Re: [PATCH 2/2] perf: Replace MAX_NR_CPUS with dynamic alternatives

[Arnaldo Carvalho de Melo]

Em Tue, Aug 13, 2019 at 04:06:13PM -0500, Kyle Meyer escreveu:
> Both cpu__max_cpu and env.nr_cpus_online are dynamic alternatives for
> MAX_NR_CPUS, a macro currently used throughout perf. The function cpu__max_cpu
> returns the possible number of CPUS as defined in the sysfs, whereas
> env.nr_cpus_online is the number of CPUs that were online during the recording
> session. MAX_NR_CPUS is still used by DECLARE_BITMAP at compile time, however,
> it's replaced elsewhere.
> 
> This patch was tested using "perf record -a -g" on both an eight socket 288 CPU
> system and a single socket 36 CPU system. Each system was then rebooted single
> socket and eight socket before "perf report" was used to read the perf.data out
> file. "perf report --header" was used to confirm that each perf.data file had
> information on the correct number of CPUs.

Can you please further break this into multiple patches,  one for the
svg code, another for the header and so on.

Thanks,

- Arnaldo
 
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Russ Anderson <russ.anderson@xxxxxxx>
> Signed-off-by: Kyle Meyer <kyle.meyer@xxxxxxx>
> ---
>  tools/perf/util/header.c    |  6 +++---
>  tools/perf/util/machine.c   | 11 ++++++-----
>  tools/perf/util/session.c   |  6 +++---
>  tools/perf/util/stat.c      |  4 ++--
>  tools/perf/util/svghelper.c | 31 +++++++++++++++----------------
>  5 files changed, 29 insertions(+), 29 deletions(-)
> 
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index b04c2b6b28b3..cf8ce839cb47 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -1121,16 +1121,16 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
>  	return 0;
>  }
>  
> -#define MAX_CACHES (MAX_NR_CPUS * 4)
> +#define MAX_CACHE_LVL 4
>  
>  static int write_cache(struct feat_fd *ff,
>  		       struct evlist *evlist __maybe_unused)
>  {
> -	struct cpu_cache_level caches[MAX_CACHES];
> +	struct cpu_cache_level caches[(cpu__max_cpu() * MAX_CACHE_LVL)];
>  	u32 cnt = 0, i, version = 1;
>  	int ret;
>  
> -	ret = build_caches(caches, MAX_CACHES, &cnt);
> +	ret = build_caches(caches, (cpu__max_cpu() * MAX_CACHE_LVL), &cnt);
>  	if (ret)
>  		goto out;
>  
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 5734460fc89e..cf5f4b4eeea0 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2616,7 +2616,8 @@ int __machine__synthesize_threads(struct machine *machine, struct perf_tool *too
>  
>  pid_t machine__get_current_tid(struct machine *machine, int cpu)
>  {
> -	if (cpu < 0 || cpu >= MAX_NR_CPUS || !machine->current_tid)
> +	int nr_cpus_online = machine->env->nr_cpus_online;
> +	if (cpu < 0 || cpu >= nr_cpus_online || !machine->current_tid)
>  		return -1;
>  
>  	return machine->current_tid[cpu];
> @@ -2626,6 +2627,7 @@ int machine__set_current_tid(struct machine *machine, int cpu, pid_t pid,
>  			     pid_t tid)
>  {
>  	struct thread *thread;
> +	int nr_cpus_online = machine->env->nr_cpus_online;
>  
>  	if (cpu < 0)
>  		return -EINVAL;
> @@ -2633,16 +2635,15 @@ int machine__set_current_tid(struct machine *machine, int cpu, pid_t pid,
>  	if (!machine->current_tid) {
>  		int i;
>  
> -		machine->current_tid = calloc(MAX_NR_CPUS, sizeof(pid_t));
> +		machine->current_tid = calloc(nr_cpus_online, sizeof(pid_t));
>  		if (!machine->current_tid)
>  			return -ENOMEM;
> -		for (i = 0; i < MAX_NR_CPUS; i++)
> +		for (i = 0; i < nr_cpus_online; i++)
>  			machine->current_tid[i] = -1;
>  	}
>  
> -	if (cpu >= MAX_NR_CPUS) {
> +	if (cpu >= nr_cpus_online) {
>  		pr_err("Requested CPU %d too large. ", cpu);
> -		pr_err("Consider raising MAX_NR_CPUS\n");
>  		return -EINVAL;
>  	}
>  
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 11e6093c941b..a9d244a94e24 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -2275,6 +2275,7 @@ int perf_session__cpu_bitmap(struct perf_session *session,
>  {
>  	int i, err = -1;
>  	struct perf_cpu_map *map;
> +	int nr_cpus_online = session->header.env.nr_cpus_online;
>  
>  	for (i = 0; i < PERF_TYPE_MAX; ++i) {
>  		struct evsel *evsel;
> @@ -2299,9 +2300,8 @@ int perf_session__cpu_bitmap(struct perf_session *session,
>  	for (i = 0; i < map->nr; i++) {
>  		int cpu = map->map[i];
>  
> -		if (cpu >= MAX_NR_CPUS) {
> -			pr_err("Requested CPU %d too large. "
> -			       "Consider raising MAX_NR_CPUS\n", cpu);
> +		if (cpu >= nr_cpus_online) {
> +			pr_err("Requested CPU %d too large\n", cpu);
>  			goto out_delete_map;
>  		}
>  
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index e4e4e3bf8b2b..199008ce936d 100644
> --- a/tools/perf/util/stat.c
> +++ b/tools/perf/util/stat.c
> @@ -208,7 +208,7 @@ void perf_evlist__reset_stats(struct evlist *evlist)
>  static void zero_per_pkg(struct evsel *counter)
>  {
>  	if (counter->per_pkg_mask)
> -		memset(counter->per_pkg_mask, 0, MAX_NR_CPUS);
> +		memset(counter->per_pkg_mask, 0, cpu__max_cpu());
>  }
>  
>  static int check_per_pkg(struct evsel *counter,
> @@ -227,7 +227,7 @@ static int check_per_pkg(struct evsel *counter,
>  		return 0;
>  
>  	if (!mask) {
> -		mask = zalloc(MAX_NR_CPUS);
> +		mask = zalloc(cpu__max_cpu());
>  		if (!mask)
>  			return -ENOMEM;
>  
> diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
> index 1beeb7291361..6e8433e97f21 100644
> --- a/tools/perf/util/svghelper.c
> +++ b/tools/perf/util/svghelper.c
> @@ -695,7 +695,8 @@ struct topology {
>  	int sib_thr_nr;
>  };
>  
> -static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos)
> +static void scan_thread_topology(int *map, struct topology *t, int cpu,
> +int *pos, int max_cpus)
>  {
>  	int i;
>  	int thr;
> @@ -704,28 +705,24 @@ static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos
>  		if (!test_bit(cpu, cpumask_bits(&t->sib_thr[i])))
>  			continue;
>  
> -		for_each_set_bit(thr,
> -				 cpumask_bits(&t->sib_thr[i]),
> -				 MAX_NR_CPUS)
> +		for_each_set_bit(thr, cpumask_bits(&t->sib_thr[i]), max_cpus)
>  			if (map[thr] == -1)
>  				map[thr] = (*pos)++;
>  	}
>  }
>  
> -static void scan_core_topology(int *map, struct topology *t)
> +static void scan_core_topology(int *map, struct topology *t, int max_cpus)
>  {
>  	int pos = 0;
>  	int i;
>  	int cpu;
>  
>  	for (i = 0; i < t->sib_core_nr; i++)
> -		for_each_set_bit(cpu,
> -				 cpumask_bits(&t->sib_core[i]),
> -				 MAX_NR_CPUS)
> -			scan_thread_topology(map, t, cpu, &pos);
> +		for_each_set_bit(cpu, cpumask_bits(&t->sib_core[i]), max_cpus)
> +			scan_thread_topology(map, t, cpu, &pos, max_cpus);
>  }
>  
> -static int str_to_bitmap(char *s, cpumask_t *b)
> +static int str_to_bitmap(char *s, cpumask_t *b, int max_cpus)
>  {
>  	int i;
>  	int ret = 0;
> @@ -738,7 +735,7 @@ static int str_to_bitmap(char *s, cpumask_t *b)
>  
>  	for (i = 0; i < m->nr; i++) {
>  		c = m->map[i];
> -		if (c >= MAX_NR_CPUS) {
> +		if (c >= max_cpus) {
>  			ret = -1;
>  			break;
>  		}
> @@ -767,7 +764,8 @@ int svg_build_topology_map(struct perf_env *env)
>  	}
>  
>  	for (i = 0; i < env->nr_sibling_cores; i++) {
> -		if (str_to_bitmap(env->sibling_cores, &t.sib_core[i])) {
> +		if (str_to_bitmap(env->sibling_cores, &t.sib_core[i],
> +			env->nr_cpus_online)) {
>  			fprintf(stderr, "topology: can't parse siblings map\n");
>  			goto exit;
>  		}
> @@ -776,7 +774,8 @@ int svg_build_topology_map(struct perf_env *env)
>  	}
>  
>  	for (i = 0; i < env->nr_sibling_threads; i++) {
> -		if (str_to_bitmap(env->sibling_threads, &t.sib_thr[i])) {
> +		if (str_to_bitmap(env->sibling_threads, &t.sib_thr[i],
> +			env->nr_cpus_online)) {
>  			fprintf(stderr, "topology: can't parse siblings map\n");
>  			goto exit;
>  		}
> @@ -784,16 +783,16 @@ int svg_build_topology_map(struct perf_env *env)
>  		env->sibling_threads += strlen(env->sibling_threads) + 1;
>  	}
>  
> -	topology_map = malloc(sizeof(int) * MAX_NR_CPUS);
> +	topology_map = malloc(sizeof(int) * env->nr_cpus_online);
>  	if (!topology_map) {
>  		fprintf(stderr, "topology: no memory\n");
>  		goto exit;
>  	}
>  
> -	for (i = 0; i < MAX_NR_CPUS; i++)
> +	for (i = 0; i < env->nr_cpus_online; i++)
>  		topology_map[i] = -1;
>  
> -	scan_core_topology(topology_map, &t);
> +	scan_core_topology(topology_map, &t, env->nr_cpus_online);
>  
>  	return 0;
>  
> -- 
> 2.12.3

-- 

- Arnaldo