Messages in this thread | | | Subject | Re: [PATCH V2 16/25] perf/x86: Register hybrid PMUs | From | "Liang, Kan" <> | Date | Thu, 11 Mar 2021 10:41:00 -0500 |
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On 3/11/2021 7:34 AM, Peter Zijlstra wrote: > On Wed, Mar 10, 2021 at 08:37:52AM -0800, kan.liang@linux.intel.com wrote: >> @@ -2092,9 +2105,37 @@ static int __init init_hw_perf_events(void) >> if (err) >> goto out1; >> >> - err = perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW); >> - if (err) >> - goto out2; >> + if (!is_hybrid()) { >> + err = perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW); >> + if (err) >> + goto out2; >> + } else { >> + u8 cpu_type = get_hybrid_cpu_type(smp_processor_id()); >> + struct x86_hybrid_pmu *hybrid_pmu; >> + int i; >> + >> + for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) { >> + hybrid_pmu = &x86_pmu.hybrid_pmu[i]; >> + >> + hybrid_pmu->pmu = pmu; >> + hybrid_pmu->pmu.type = -1; >> + hybrid_pmu->pmu.attr_update = x86_pmu.attr_update; >> + hybrid_pmu->pmu.capabilities |= PERF_PMU_CAP_HETEROGENEOUS_CPUS; >> + >> + /* Only register the PMU for the boot CPU */ > > Why ?! > > AFAICT we could register them all here. That instantly fixes that > CPU_STARTING / CPU_DEAD fail elsewhere in this patch.
It's possible that all CPUs of a certain type all offline, but I cannot know the information here, because the boot CPU is the only online CPU. I don't know the status of the other CPUs.
If we unconditionally register all PMUs, users may see a PMU in /sys/devices, but they cannot use it, because there is no available CPU. Is it acceptable that registering an empty PMU?
Thanks, Kan
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