Re: [PATCH v3 1/2] perf arm-spe: Prepare for adding data source packet implementations for other cores

[Leo Yan <leo.yan@arm.com>]

Hi Ilkka,

This is a good refactoring for me.  Just several minor comments.

On Wed, Nov 06, 2024 at 07:37:39PM +0000, Ilkka Koskinen wrote:
> 
> Split Data Source Packet handling to prepare adding support for
> other implementations.
> 
> Signed-off-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
> ---
>  tools/perf/util/arm-spe.c | 65 ++++++++++++++++++++++++---------------
>  1 file changed, 40 insertions(+), 25 deletions(-)
> 
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index dbf13f47879c..b222557cc27a 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -103,6 +103,18 @@ struct arm_spe_queue {
>         u32                             flags;
>  };
> 
> +struct data_src {
> +       struct midr_range midr_range;
> +       void (*ds_synth)(const struct arm_spe_record *record,
> +                        union perf_mem_data_src *data_src);
> +};

The naming is a bit mess. The data structure and the parameter both
are called "data_src", though this will not cause building issue.

How about rename the structure "data_src" to "data_source_handle" or
"data_source_class"?

For the "midr_range" field, I'd like to change it to a pointer:

  struct midr_range *midr_range;

Please see below comments, which will present the reason for defining
it as a pointer.

> +
> +#define DS(range, func)                        \
> +       {                                               \
> +               .midr_range = range,                    \
> +               .ds_synth = arm_spe__synth_##func,      \
> +       }
> +
>  static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
>                          unsigned char *buf, size_t len)
>  {
> @@ -430,19 +442,6 @@ static int arm_spe__synth_instruction_sample(struct arm_spe_queue *speq,
>         return arm_spe_deliver_synth_event(spe, speq, event, &sample);
>  }
> 
> -static const struct midr_range common_ds_encoding_cpus[] = {
> -       MIDR_ALL_VERSIONS(MIDR_CORTEX_A720),
> -       MIDR_ALL_VERSIONS(MIDR_CORTEX_A725),
> -       MIDR_ALL_VERSIONS(MIDR_CORTEX_X1C),
> -       MIDR_ALL_VERSIONS(MIDR_CORTEX_X3),
> -       MIDR_ALL_VERSIONS(MIDR_CORTEX_X925),
> -       MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1),
> -       MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2),
> -       MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V1),
> -       MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V2),
> -       {},
> -};

We can keep this data structure.  For Ampere CPUs, you can add a new
data structure:

  static const struct midr_range ampereone_ds_encoding_cpus[] = {
      MIDR_ALL_VERSIONS(MIDR_AMPERE1A),
      {},
  };

> -
>  static void arm_spe__sample_flags(struct arm_spe_queue *speq)
>  {
>         const struct arm_spe_record *record = &speq->decoder->record;
> @@ -532,6 +531,19 @@ static void arm_spe__synth_data_source_common(const struct arm_spe_record *recor
>         }
>  }
> 
> +static const struct data_src data_sources[] = {
> +       DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_A720), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_A725), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_X1C), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_X3), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_X925), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V1), data_source_common),
> +       DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V2), data_source_common),
> +       {},
> +};
> +

As a result, we can simplify the structure as:

  static const struct data_src data_sources[] = {
         DS(common_ds_encoding_cpus, data_source_common),
         DS(ampereone_ds_encoding_cpus, data_source_ampereone),
  };

>  static void arm_spe__synth_memory_level(const struct arm_spe_record *record,
>                                         union perf_mem_data_src *data_src)
>  {
> @@ -555,12 +567,14 @@ static void arm_spe__synth_memory_level(const struct arm_spe_record *record,
>                 data_src->mem_lvl |= PERF_MEM_LVL_REM_CCE1;
>  }
> 
> -static bool arm_spe__is_common_ds_encoding(struct arm_spe_queue *speq)
> +static bool arm_spe__synth_ds(struct arm_spe_queue *speq,
> +                             const struct arm_spe_record *record,
> +                             union perf_mem_data_src *data_src)
>  {
>         struct arm_spe *spe = speq->spe;
> -       bool is_in_cpu_list;
> +       const struct data_src *src = data_sources;
>         u64 *metadata = NULL;
> -       u64 midr = 0;
> +       u64 midr;
> 
>         /* Metadata version 1 assumes all CPUs are the same (old behavior) */
>         if (spe->metadata_ver == 1) {
> @@ -592,18 +606,21 @@ static bool arm_spe__is_common_ds_encoding(struct arm_spe_queue *speq)
>                 midr = metadata[ARM_SPE_CPU_MIDR];
>         }
> 
> -       is_in_cpu_list = is_midr_in_range_list(midr, common_ds_encoding_cpus);
> -       if (is_in_cpu_list)
> -               return true;
> -       else
> -               return false;
> +       while (src->midr_range.model) {
> +               if (is_midr_in_range(midr, &src->midr_range)) {
> +                       src->ds_synth(record, data_src);
> +                       return true;
> +               }
> +               src++;
> +       }

Here we can traverse the 'data_sources' array:

          for (i = 0; i < ARRAY_SIZE(data_sources); i++) {
               if (is_midr_in_range(midr, data_sources[i]->midr_range)) {
                   ...
               }
          }

Thanks,
Leo

> +
> +       return false;
>  }
> 
>  static u64 arm_spe__synth_data_source(struct arm_spe_queue *speq,
>                                       const struct arm_spe_record *record)
>  {
>         union perf_mem_data_src data_src = { .mem_op = PERF_MEM_OP_NA };
> -       bool is_common = arm_spe__is_common_ds_encoding(speq);
> 
>         if (record->op & ARM_SPE_OP_LD)
>                 data_src.mem_op = PERF_MEM_OP_LOAD;
> @@ -612,9 +629,7 @@ static u64 arm_spe__synth_data_source(struct arm_spe_queue *speq,
>         else
>                 return 0;
> 
> -       if (is_common)
> -               arm_spe__synth_data_source_common(record, &data_src);
> -       else
> +       if (!arm_spe__synth_ds(speq, record, &data_src))
>                 arm_spe__synth_memory_level(record, &data_src);
> 
>         if (record->type & (ARM_SPE_TLB_ACCESS | ARM_SPE_TLB_MISS)) {
> --
> 2.47.0
> 
>