purpose counter in Skylake. >>> >>> For Skylake, only the PMC0-PMC3 are valid for PEBS and you may >>> mask the other unsupported bits in the pmu->pebs_enable_mask. >>> >>>> Is there anything else that only Icelake supports in this patches set? >>> >>> The PDIR counter on the Ice Lake is the fixed counter 0 >>> while the PDIR counter on the Sky Lake is the gp counter 1. >>> >>> You may also expose x86_pmu.pebs_vmx for Skylake in the 1st patch. >>> >>>> >>>> >>>> Besides, we have tried this patches set in Icelake. We can use >>>> pebs(eg: "perf record -e cycles:pp") >>>> when guest is kernel-5.11, but can't when kernel-4.18. Is there a >>>> minimum guest kernel version requirement? >>> >>> The Ice Lake CPU model has been added since v5.4. >>> >>> You may double check whether the stable tree(s) code has >>> INTEL_FAM6_ICELAKE in the arch/x86/include/asm/intel-family.h. >>> >>>> >>>> >>>> Thanks, >>>> Xiangdong Liu >>> >> >