Re: [PATCH 3/4] perf/x86/intel: Support hybrid PMU with multiple atom uarchs

Zhenyu Wang
2024-08-12T03:26:15Z

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On 2024.08.12 11:18:34 +0800, Mi, Dapeng wrote:
>
> On 8/11/2024 5:55 AM, Peter Zijlstra wrote:
> > On Thu, Aug 08, 2024 at 02:02:09PM +0000, Dapeng Mi wrote:
> >> arch/x86/events/intel/core.c | 24 +++++++++++++++++-------
> >> arch/x86/events/perf_event.h | 18 +++++++++++++++++-
> >> 2 files changed, 34 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> >> index 0c9c2706d4ec..b6429bc009c0 100644
> >> --- a/arch/x86/events/intel/core.c
> >> +++ b/arch/x86/events/intel/core.c
> >> @@ -6218,6 +6227,7 @@ static inline int intel_pmu_v6_addr_offset(int index, bool eventsel)
> >> static const struct { enum hybrid_pmu_type id; char *name; } intel_hybrid_pmu_type_map[] __initconst = {
> >> { hybrid_small, "cpu_atom" },
> >> { hybrid_big, "cpu_core" },
> >> + { hybrid_small2, "cpu_atom2" },
> > This is awfully uninspired and quite terrible. How is one supposed to
> > know which is which? A possibly better naming might be: hybrid_tiny,
> > "cpu_lowpower" or whatever.
>
> We have lots of discussion internally about the naming, but unfortunately
> we can't come to a conclusion. The reason that we select "cpu_atom2" is
> that it's generic enough and won't expose too much model specific
> information, we can reuse it if there are similar platforms in the future.
> But of course I admit the name is indeed uninspired and easy to cause
> confusion.
>
> The other names which I ever discussed are "cpu_lp_soc", "cpu_soc" and
> "cpu_atom_soc", but this name would expose some model specific architecture
> information more or less, not sure which one is better. How is your opinion
> on this?
>

Now I don't like to put 'soc' in name as it's specific for platform design
e.g ARL-H, but pmu actually only cares about cpu type. Maybe "cpu_atom_lp"
is good enough.

>
> >
> >> };
> >>
> >> static __always_inline int intel_pmu_init_hybrid(enum hybrid_pmu_type pmus)
> >> @@ -6250,7 +6260,7 @@ static __always_inline int intel_pmu_init_hybrid(enum hybrid_pmu_type pmus)
> >> 0, x86_pmu_num_counters(&pmu->pmu), 0, 0);
> >>
> >> pmu->intel_cap.capabilities = x86_pmu.intel_cap.capabilities;
> >> - if (pmu->pmu_type & hybrid_small) {
> >> + if (pmu->pmu_type & hybrid_small_all) {
> >> pmu->intel_cap.perf_metrics = 0;
> >> pmu->intel_cap.pebs_output_pt_available = 1;
> >> pmu->mid_ack = true;
> >> diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
> >> index 5d1677844e04..f7b55c909eff 100644
> >> --- a/arch/x86/events/perf_event.h
> >> +++ b/arch/x86/events/perf_event.h
> >> @@ -668,6 +668,13 @@ enum {
> >> #define PERF_PEBS_DATA_SOURCE_GRT_MAX 0x10
> >> #define PERF_PEBS_DATA_SOURCE_GRT_MASK (PERF_PEBS_DATA_SOURCE_GRT_MAX - 1)
> >>
> >> +
> >> +/*
> >> + * CPUID.1AH.EAX[31:0] uniquely identifies the microarchitecture
> >> + * of the core. Bits 31-24 indicates its core type (Core or Atom)
> >> + * and Bits [23:0] indicates the native model ID of the core.
> >> + * Core type and native model ID are defined in below enumerations.
> >> + */
> >> enum hybrid_cpu_type {
> >> HYBRID_INTEL_NONE,
> >> HYBRID_INTEL_ATOM = 0x20,
> >> @@ -676,12 +683,21 @@ enum hybrid_cpu_type {
> >>
> >> #define X86_HYBRID_PMU_ATOM_IDX 0
> >> #define X86_HYBRID_PMU_CORE_IDX 1
> >> +#define X86_HYBRID_PMU_ATOM2_IDX 2
> >> enum hybrid_pmu_type {
> >> not_hybrid,
> >> hybrid_small = BIT(X86_HYBRID_PMU_ATOM_IDX),
> >> hybrid_big = BIT(X86_HYBRID_PMU_CORE_IDX),
> >> + hybrid_small2 = BIT(X86_HYBRID_PMU_ATOM2_IDX),
> >> + /* The belows are only used for matching */
> >> + hybrid_big_small = hybrid_big | hybrid_small,
> >> + hybrid_small_all = hybrid_small | hybrid_small2,
> >> + hybrid_big_small_arl_h = hybrid_big | hybrid_small_all,
> > Same complaint, how about:
> >
> > + hybrid_tiny = BIT(X86_HYBRID_PMU_TINY_IDX),
> > hybrid_big_small = hybrid_big | hybrid_small,
> > + hybrid_small_tiny = hybrid_small | hybrid_tiny,
> > + hybrid_big_small_tiny = hybrid_big_small | hybrid_tiny,
>
> Sure. I would adjust the macro name base on the above discussed final name.
> Thanks.
>
>
> >
> >
> >> +};
> >>
> >> - hybrid_big_small = hybrid_big | hybrid_small, /* only used for matching */
> >> +enum atom_native_id {
> >> + cmt_native_id = 0x2, /* Crestmont */
> >> + skt_native_id = 0x3, /* Skymont */
> >> };
> >>
> >> struct x86_hybrid_pmu {
> >> --
> >> 2.40.1
> >>

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