Re: [PATCH v4 10/17] perf pmu-events: Hide pmu_events_map

[John Garry <john.garry@huawei.com>]

On 04/08/2022 23:18, Ian Rogers wrote:
> Move usage of the table to pmu-events.c so it may be hidden. By
> abstracting the table the implementation can later be changed.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>   tools/perf/pmu-events/empty-pmu-events.c |  81 ++++++++-
>   tools/perf/pmu-events/jevents.py         |  81 ++++++++-
>   tools/perf/pmu-events/pmu-events.h       |  29 +--
>   tools/perf/tests/pmu-events.c            | 218 +++++++++++------------
>   tools/perf/util/metricgroup.c            |  15 +-
>   tools/perf/util/pmu.c                    |  34 +---
>   tools/perf/util/pmu.h                    |   2 +-
>   7 files changed, 280 insertions(+), 180 deletions(-)
> 
> diff --git a/tools/perf/pmu-events/empty-pmu-events.c b/tools/perf/pmu-events/empty-pmu-events.c
> index 216ea0482c37..8ef75aff996c 100644
> --- a/tools/perf/pmu-events/empty-pmu-events.c
> +++ b/tools/perf/pmu-events/empty-pmu-events.c
> @@ -6,6 +6,8 @@
>    * The test cpu/soc is provided for testing.
>    */
>   #include "pmu-events/pmu-events.h"
> +#include "util/header.h"
> +#include "util/pmu.h"
>   #include <string.h>
>   #include <stddef.h>
>   
> @@ -110,7 +112,26 @@ static const struct pmu_event pme_test_soc_cpu[] = {
>   	},
>   };
>   
> -const struct pmu_events_map pmu_events_map[] = {
> +
> +/*
> + * Map a CPU to its table of PMU events. The CPU is identified by the
> + * cpuid field, which is an arch-specific identifier for the CPU.
> + * The identifier specified in tools/perf/pmu-events/arch/xxx/mapfile
> + * must match the get_cpuid_str() in tools/perf/arch/xxx/util/header.c)
> + *
> + * The  cpuid can contain any character other than the comma.
> + */
> +struct pmu_events_map {
> +	const char *arch;
> +	const char *cpuid;
> +	const struct pmu_event *table;
> +};
> +
> +/*
> + * Global table mapping each known CPU for the architecture to its
> + * table of PMU events.
> + */
> +static const struct pmu_events_map pmu_events_map[] = {
>   	{
>   		.arch = "testarch",
>   		.cpuid = "testcpu",
> @@ -162,6 +183,62 @@ static const struct pmu_sys_events pmu_sys_event_tables[] = {
>   	},
>   };
>   
> +const struct pmu_event *perf_pmu__find_table(struct perf_pmu *pmu)
> +{
> +	const struct pmu_event *table = NULL;
> +	char *cpuid = perf_pmu__getcpuid(pmu);
> +	int i;
> +
> +	/* on some platforms which uses cpus map, cpuid can be NULL for
> +	 * PMUs other than CORE PMUs.
> +	 */
> +	if (!cpuid)
> +		return NULL;
> +
> +	i = 0;
> +	for (;;) {
> +		const struct pmu_events_map *map = &pmu_events_map[i++];
> +
> +		if (!map->table)
> +			break;
> +
> +		if (!strcmp_cpuid_str(map->cpuid, cpuid)) {
> +			table = map->table;
> +			break;
> +		}
> +	}
> +	free(cpuid);
> +	return table;
> +}
> +
> +const struct pmu_event *find_core_events_table(const char *arch, const char *cpuid)
> +{
> +	for (const struct pmu_events_map *tables = &pmu_events_map[0];
> +	     tables->table;
> +	     tables++) {
> +		if (!strcmp(tables->arch, arch) && !strcmp_cpuid_str(tables->cpuid, cpuid))
> +			return tables->table;
> +	}
> +	return NULL;
> +}
> +
> +int pmu_for_each_core_event(pmu_event_iter_fn fn, void *data)
> +{
> +	for (const struct pmu_events_map *tables = &pmu_events_map[0];
> +	     tables->table;
> +	     tables++) {
> +		for (const struct pmu_event *pe = &tables->table[0];
> +		     pe->name || pe->metric_group || pe->metric_name;
> +		     pe++) {
> +			int ret = fn(pe, &tables->table[0], data);
> +
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +	return 0;
> +}
> +
>   const struct pmu_event *find_sys_events_table(const char *name)
>   {
>   	for (const struct pmu_sys_events *tables = &pmu_sys_event_tables[0];
> @@ -181,7 +258,7 @@ int pmu_for_each_sys_event(pmu_event_iter_fn fn, void *data)
>   		for (const struct pmu_event *pe = &tables->table[0];
>   		     pe->name || pe->metric_group || pe->metric_name;
>   		     pe++) {
> -			int ret = fn(pe, data);
> +			int ret = fn(pe, &tables->table[0], data);
>   
>   			if (ret)
>   				return ret;
> diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
> index dd21bc9eeeed..e976c5e8e80b 100755
> --- a/tools/perf/pmu-events/jevents.py
> +++ b/tools/perf/pmu-events/jevents.py
> @@ -333,7 +333,27 @@ def process_one_file(parents: Sequence[str], item: os.DirEntry) -> None:
>   
>   def print_mapping_table(archs: Sequence[str]) -> None:
>     """Read the mapfile and generate the struct from cpuid string to event table."""
> -  _args.output_file.write('const struct pmu_events_map pmu_events_map[] = {\n')
> +  _args.output_file.write("""
> +/*
> + * Map a CPU to its table of PMU events. The CPU is identified by the
> + * cpuid field, which is an arch-specific identifier for the CPU.
> + * The identifier specified in tools/perf/pmu-events/arch/xxx/mapfile
> + * must match the get_cpuid_str() in tools/perf/arch/xxx/util/header.c)
> + *
> + * The  cpuid can contain any character other than the comma.
> + */
> +struct pmu_events_map {
> +        const char *arch;
> +        const char *cpuid;
> +        const struct pmu_event *table;
> +};
> +
> +/*
> + * Global table mapping each known CPU for the architecture to its
> + * table of PMU events.
> + */
> +const struct pmu_events_map pmu_events_map[] = {
> +""")
>     for arch in archs:
>       if arch == 'test':
>         _args.output_file.write("""{
> @@ -389,6 +409,61 @@ static const struct pmu_sys_events pmu_sys_event_tables[] = {
>   \t},
>   };
>   
> +const struct pmu_event *perf_pmu__find_table(struct perf_pmu *pmu)
> +{
> +        const struct pmu_event *table = NULL;
> +        char *cpuid = perf_pmu__getcpuid(pmu);

This seems an identical implementation to that in empty-pmu-events.c - 
can we reduce this duplication? Maybe a seperate common c file which can 
be linked in

The indentation seems different also - this version seems to use whitespaces

> +        int i;
> +
> +        /* on some platforms which uses cpus map, cpuid can be NULL for
> +         * PMUs other than CORE PMUs.
> +         */
> +        if (!cpuid)
> +                return NULL;
> +
> +        i = 0;
> +        for (;;) {
> +                const struct pmu_events_map *map = &pmu_events_map[i++];
> +                if (!map->table)
> +                        break;
> +
> +                if (!strcmp_cpuid_str(map->cpuid, cpuid)) {
> +                        table = map->table;
> +                        break;
> +                }
> +        }
> +        free(cpuid);
> +        return table;
> +}