From: Peter Zijlstra <peterz@infradead.org>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
Ingo Molnar <mingo@kernel.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 22:52:42 +0200 [thread overview]
Message-ID: <20231002205242.GC27267@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <f6b295f2-966c-f566-14c0-dbe02cad2bd2@linux.intel.com>
On Mon, Oct 02, 2023 at 03:50:24PM -0400, Liang, Kan wrote:
> 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")
For some simple cases. I've had plenty experience with situations where
that thing would be completely useless.
That is, at some point the 'all CPUs hard locked up' scenario was
something I ran into a lot (although I can't for the life of me remember
wtf I was doing at the time). All that needs is a single
spin_lock_irqsave() on a common lock (or group of locks, like the
rq->lock). Before you know it, the whole machine is a brick.
That said; if you augment this thing with a bunch of CPUs that have
HPET-NMI and IPI-NMI for backtraces, it might actually be useful.
next prev parent reply other threads:[~2023-10-02 20:53 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
2023-10-02 20:52 ` Peter Zijlstra [this message]
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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