Re: [PATCH v9 22/48] perf jevents: Add load store breakdown metrics ldst for AMD

[Sandipan Das <sandipan.das@amd.com>]

On 12/2/2025 11:20 PM, Ian Rogers wrote:
> Give breakdown of number of instructions. Use the counter mask (cmask)
> to show the number of cycles taken to retire the instructions.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> Reviewed-by: Sandipan Das <sandipan.das@amd.com>
> ---
>  tools/perf/pmu-events/amd_metrics.py | 75 ++++++++++++++++++++++++++++
>  1 file changed, 75 insertions(+)
> 
> diff --git a/tools/perf/pmu-events/amd_metrics.py b/tools/perf/pmu-events/amd_metrics.py
> index 6542c334a82b..1611d0e50d03 100755
> --- a/tools/perf/pmu-events/amd_metrics.py
> +++ b/tools/perf/pmu-events/amd_metrics.py
> @@ -279,6 +279,80 @@ def AmdItlb():
>      ], description="Instruction TLB breakdown")
>  
>  
> +def AmdLdSt() -> MetricGroup:
> +    ldst_ld = Event("ls_dispatch.ld_dispatch")
> +    ldst_st = Event("ls_dispatch.store_dispatch")
> +    ldst_ldc1 = Event(f"{ldst_ld}/cmask=1/")
> +    ldst_stc1 = Event(f"{ldst_st}/cmask=1/")
> +    ldst_ldc2 = Event(f"{ldst_ld}/cmask=2/")
> +    ldst_stc2 = Event(f"{ldst_st}/cmask=2/")
> +    ldst_ldc3 = Event(f"{ldst_ld}/cmask=3/")
> +    ldst_stc3 = Event(f"{ldst_st}/cmask=3/")
> +    ldst_cyc = Event("ls_not_halted_cyc")
> +
> +    ld_rate = d_ratio(ldst_ld, interval_sec)
> +    st_rate = d_ratio(ldst_st, interval_sec)
> +
> +    ld_v1 = max(ldst_ldc1 - ldst_ldc2, 0)
> +    ld_v2 = max(ldst_ldc2 - ldst_ldc3, 0)
> +    ld_v3 = ldst_ldc3
> +
> +    st_v1 = max(ldst_stc1 - ldst_stc2, 0)
> +    st_v2 = max(ldst_stc2 - ldst_stc3, 0)
> +    st_v3 = ldst_stc3
> +
> +    return MetricGroup("lpm_ldst", [
> +        MetricGroup("lpm_ldst_total", [
> +            Metric("lpm_ldst_total_ld", "Number of loads dispatched per second.",
> +                   ld_rate, "insns/sec"),
> +            Metric("lpm_ldst_total_st", "Number of stores dispatched per second.",
> +                   st_rate, "insns/sec"),
> +        ]),
> +        MetricGroup("lpm_ldst_percent_insn", [
> +            Metric("lpm_ldst_percent_insn_ld",
> +                   "Load instructions as a percentage of all instructions.",
> +                   d_ratio(ldst_ld, ins), "100%"),
> +            Metric("lpm_ldst_percent_insn_st",
> +                   "Store instructions as a percentage of all instructions.",
> +                   d_ratio(ldst_st, ins), "100%"),
> +        ]),
> +        MetricGroup("lpm_ldst_ret_loads_per_cycle", [
> +            Metric(
> +                "lpm_ldst_ret_loads_per_cycle_1",
> +                "Load instructions retiring in 1 cycle as a percentage of all "
> +                "unhalted cycles.", d_ratio(ld_v1, ldst_cyc), "100%"),
> +            Metric(
> +                "lpm_ldst_ret_loads_per_cycle_2",
> +                "Load instructions retiring in 2 cycles as a percentage of all "
> +                "unhalted cycles.", d_ratio(ld_v2, ldst_cyc), "100%"),
> +            Metric(
> +                "lpm_ldst_ret_loads_per_cycle_3",
> +                "Load instructions retiring in 3 or more cycles as a percentage"
> +                "of all unhalted cycles.", d_ratio(ld_v3, ldst_cyc), "100%"),
> +        ]),
> +        MetricGroup("lpm_ldst_ret_stores_per_cycle", [
> +            Metric(
> +                "lpm_ldst_ret_stores_per_cycle_1",
> +                "Store instructions retiring in 1 cycle as a percentage of all "
> +                "unhalted cycles.", d_ratio(st_v1, ldst_cyc), "100%"),
> +            Metric(
> +                "lpm_ldst_ret_stores_per_cycle_2",
> +                "Store instructions retiring in 2 cycles as a percentage of all "
> +                "unhalted cycles.", d_ratio(st_v2, ldst_cyc), "100%"),
> +            Metric(
> +                "lpm_ldst_ret_stores_per_cycle_3",
> +                "Store instructions retiring in 3 or more cycles as a percentage"
> +                "of all unhalted cycles.", d_ratio(st_v3, ldst_cyc), "100%"),
> +        ]),

A subset of dispatched loads and stores do not retire. So PMCx029, which is used by
ldst_ld and ldst_st above, does not provide the number of retired loads and stores.
There is currently no event which counts retired loads and stores :(

> +        MetricGroup("lpm_ldst_insn_bt", [
> +            Metric("lpm_ldst_insn_bt_ld", "Number of instructions between loads.",
> +                   d_ratio(ins, ldst_ld), "insns"),
> +            Metric("lpm_ldst_insn_bt_st", "Number of instructions between stores.",
> +                   d_ratio(ins, ldst_st), "insns"),
> +        ])
> +    ], description="Breakdown of load/store instructions")
> +
> +
>  def AmdUpc() -> Metric:
>      ops = Event("ex_ret_ops", "ex_ret_cops")
>      upc = d_ratio(ops, smt_cycles)
> @@ -365,6 +439,7 @@ def main() -> None:
>          AmdBr(),
>          AmdDtlb(),
>          AmdItlb(),
> +        AmdLdSt(),
>          AmdUpc(),
>          Idle(),
>          Rapl(),