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Message-ID: <00cde6ff-d9d4-4d03-bee7-a67b192896c5@amd.com>
Date: Mon, 8 Dec 2025 14:51:58 +0530
From: Sandipan Das <sandipan.das@....com>
To: Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Benjamin Gray <bgray@...ux.ibm.com>, Caleb Biggers
<caleb.biggers@...el.com>, Edward Baker <edward.baker@...el.com>,
Ingo Molnar <mingo@...hat.com>, James Clark <james.clark@...aro.org>,
Jing Zhang <renyu.zj@...ux.alibaba.com>, Jiri Olsa <jolsa@...nel.org>,
John Garry <john.g.garry@...cle.com>, Leo Yan <leo.yan@....com>,
Namhyung Kim <namhyung@...nel.org>, Perry Taylor <perry.taylor@...el.com>,
Peter Zijlstra <peterz@...radead.org>, Samantha Alt
<samantha.alt@...el.com>, Thomas Falcon <thomas.falcon@...el.com>,
Weilin Wang <weilin.wang@...el.com>, Xu Yang <xu.yang_2@....com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v9 22/48] perf jevents: Add load store breakdown metrics
ldst for AMD
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@...gle.com>
> Reviewed-by: Sandipan Das <sandipan.das@....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(),
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