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From: "Liang, Kan" <kan.liang@linux.intel.com>
To: Sean Christopherson <seanjc@google.com>, Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Dapeng Mi <dapeng1.mi@linux.intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Like Xu <likexu@tencent.com>, Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	kvm@vger.kernel.org, linux-perf-users@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Zhenyu Wang <zhenyuw@linux.intel.com>,
	Zhang Xiong <xiong.y.zhang@intel.com>,
	Lv Zhiyuan <zhiyuan.lv@intel.com>,
	Yang Weijiang <weijiang.yang@intel.com>,
	Dapeng Mi <dapeng1.mi@intel.com>,
	Jim Mattson <jmattson@google.com>,
	David Dunn <daviddunn@google.com>,
	Mingwei Zhang <mizhang@google.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [Patch v4 07/13] perf/x86: Add constraint for guest perf metrics event
Date: Mon, 2 Oct 2023 15:50:24 -0400	[thread overview]
Message-ID: <f6b295f2-966c-f566-14c0-dbe02cad2bd2@linux.intel.com> (raw)
In-Reply-To: <ZRroQg6flyGBtZTG@google.com>



On 2023-10-02 11:56 a.m., Sean Christopherson wrote:
> I am completely ok with either approach, but I am not ok with being nak'd on both.
> Because unless there's a magical third option lurking, those two options are the
> only ways for KVM to provide a vPMU that meets the requirements for slice-of-hardware
> use cases.

It may be doable to introduce a knob to enable/disable the "CPU-pinned"
capability of perf_event. If the capability is disabled, the KVM doesn't
need to worry about the counters being gone without notification, since
the "task pinned" has the highest priority at the moment.

It should also keeps the flexibility that sometimes the host wants to
profile the guest.

Now, the NMI watchdog is using a "CPU-pinned" event. But I think it can
be replaced by the buddy system, commit 1f423c905a6b
("watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs")

Thanks,
Kan

  reply	other threads:[~2023-10-02 19:50 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-27  3:31 [Patch v4 00/13] Enable fixed counter 3 and topdown perf metrics for vPMU Dapeng Mi
2023-09-27  3:31 ` [Patch v4 01/13] KVM: x86/pmu: Add Intel CPUID-hinted TopDown slots event Dapeng Mi
2023-09-27  3:31 ` [Patch v4 02/13] KVM: x86/pmu: Support PMU fixed counter 3 Dapeng Mi
2023-09-27  3:31 ` [Patch v4 03/13] perf/core: Add function perf_event_group_leader_check() Dapeng Mi
2023-09-27  3:31 ` [Patch v4 04/13] perf/core: Add function perf_event_move_group() Dapeng Mi
2023-09-27  3:31 ` [Patch v4 05/13] perf/core: Add *group_leader for perf_event_create_group_kernel_counters() Dapeng Mi
2023-09-27  3:31 ` [Patch v4 06/13] perf/x86: Fix typos and inconsistent indents in perf_event header Dapeng Mi
2023-09-27  3:31 ` [Patch v4 07/13] perf/x86: Add constraint for guest perf metrics event Dapeng Mi
2023-09-27 11:33   ` Peter Zijlstra
2023-09-27 17:27     ` Sean Christopherson
2023-09-28  9:24       ` Mi, Dapeng
2023-09-29 11:53       ` Peter Zijlstra
2023-09-29 15:20         ` Ravi Bangoria
2023-10-02 12:29           ` Peter Zijlstra
2023-10-03  6:36             ` Ravi Bangoria
2023-09-29 15:46         ` Sean Christopherson
2023-09-30  3:29           ` Jim Mattson
2023-10-01  0:31             ` Namhyung Kim
2023-10-02 11:57           ` Peter Zijlstra
2023-10-02 13:30             ` Ingo Molnar
2023-10-02 15:23               ` David Dunn
2023-10-02 19:02                 ` Mingwei Zhang
2023-10-02 15:56               ` Sean Christopherson
2023-10-02 19:50                 ` Liang, Kan [this message]
2023-10-02 20:52                   ` Peter Zijlstra
2023-10-02 20:40                 ` Peter Zijlstra
2023-10-03  0:56                   ` Sean Christopherson
2023-10-03  8:16                     ` Peter Zijlstra
2023-10-03 15:23                       ` Sean Christopherson
2023-10-03 18:21                         ` Jim Mattson
2023-10-04 11:32                           ` Peter Zijlstra
2023-10-04 11:21                         ` Peter Zijlstra
2023-10-04 19:51                           ` Mingwei Zhang
2023-10-04 21:50                             ` Sean Christopherson
2023-10-04 22:05                               ` Sean Christopherson
2023-10-08 10:04                                 ` Like Xu
2023-10-09 17:03                                   ` Manali Shukla
2023-10-11 14:15                                     ` Peter Zijlstra
2023-10-17 10:24                                       ` Manali Shukla
2023-10-17 16:58                                         ` Mingwei Zhang
2023-10-18  0:01                                           ` Mingwei Zhang
2023-10-11 14:20                               ` Peter Zijlstra
2023-10-13 17:02                                 ` Sean Christopherson
2023-10-03 17:31                       ` Manali Shukla
2023-10-03 22:02                     ` Mingwei Zhang
2023-10-04 20:43                       ` Sean Christopherson
2023-09-27  3:31 ` [Patch v4 08/13] perf/core: Add new function perf_event_topdown_metrics() Dapeng Mi
2023-09-27  3:31 ` [Patch v4 09/13] perf/x86/intel: Handle KVM virtual metrics event in perf system Dapeng Mi
2023-09-27  3:31 ` [Patch v4 10/13] KVM: x86/pmu: Extend pmc_reprogram_counter() to create group events Dapeng Mi
2023-09-27  3:31 ` [Patch v4 11/13] KVM: x86/pmu: Support topdown perf metrics feature Dapeng Mi
2023-09-27  3:31 ` [Patch v4 12/13] KVM: x86/pmu: Handle PERF_METRICS overflow Dapeng Mi
2023-09-27  3:31 ` [Patch v4 13/13] KVM: x86/pmu: Expose Topdown in MSR_IA32_PERF_CAPABILITIES Dapeng Mi

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