Re: [PATCH 3/4] perf vendor events arm64: Add AmpereOne metrics

[John Garry]

On 04/08/2023 20:59, Ilkka Koskinen wrote:
> Hi John
>
> On Fri, 4 Aug 2023, John Garry wrote:
> > On 03/08/2023 22:13, Ilkka Koskinen wrote:
> > > This patch adds AmpereOne metrics. The metrics also work around
> > > the issue related to some of the events.

Would these events be any metrics added which are not a "Topdown"? I 
guess no, since there are many, but I just don't know.

> > Just curious, are these events/metrics described in some 
> > publically-available document?
>
> I quickly checked that and there are a spreadsheet and a document 
> available, which list the supported PMUs, their events and metrics in 
> the customer connect website but that requires registering.

OK, thanks for the info. I ask is it always worthwhile mentioning a link 
in the changelog if publicly available.


Just a few minor comments:

On 03/08/2023 22:13, Ilkka Koskinen wrote:
> This patch adds AmpereOne metrics. The metrics also work around
> the issue related to some of the events.
>
> Signed-off-by: Ilkka Koskinen <ilkka@xxxxxxxxxxxxxxxxxxxxxx>
> ---
>   .../arch/arm64/ampere/ampereone/metrics.json  | 362 ++++++++++++++++++
>   1 file changed, 362 insertions(+)
>

...

> +    {
> +	"MetricExpr": "CRYPTO_SPEC / OP_SPEC",
> +	"BriefDescription": "Proportion of crypto data processing operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "Crypto mix"
> +    },
> +    {
> +	"MetricExpr": "VFP_SPEC / (duration_time *1000000000)",
> +	"BriefDescription": "Giga-floating point operations per second",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "GFLOPS_ISSUED"
> +    },
> +    {
> +	"MetricExpr": "DP_SPEC / OP_SPEC",
> +	"BriefDescription": "Proportion of integer data processing operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "Integer mix"
> +    },
> +    {
> +	"MetricExpr": "INST_RETIRED / CPU_CYCLES",
> +	"BriefDescription": "Instructions per cycle",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "IPC"
> +    },
> +    {
> +	"MetricExpr": "LD_SPEC / OP_SPEC",
> +	"BriefDescription": "Proportion of load operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "Load mix"
> +    },
> +    {
> +	"MetricExpr": "LDST_SPEC/ OP_SPEC",

mega nit: missing whitespace before '/'

> +	"BriefDescription": "Proportion of load & store operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "Load-store mix"
> +    },
> +    {
> +	"MetricExpr": "INST_RETIRED / (duration_time * 1000000)",

I think that we may use 1e6 here for shorthand - it helps avoid mistakes 
with too few or many '0's :)

> +	"BriefDescription": "Millions of instructions per second",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "MIPS_RETIRED"
> +    },
> +    {
> +	"MetricExpr": "INST_SPEC / (duration_time * 1000000)",
> +	"BriefDescription": "Millions of instructions per second",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "MIPS_UTILIZATION"
> +    },
> +    {
> +	"MetricExpr": "PC_WRITE_SPEC / OP_SPEC",
> +	"BriefDescription": "Proportion of software change of PC operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "PC write mix"
> +    },
> +    {
> +	"MetricExpr": "ST_SPEC / OP_SPEC",
> +	"BriefDescription": "Proportion of store operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "Store mix"
> +    },
> +    {
> +	"MetricExpr": "VFP_SPEC / OP_SPEC",
> +	"BriefDescription": "Proportion of FP operations",
> +	"MetricGroup": "Instruction",
> +	"MetricName": "VFP mix"
> +    },
> +    {
> +	"MetricExpr": "1 - (OP_RETIRED/ (CPU_CYCLES * 4))",
> +	"BriefDescription": "Proportion of slots lost",
> +	"MetricGroup": "Speculation / TDA",
> +	"MetricName": "CPU lost"
> +    },
> +    {
> +	"MetricExpr": "OP_RETIRED/ (CPU_CYCLES * 4)",
> +	"BriefDescription": "Proportion of slots retiring",
> +	"MetricGroup": "Speculation / TDA",
> +	"MetricName": "CPU utilization"
> +    },
> +    {
> +	"MetricExpr": "OP_RETIRED - OP_SPEC",
> +	"BriefDescription": "Operations lost due to misspeculation",
> +	"MetricGroup": "Speculation / TDA",
> +	"MetricName": "Operations lost"
> +    },
> +    {
> +	"MetricExpr": "1 - (OP_RETIRED / OP_SPEC)",
> +	"BriefDescription": "Proportion of operations lost",
> +	"MetricGroup": "Speculation / TDA",
> +	"MetricName": "Operations lost (ratio)"
> +    },
> +    {
> +	"MetricExpr": "OP_RETIRED / OP_SPEC",
> +	"BriefDescription": "Proportion of operations retired",
> +	"MetricGroup": "Speculation / TDA",
> +	"MetricName": "Operations retired"
> +    },
> +    {
> +	"MetricExpr": "STALL_BACKEND_CACHE / CPU_CYCLES",
> +	"BriefDescription": "Proportion of cycles stalled and no operations 
issued to backend and cache miss",
> +	"MetricGroup": "Stall",
> +	"MetricName": "Stall backend cache cycles"
> +    },
> +    {
> +	"MetricExpr": "STALL_BACKEND_RESOURCE / CPU_CYCLES",
> +	"BriefDescription": "Proportion of cycles stalled and no operations 
issued to backend and resource full",
> +	"MetricGroup": "Stall",
> +	"MetricName": "Stall backend resource cycles"
> +    },
> +    {
> +	"MetricExpr": "STALL_BACKEND_TLB / CPU_CYCLES",
> +	"BriefDescription": "Proportion of cycles stalled and no operations 
issued to backend and TLB miss",
> +	"MetricGroup": "Stall",
> +	"MetricName": "Stall backend tlb cycles"
> +    },
> +    {
> +	"MetricExpr": "STALL_FRONTEND_CACHE / CPU_CYCLES",
> +	"BriefDescription": "Proportion of cycles stalled and no ops 
delivered from frontend and cache miss",
> +	"MetricGroup": "Stall",
> +	"MetricName": "Stall frontend cache cycles"
> +    },
> +    {
> +	"MetricExpr": "STALL_FRONTEND_TLB / CPU_CYCLES",
> +	"BriefDescription": "Proportion of cycles stalled and no ops 
delivered from frontend and TLB miss",
> +	"MetricGroup": "Stall",
> +	"MetricName": "Stall frontend tlb cycles"
> +    },
> +    {
> +	"MetricExpr": "DTLB_WALK / L1D_TLB",
> +	"BriefDescription": "D-side walk per d-side translation request",
> +	"MetricGroup": "TLB",
> +	"MetricName": "DTLB walks"
> +    },
> +    {
> +	"MetricExpr": "ITLB_WALK / L1I_TLB",
> +	"BriefDescription": "I-side walk per i-side translation request",
> +	"MetricGroup": "TLB",
> +	"MetricName": "ITLB walks"
> +    },
> +    {
> +        "MetricExpr": "STALL_SLOT_BACKEND / (CPU_CYCLES * 4)",
> +        "BriefDescription": "Fraction of slots backend bound",
> +        "MetricGroup": "TopDownL1",

@Ian, should this be "Default;TopDownL1"?

> +        "MetricName": "backend"

How about use consistent names with other other archs and arm64 
platforms, like "backend_bound"? I did not check all names, but please 
consider this.

If 'perf topdown' is ever supported for arm64, we would prob rely on 
metricgroups, so would need use a fixed standard name here. Note that 
x86 uses custom kernel events for this instead.

> +    },
> +    {
> +        "MetricExpr": "1 - (retiring + lost + backend)",
> +        "BriefDescription": "Fraction of slots frontend bound",
> +        "MetricGroup": "TopDownL1",
> +        "MetricName": "frontend"

As above, it would be "frontend_bound"

> +    },
> +    {
> +        "MetricExpr": "((OP_SPEC - OP_RETIRED) / (CPU_CYCLES * 4))",
> +        "BriefDescription": "Fraction of slots lost due to 
misspeculation",
> +        "MetricGroup": "TopDownL1",
> +        "MetricName": "lost"
> +    },
> +    {