Re: [PATCH v3 16/35] perf pmu: Remove perf_pmu__hybrid_mounted

Liang, Kan
2023-05-26T18:14:16Z

On 2023-05-24 6:18 p.m., Ian Rogers wrote:
> perf_pmu__hybrid_mounted is used to detect whether cpu_core or
> cpu_atom is mounted with a non-empty cpus file by
> pmu_lookup. pmu_lookup will attempt to read the cpus file too and so
> the check can be folded into this.
>
> Checking hybrid_mounted in pmu_is_uncore is redundant as the next
> cpumask read will fail returning false.
>
> Reduce the scope of perf_pmu__find_hybrid_pmu by making it static.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/pmu-hybrid.c | 15 +--------------
> tools/perf/util/pmu-hybrid.h | 3 ---
> tools/perf/util/pmu.c | 26 ++++++++++++++------------
> 3 files changed, 15 insertions(+), 29 deletions(-)
>
> diff --git a/tools/perf/util/pmu-hybrid.c b/tools/perf/util/pmu-hybrid.c
> index bc4cb0738c35..7fe943dd3217 100644
> --- a/tools/perf/util/pmu-hybrid.c
> +++ b/tools/perf/util/pmu-hybrid.c
> @@ -18,20 +18,7 @@
>
> LIST_HEAD(perf_pmu__hybrid_pmus);
>
> -bool perf_pmu__hybrid_mounted(const char *name)
> -{
> - int cpu;
> - char pmu_name[PATH_MAX];
> - struct perf_pmu pmu = {.name = pmu_name};
> -
> - if (strncmp(name, "cpu_", 4))
> - return false;
> -
> - strlcpy(pmu_name, name, sizeof(pmu_name));
> - return perf_pmu__scan_file(&pmu, "cpus", "%u", &cpu) > 0;
> -}
> -
> -struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name)
> +static struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name)
> {
> struct perf_pmu *pmu;
>
> diff --git a/tools/perf/util/pmu-hybrid.h b/tools/perf/util/pmu-hybrid.h
> index 206b94931531..8dbcae935020 100644
> --- a/tools/perf/util/pmu-hybrid.h
> +++ b/tools/perf/util/pmu-hybrid.h
> @@ -13,9 +13,6 @@ extern struct list_head perf_pmu__hybrid_pmus;
> #define perf_pmu__for_each_hybrid_pmu(pmu) \
> list_for_each_entry(pmu, &perf_pmu__hybrid_pmus, hybrid_list)
>
> -bool perf_pmu__hybrid_mounted(const char *name);
> -
> -struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name);
> bool perf_pmu__is_hybrid(const char *name);
>
> static inline int perf_pmu__hybrid_pmu_num(void)
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index cd94abe7a87a..e9f3e6a777c0 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -617,9 +617,6 @@ static bool pmu_is_uncore(int dirfd, const char *name)
> {
> int fd;
>
> - if (perf_pmu__hybrid_mounted(name))
> - return false;
> -
> fd = perf_pmu__pathname_fd(dirfd, name, "cpumask", O_PATH);
> if (fd < 0)
> return false;
> @@ -900,6 +897,16 @@ static int pmu_max_precise(int dirfd, struct perf_pmu *pmu)
> return max_precise;
> }
>
> +/**
> + * perf_pmu__skip_empty_cpus() - should pmu_lookup skip the named PMU if the
> + * cpus or cpumask file isn't present?
> + * @name: Name of PMU.
> + */
> +static bool perf_pmu__skip_empty_cpus(const char *name)
> +{
> + return !strcmp(name, "cpu_core") || !strcmp(name, "cpu_atom");

Can we use the below to replace?
return !strncmp(name, "cpu_", 4);

Otherwise, anytime a new core PMU name is introduced, I have to patch
the function.

Thanks,
Kan

> +}
> +
> static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
> {
> struct perf_pmu *pmu;
> @@ -907,15 +914,8 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
> LIST_HEAD(aliases);
> __u32 type;
> char *name = pmu_find_real_name(lookup_name);
> - bool is_hybrid = perf_pmu__hybrid_mounted(name);
> char *alias_name;
>
> - /*
> - * Check pmu name for hybrid and the pmu may be invalid in sysfs
> - */
> - if (!strncmp(name, "cpu_", 4) && !is_hybrid)
> - return NULL;
> -
> /*
> * The pmu data we store & need consists of the pmu
> * type value and format definitions. Load both right
> @@ -935,8 +935,10 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
> return NULL;
>
> pmu->cpus = pmu_cpumask(dirfd, name);
> - pmu->name = strdup(name);
> + if (!pmu->cpus && perf_pmu__skip_empty_cpus(name))
> + goto err;
>
> + pmu->name = strdup(name);
> if (!pmu->name)
> goto err;
>
> @@ -967,7 +969,7 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
> list_splice(&aliases, &pmu->aliases);
> list_add_tail(&pmu->list, &pmus);
>
> - if (is_hybrid)
> + if (!strcmp(name, "cpu_core") || !strcmp(name, "cpu_atom"))
> list_add_tail(&pmu->hybrid_list, &perf_pmu__hybrid_pmus);
> else
> INIT_LIST_HEAD(&pmu->hybrid_list);