From patchwork Tue Aug 8 06:30:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Mi, Dapeng" X-Patchwork-Id: 13346997 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF972C04A6A for ; Tue, 8 Aug 2023 20:42:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229553AbjHHUmq (ORCPT ); Tue, 8 Aug 2023 16:42:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229834AbjHHUls (ORCPT ); Tue, 8 Aug 2023 16:41:48 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8AAE78DCCF; Tue, 8 Aug 2023 10:31:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1691515897; x=1723051897; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=eqRRMLl2kIoz0ZwHwY02c6d7SX45/i2Q/jssTnU7/tA=; b=JmKkWqIA0/GVc8tGbrgwAMTXe8xpEcUH9BPs/q6KFqCy17gspPRcU9tt gHlw+wnwJLuV7Fodg4OpAbUUhbXXGYvgMawZB0jgDcA5Yvy5kLOug2/46 Drnu0Y0q0WoBxUaHzPyD1X1+sRwWPtSCjrzGb6T3B+DJhtF7PTnp0DAs+ gZWErGyyoNJ6gj0lgdg63WDAHo1C4HC6xV4LEY9DsD2E8TGRdiRL/2+Uu fvoc+gNnp7IbctTqsqUp1GU48AF/HESn37ajJl7Ww8s83XJwCv6n/Rwyu Wc8soxrGVCoNx0rTaLysemGQZFFmuVcUK4eW6ONkxk2b+0ej9NFqagzDG g==; X-IronPort-AV: E=McAfee;i="6600,9927,10795"; a="434581748" X-IronPort-AV: E=Sophos;i="6.01,263,1684825200"; d="scan'208";a="434581748" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Aug 2023 23:25:12 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10795"; a="734376741" X-IronPort-AV: E=Sophos;i="6.01,263,1684825200"; d="scan'208";a="734376741" Received: from dmi-pnp-i7.sh.intel.com ([10.239.159.155]) by fmsmga007.fm.intel.com with ESMTP; 07 Aug 2023 23:25:07 -0700 From: Dapeng Mi To: Sean Christopherson , Paolo Bonzini , Peter Zijlstra , Arnaldo Carvalho de Melo , Kan Liang , Like Xu , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter Cc: kvm@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Zhenyu Wang , Zhang Xiong , Lv Zhiyuan , Yang Weijiang , Dapeng Mi , Dapeng Mi Subject: [PATCH RFV v2 00/13] Enable fixed counter 3 and topdown perf metrics for vPMU Date: Tue, 8 Aug 2023 14:30:58 +0800 Message-Id: <20230808063111.1870070-1-dapeng1.mi@linux.intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The TopDown Microarchitecture Analysis (TMA) Method is a structured analysis methodology to identify critical performance bottlenecks in out-of-order processors. The details about topdown metrics support on Intel processors can be found in section "Performance Metrics" of Intel's SDM Volume 3[1]. Kernel enabling code has also been merged, see patchset[2] to learn more about the feature. The TMA method is quite powerful and efficient to help developers to identify the performance bottleneck in the program. The TMA method has been integrated into multiple performance analysis tools, such as perf, Vtune. Developers can leverage TMA method to analyze their program's performance bottleneck easily with these tools and improve their program's performance. TMA method is becoming the most widely used performance analysis method on x86 platform. Currently the TMA method has been supported fairly well on Native, but it's still not supported in Guest environment. Since the environment difference between Host and Guest, even same program may show different performance bottleneck between Guest and Host. Obviously, the most straightforward and best method to profiling Guest performance bottleneck is to run the TMA method in Guest directly. So supporting topdown perf metrics in Guest becomes a real and important requirement and we hope this patchset can mitigate this gap. Like Xu posted a patch series to support guest Topdown[3], the patchset creates a group of topdown metric events in KVM by binding to fixed counter 3 to obtain hardware values and the guest value of PERF_METRICS MSR is assembled based on the count of grouped metric events. This patchset improves Like's proposal, it leverages mature vPMU PMC emulation framework and current perf topdown metric handling logic to support guest topdown metrics feature. In current perf logic, an events group is required to handle the topdown metrics profiling, and the events group couples a slots event which acts events group leader and multiple metric events. To coordinate with the perf topdown metrics handing logic and reduce the code changes in KVM, we choose to follow current mature vPMU PMC emulation framework. The only difference is that we need to create a events group for fixed counter 3 and manipulate FIXED_CTR3 and PERF_METRICS MSRS together instead of a single event and only manipulating FIXED_CTR3 MSR. When guest writes PERF_METRICS MSR at first, KVM would create an event group which couples a slots event and a virtual metrics event. In this event group, slots event claims the fixed counter 3 HW resource and acts as group leader which is required by perf system. The virtual metrics event claims the PERF_METRICS MSR. This event group is just like the perf metrics events group on host and is scheduled by host perf system. In this proposal, the count of slots event is calculated and emulated on host and returned to guest just like other normal counters, but there is a difference for the metrics event processing. KVM doesn't calculate the real count of topdown metrics, it just stores the raw data of PERF_METRICS MSR and directly returnthe stored raw data to guest. Thus, guest can get the real HW PERF_METRICS data and guarantee the calculation accuracy of topdown metrics. Comparing with Like's patchset, this proposal brings two benefits. 1. Reduce the created perf events number Like's patchset needs to create 4 (Ice Lake) or 8 (Sapphire Rapids) metric events, whereas this patchset only needs to create 1 metric event. 2. Increase the accuracy of metric calculation Like's patchset needs to do twice metric count conversion. The first conversion happens on perf system, perf topdown metrics handling logic reads the metric percentage from PERF_METRICS MSR and times with elapsed slots count and obtains the metric count. The second conversion happens on KVM, KVM needs to convert the metric count back to metric percentage by using metric count divide elapsed slots again and then assembles the 4 or 8 metric percentage values to the virtual PERF_METRICS MSR and return to Guest at last. Considering each metric percentage in PERF_METRICS MSR is represented with only 8 bits, the twice conversions (once multiplication and once division) definitely cause accuracy loss in theory. Since this patchset directly returns the raw data of PERF_METRICS MSR to guest, it won't have any accuracy loss. The patchset is rebased on latest kvm-x86/next branch and it is tested on both Host and Guest (SPR Platform) with below perf commands. The 'foo' is a backend-bound benchmark. We can see the output of perf commands are quite close between host and guest. 1. perf stat ./foo Host outputs: Performance counter stats for '/home/sdp/work/foo/foo': 26,525.25 msec task-clock # 1.000 CPUs utilized 9 context-switches # 0.339 /sec 2 cpu-migrations # 0.075 /sec 51 page-faults # 1.923 /sec 125,330,033,745 cycles # 4.725 GHz 238,172,965,287 instructions # 1.90 insn per cycle 44,904,300,430 branches # 1.693 G/sec 69,299,003 branch-misses # 0.15% of all branches 751,979,445,222 TOPDOWN.SLOTS # 59.2 % tma_backend_bound # 38.0 % tma_retiring # 0.8 % tma_bad_speculation # 1.9 % tma_frontend_bound 286,047,083,084 topdown-retiring 14,744,695,003 topdown-fe-bound 445,289,789,131 topdown-be-bound 5,897,878,000 topdown-bad-spec 138,674,397 INT_MISC.UOP_DROPPING # 5.228 M/sec 26.528600835 seconds time elapsed 26.527849000 seconds user 0.000000000 seconds sys Guest outputs: Performance counter stats for '/home/pnp/foo/foo': 29,051.43 msec task-clock # 1.000 CPUs utilized 10 context-switches # 0.344 /sec 0 cpu-migrations # 0.000 /sec 51 page-faults # 1.756 /sec 125,337,801,996 cycles # 4.314 GHz 238,139,676,030 instructions # 1.90 insn per cycle 44,897,906,380 branches # 1.545 G/sec 69,402,326 branch-misses # 0.15% of all branches 752,022,710,490 TOPDOWN.SLOTS # 58.4 % tma_backend_bound # 37.6 % tma_retiring # 1.2 % tma_bad_speculation # 2.7 % tma_frontend_bound 283,114,432,184 topdown-retiring 20,643,760,680 topdown-fe-bound 439,417,191,619 topdown-be-bound 8,847,326,005 topdown-bad-spec 138,873,309 INT_MISC.UOP_DROPPING # 4.780 M/sec 29.058833449 seconds time elapsed 29.048761000 seconds user 0.004003000 seconds sys 2. perf stat -e slots ./foo Host outputs: Performance counter stats for '/home/sdp/work/foo/foo': 713,292,346,950 slots 25.472861484 seconds time elapsed 25.470978000 seconds user 0.000000000 seconds sys Guest outputs: Performance counter stats for '/home/pnp/foo/foo': 713,286,331,824 slots 25.264007882 seconds time elapsed 25.259790000 seconds user 0.004002000 seconds sys 3. echo 0 > /proc/sys/kernel/nmi_watchdog echo 25 > /proc/sys/kernel/perf_cpu_time_max_percent echo 100000 > /proc/sys/kernel/perf_event_max_sample_rate echo 0 > /proc/sys/kernel/perf_cpu_time_max_percent perf record -e slots ./foo && perf report Host outputs: # Total Lost Samples: 0 # # Samples: 109K of event 'slots' # Event count (approx.): 715723903347 # # Overhead Command Shared Object Symbol # ........ ....... ................ .................................. # 74.83% foo libc.so.6 [.] __random 7.22% foo foo [.] qux 7.07% foo libc.so.6 [.] __random_r 5.40% foo foo [.] main 1.82% foo foo [.] bar 1.75% foo foo [.] random@plt 1.73% foo foo [.] foo 0.02% foo [kernel.vmlinux] [k] arch_asym_cpu_priority Guest outputs: # Total Lost Samples: 0 # # Samples: 7K of event 'slots' # Event count (approx.): 24532005986 # # Overhead Command Shared Object Symbol # ........ ....... ................ .................... # 75.21% foo libc.so.6 [.] __random 7.19% foo libc.so.6 [.] __random_r 7.12% foo foo [.] qux 5.21% foo foo [.] main 1.90% foo foo [.] foo 1.81% foo foo [.] bar 1.56% foo foo [.] random@plt 0.00% perf-ex [kernel.vmlinux] [k] native_write_msr To support the guest topdown metrics feature, we have to do several fundamental changes for perf system and vPMU code, we tried to avoid these changes AMAP, but it seems it's inevitable. If you have any idea, please suggest. The fundamental changes: 1. perf/core: Add function perf_event_create_group_kernel_counters() Add a new API to create group events from kernel space 2. perf/core: Add new function perf_event_topdown_metrics() Add a new API to update topdown metrics values 3. perf/x86/intel: Handle KVM virtual metrics event in perf system Add virtual metrics event processing logic in topdown metrics processing code 4. KVM: x86/pmu: Extend pmc_reprogram_counter() to create group events Extend pmc_reprogram_counter() to be capable to create group events instead of just single event References: [1]: Intel 64 and IA-32 Architectures Software Developer Manual Combined Volumes: 1, 2A, 2B, 2C, 2D, 3A, 3B, 3C, 3D, and 4 https://cdrdv2.intel.com/v1/dl/getContent/671200 [2]: perf/x86/intel: Support TopDown metrics on Ice Lake https://lwn.net/ml/linux-kernel/20191203141212.7704-1-kan.liang@linux.intel.com/ [3]: KVM: x86/pmu: Enable Fixed Counter3 and Topdown Perf Metrics https://lwn.net/ml/linux-kernel/20221212125844.41157-1-likexu@tencent.com/ Dapeng Mi (13): KVM: x86/pmu: Add Intel CPUID-hinted TopDown slots event KVM: x86/pmu: Support PMU fixed counter 3 perf/core: Add function perf_event_group_leader_check() perf/core: Add function perf_event_move_group() perf/core: Add function perf_event_create_group_kernel_counters() perf/x86: Fix typos and inconsistent indents in perf_event header perf/x86: Add constraint for guest perf metrics event perf/core: Add new function perf_event_topdown_metrics() perf/x86/intel: Handle KVM virtual metrics event in perf system KVM: x86/pmu: Extend pmc_reprogram_counter() to create group events KVM: x86/pmu: Support topdown perf metrics feature KVM: x86/pmu: Handle PERF_METRICS overflow KVM: x86/pmu: Expose Topdown in MSR_IA32_PERF_CAPABILITIES arch/x86/events/intel/core.c | 72 +++++-- arch/x86/events/perf_event.h | 10 +- arch/x86/include/asm/kvm_host.h | 19 +- arch/x86/include/asm/perf_event.h | 21 +- arch/x86/kvm/pmu.c | 142 +++++++++++-- arch/x86/kvm/pmu.h | 50 ++++- arch/x86/kvm/svm/pmu.c | 2 + arch/x86/kvm/vmx/capabilities.h | 1 + arch/x86/kvm/vmx/pmu_intel.c | 67 ++++++ arch/x86/kvm/vmx/vmx.c | 2 + arch/x86/kvm/vmx/vmx.h | 5 + arch/x86/kvm/x86.c | 5 +- include/linux/perf_event.h | 19 ++ kernel/events/core.c | 326 ++++++++++++++++++++---------- 14 files changed, 590 insertions(+), 151 deletions(-) base-commit: 240f736891887939571854bd6d734b6c9291f22e