[PATCH] perf tools: Replace MAX_NR_CPUS with nr_cpus_onln

[PATCH] perf tools: Replace MAX_NR_CPUS with nr_cpus_onln

[Kyle Meyer]

The variables nr_cpus_onln and max_caches are dynamic alternatives for
MAX_NR_CPUS and MAX_CACHES as they are initialized at runtime. MAX_NR_CPUS
is still used by DECLARE_BITMAP() at compile time, however, nr_cpus_onln
replaces it elsewhere throughout perf.

This patch was tested using "perf record -a -g" on both an eight socket
(288 CPUs) system and a single socket (36 CPUs) system. Each system was then
rebooted single socket (36 CPUs) / eight socket (288 CPUs) and "perf
report" used to read the perf.data file. "perf report --header" was used to
confirm that each perf.data had information on 288 CPUs / 36 CPUs.

This patch is meant to be built against perf tools: Increase MAX_NR_CPUS and
MAX_CACHES (commit 9f94c7f947e919c343b30f080285af53d0fa9902).

Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
Cc: Russ Anderson <russ.anderson@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
 tools/perf/perf.c           | 10 ++++++++++
 tools/perf/perf.h           |  1 +
 tools/perf/util/cpumap.c    |  6 +++---
 tools/perf/util/header.c    |  5 +++--
 tools/perf/util/machine.c   | 11 +++++------
 tools/perf/util/stat.c      |  4 ++--
 tools/perf/util/svghelper.c | 10 +++++-----
 7 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 97e2628ea5dd..0d0162fb4e24 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -428,6 +428,16 @@ int main(int argc, const char **argv)
 	const char *cmd;
 	char sbuf[STRERR_BUFSIZE];
 
+	nr_cpus_onln = sysconf(_SC_NPROCESSORS_ONLN);
+	if (nr_cpus_onln < 0) {
+		fprintf(stderr, "Cannot determine the number of CPUs currently online.\n");
+		goto out;
+	} 
+	if (nr_cpus_onln > MAX_NR_CPUS) {
+		fprintf(stderr, "The number of CPUs currently online is too large, consider raising MAX_NR_CPUS.\n");
+		nr_cpus_onln = MAX_NR_CPUS;
+	}
+
 	/* libsubcmd init */
 	exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
 	pager_init(PERF_PAGER_ENVIRONMENT);
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 74d0124d38f3..603391cac85b 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -29,6 +29,7 @@ static inline unsigned long long rdclock(void)
 #define MAX_NR_CPUS			2048
 #endif
 
+int nr_cpus_onln;
 extern const char *input_name;
 extern bool perf_host, perf_guest;
 extern const char perf_version_string[];
diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 3acfbe34ebaf..f634c56b1388 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -72,7 +72,7 @@ struct cpu_map *cpu_map__read(FILE *file)
 			int new_max = nr_cpus + cpu - prev - 1;
 
 			if (new_max >= max_entries) {
-				max_entries = new_max + MAX_NR_CPUS / 2;
+				max_entries = new_max + nr_cpus_onln / 2;
 				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 				if (tmp == NULL)
 					goto out_free_tmp;
@@ -83,7 +83,7 @@ struct cpu_map *cpu_map__read(FILE *file)
 				tmp_cpus[nr_cpus++] = prev;
 		}
 		if (nr_cpus == max_entries) {
-			max_entries += MAX_NR_CPUS;
+			max_entries += nr_cpus_onln;
 			tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 			if (tmp == NULL)
 				goto out_free_tmp;
@@ -170,7 +170,7 @@ struct cpu_map *cpu_map__new(const char *cpu_list)
 					goto invalid;
 
 			if (nr_cpus == max_entries) {
-				max_entries += MAX_NR_CPUS;
+				max_entries += nr_cpus_onln;
 				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 				if (tmp == NULL)
 					goto invalid;
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index c24db7f4909c..030c0a8f6664 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1125,11 +1125,12 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
 static int write_cache(struct feat_fd *ff,
 		       struct perf_evlist *evlist __maybe_unused)
 {
-	struct cpu_cache_level caches[MAX_CACHES];
+	u32 max_caches = (nr_cpus_onln * 4);
+	struct cpu_cache_level caches[max_caches];
 	u32 cnt = 0, i, version = 1;
 	int ret;
 
-	ret = build_caches(caches, MAX_CACHES, &cnt);
+	ret = build_caches(caches, max_caches, &cnt);
 	if (ret)
 		goto out;
 
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index cf826eca3aaf..92720240676d 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2615,7 +2615,7 @@ 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)
+	if (cpu < 0 || cpu >= nr_cpus_onln || !machine->current_tid)
 		return -1;
 
 	return machine->current_tid[cpu];
@@ -2632,16 +2632,15 @@ 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_onln, sizeof(pid_t));
 		if (!machine->current_tid)
 			return -ENOMEM;
-		for (i = 0; i < MAX_NR_CPUS; i++)
+		for (i = 0; i < nr_cpus_onln; i++)
 			machine->current_tid[i] = -1;
 	}
 
-	if (cpu >= MAX_NR_CPUS) {
-		pr_err("Requested CPU %d too large. ", cpu);
-		pr_err("Consider raising MAX_NR_CPUS\n");
+	if (cpu >= nr_cpus_onln) {
+		pr_err("Requested CPU %d too large, there are %d CPUs currently online.\n", cpu, nr_cpus_onln);
 		return -EINVAL;
 	}
 
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index db8a6cf336be..f87bdc140a4b 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -208,7 +208,7 @@ void perf_evlist__reset_stats(struct perf_evlist *evlist)
 static void zero_per_pkg(struct perf_evsel *counter)
 {
 	if (counter->per_pkg_mask)
-		memset(counter->per_pkg_mask, 0, MAX_NR_CPUS);
+		memset(counter->per_pkg_mask, 0, nr_cpus_onln);
 }
 
 static int check_per_pkg(struct perf_evsel *counter,
@@ -227,7 +227,7 @@ static int check_per_pkg(struct perf_evsel *counter,
 		return 0;
 
 	if (!mask) {
-		mask = zalloc(MAX_NR_CPUS);
+		mask = zalloc(nr_cpus_onln);
 		if (!mask)
 			return -ENOMEM;
 
diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
index 76cc54000483..4c38f70520c5 100644
--- a/tools/perf/util/svghelper.c
+++ b/tools/perf/util/svghelper.c
@@ -705,7 +705,7 @@ static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos
 
 		for_each_set_bit(thr,
 				 cpumask_bits(&t->sib_thr[i]),
-				 MAX_NR_CPUS)
+				 nr_cpus_onln)
 			if (map[thr] == -1)
 				map[thr] = (*pos)++;
 	}
@@ -720,7 +720,7 @@ static void scan_core_topology(int *map, struct topology *t)
 	for (i = 0; i < t->sib_core_nr; i++)
 		for_each_set_bit(cpu,
 				 cpumask_bits(&t->sib_core[i]),
-				 MAX_NR_CPUS)
+				 nr_cpus_onln)
 			scan_thread_topology(map, t, cpu, &pos);
 }
 
@@ -737,7 +737,7 @@ 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 >= nr_cpus_onln) {
 			ret = -1;
 			break;
 		}
@@ -784,13 +784,13 @@ int svg_build_topology_map(char *sib_core, int sib_core_nr,
 		sib_thr += strlen(sib_thr) + 1;
 	}
 
-	topology_map = malloc(sizeof(int) * MAX_NR_CPUS);
+	topology_map = malloc(sizeof(int) * nr_cpus_onln);
 	if (!topology_map) {
 		fprintf(stderr, "topology: no memory\n");
 		goto exit;
 	}
 
-	for (i = 0; i < MAX_NR_CPUS; i++)
+	for (i = 0; i < nr_cpus_onln; i++)
 		topology_map[i] = -1;
 
 	scan_core_topology(topology_map, &t);
-- 
2.12.3

Re: [PATCH] perf tools: Replace MAX_NR_CPUS with nr_cpus_onln

[Jiri Olsa]

On Fri, Jul 26, 2019 at 02:51:39PM -0500, Kyle Meyer wrote:
> The variables nr_cpus_onln and max_caches are dynamic alternatives for
> MAX_NR_CPUS and MAX_CACHES as they are initialized at runtime. MAX_NR_CPUS
> is still used by DECLARE_BITMAP() at compile time, however, nr_cpus_onln
> replaces it elsewhere throughout perf.
> 
> This patch was tested using "perf record -a -g" on both an eight socket
> (288 CPUs) system and a single socket (36 CPUs) system. Each system was then
> rebooted single socket (36 CPUs) / eight socket (288 CPUs) and "perf
> report" used to read the perf.data file. "perf report --header" was used to
> confirm that each perf.data had information on 288 CPUs / 36 CPUs.
> 
> This patch is meant to be built against perf tools: Increase MAX_NR_CPUS and
> MAX_CACHES (commit 9f94c7f947e919c343b30f080285af53d0fa9902).

hi,
could you please rebase to latest Arnaldo's perf/core,
the cpumap.c got changed recently and I can't apply
your patch anymore:

	patching file perf.c
	patching file perf.h
	patching file util/cpumap.c
	Hunk #1 FAILED at 72.
	Hunk #2 FAILED at 83.
	Hunk #3 FAILED at 170.
	3 out of 3 hunks FAILED -- saving rejects to file util/cpumap.c.rej
	patching file util/header.c
	Hunk #1 succeeded at 1126 with fuzz 2 (offset 1 line).
	patching file util/machine.c
	patching file util/stat.c
	Hunk #1 succeeded at 208 with fuzz 1.
	patching file util/svghelper.c
	Hunk #1 succeeded at 706 (offset 1 line).
	Hunk #2 succeeded at 721 (offset 1 line).
	Hunk #3 succeeded at 738 (offset 1 line).
	Hunk #4 succeeded at 785 (offset 1 line).

thanks,
jirka

> 
> Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
> Cc: Russ Anderson <russ.anderson@hpe.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: linux-kernel@vger.kernel.org
> ---
>  tools/perf/perf.c           | 10 ++++++++++
>  tools/perf/perf.h           |  1 +
>  tools/perf/util/cpumap.c    |  6 +++---
>  tools/perf/util/header.c    |  5 +++--
>  tools/perf/util/machine.c   | 11 +++++------
>  tools/perf/util/stat.c      |  4 ++--
>  tools/perf/util/svghelper.c | 10 +++++-----
>  7 files changed, 29 insertions(+), 18 deletions(-)
> 
> diff --git a/tools/perf/perf.c b/tools/perf/perf.c
> index 97e2628ea5dd..0d0162fb4e24 100644
> --- a/tools/perf/perf.c
> +++ b/tools/perf/perf.c
> @@ -428,6 +428,16 @@ int main(int argc, const char **argv)
>  	const char *cmd;
>  	char sbuf[STRERR_BUFSIZE];
>  
> +	nr_cpus_onln = sysconf(_SC_NPROCESSORS_ONLN);
> +	if (nr_cpus_onln < 0) {
> +		fprintf(stderr, "Cannot determine the number of CPUs currently online.\n");
> +		goto out;
> +	} 
> +	if (nr_cpus_onln > MAX_NR_CPUS) {
> +		fprintf(stderr, "The number of CPUs currently online is too large, consider raising MAX_NR_CPUS.\n");
> +		nr_cpus_onln = MAX_NR_CPUS;
> +	}
> +
>  	/* libsubcmd init */
>  	exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
>  	pager_init(PERF_PAGER_ENVIRONMENT);
> diff --git a/tools/perf/perf.h b/tools/perf/perf.h
> index 74d0124d38f3..603391cac85b 100644
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -29,6 +29,7 @@ static inline unsigned long long rdclock(void)
>  #define MAX_NR_CPUS			2048
>  #endif
>  
> +int nr_cpus_onln;
>  extern const char *input_name;
>  extern bool perf_host, perf_guest;
>  extern const char perf_version_string[];
> diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
> index 3acfbe34ebaf..f634c56b1388 100644
> --- a/tools/perf/util/cpumap.c
> +++ b/tools/perf/util/cpumap.c
> @@ -72,7 +72,7 @@ struct cpu_map *cpu_map__read(FILE *file)
>  			int new_max = nr_cpus + cpu - prev - 1;
>  
>  			if (new_max >= max_entries) {
> -				max_entries = new_max + MAX_NR_CPUS / 2;
> +				max_entries = new_max + nr_cpus_onln / 2;
>  				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
>  				if (tmp == NULL)
>  					goto out_free_tmp;
> @@ -83,7 +83,7 @@ struct cpu_map *cpu_map__read(FILE *file)
>  				tmp_cpus[nr_cpus++] = prev;
>  		}
>  		if (nr_cpus == max_entries) {
> -			max_entries += MAX_NR_CPUS;
> +			max_entries += nr_cpus_onln;
>  			tmp = realloc(tmp_cpus, max_entries * sizeof(int));
>  			if (tmp == NULL)
>  				goto out_free_tmp;
> @@ -170,7 +170,7 @@ struct cpu_map *cpu_map__new(const char *cpu_list)
>  					goto invalid;
>  
>  			if (nr_cpus == max_entries) {
> -				max_entries += MAX_NR_CPUS;
> +				max_entries += nr_cpus_onln;
>  				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
>  				if (tmp == NULL)
>  					goto invalid;
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index c24db7f4909c..030c0a8f6664 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -1125,11 +1125,12 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
>  static int write_cache(struct feat_fd *ff,
>  		       struct perf_evlist *evlist __maybe_unused)
>  {
> -	struct cpu_cache_level caches[MAX_CACHES];
> +	u32 max_caches = (nr_cpus_onln * 4);
> +	struct cpu_cache_level caches[max_caches];
>  	u32 cnt = 0, i, version = 1;
>  	int ret;
>  
> -	ret = build_caches(caches, MAX_CACHES, &cnt);
> +	ret = build_caches(caches, max_caches, &cnt);
>  	if (ret)
>  		goto out;
>  
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index cf826eca3aaf..92720240676d 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2615,7 +2615,7 @@ 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)
> +	if (cpu < 0 || cpu >= nr_cpus_onln || !machine->current_tid)
>  		return -1;
>  
>  	return machine->current_tid[cpu];
> @@ -2632,16 +2632,15 @@ 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_onln, sizeof(pid_t));
>  		if (!machine->current_tid)
>  			return -ENOMEM;
> -		for (i = 0; i < MAX_NR_CPUS; i++)
> +		for (i = 0; i < nr_cpus_onln; i++)
>  			machine->current_tid[i] = -1;
>  	}
>  
> -	if (cpu >= MAX_NR_CPUS) {
> -		pr_err("Requested CPU %d too large. ", cpu);
> -		pr_err("Consider raising MAX_NR_CPUS\n");
> +	if (cpu >= nr_cpus_onln) {
> +		pr_err("Requested CPU %d too large, there are %d CPUs currently online.\n", cpu, nr_cpus_onln);
>  		return -EINVAL;
>  	}
>  
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index db8a6cf336be..f87bdc140a4b 100644
> --- a/tools/perf/util/stat.c
> +++ b/tools/perf/util/stat.c
> @@ -208,7 +208,7 @@ void perf_evlist__reset_stats(struct perf_evlist *evlist)
>  static void zero_per_pkg(struct perf_evsel *counter)
>  {
>  	if (counter->per_pkg_mask)
> -		memset(counter->per_pkg_mask, 0, MAX_NR_CPUS);
> +		memset(counter->per_pkg_mask, 0, nr_cpus_onln);
>  }
>  
>  static int check_per_pkg(struct perf_evsel *counter,
> @@ -227,7 +227,7 @@ static int check_per_pkg(struct perf_evsel *counter,
>  		return 0;
>  
>  	if (!mask) {
> -		mask = zalloc(MAX_NR_CPUS);
> +		mask = zalloc(nr_cpus_onln);
>  		if (!mask)
>  			return -ENOMEM;
>  
> diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
> index 76cc54000483..4c38f70520c5 100644
> --- a/tools/perf/util/svghelper.c
> +++ b/tools/perf/util/svghelper.c
> @@ -705,7 +705,7 @@ static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos
>  
>  		for_each_set_bit(thr,
>  				 cpumask_bits(&t->sib_thr[i]),
> -				 MAX_NR_CPUS)
> +				 nr_cpus_onln)
>  			if (map[thr] == -1)
>  				map[thr] = (*pos)++;
>  	}
> @@ -720,7 +720,7 @@ static void scan_core_topology(int *map, struct topology *t)
>  	for (i = 0; i < t->sib_core_nr; i++)
>  		for_each_set_bit(cpu,
>  				 cpumask_bits(&t->sib_core[i]),
> -				 MAX_NR_CPUS)
> +				 nr_cpus_onln)
>  			scan_thread_topology(map, t, cpu, &pos);
>  }
>  
> @@ -737,7 +737,7 @@ 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 >= nr_cpus_onln) {
>  			ret = -1;
>  			break;
>  		}
> @@ -784,13 +784,13 @@ int svg_build_topology_map(char *sib_core, int sib_core_nr,
>  		sib_thr += strlen(sib_thr) + 1;
>  	}
>  
> -	topology_map = malloc(sizeof(int) * MAX_NR_CPUS);
> +	topology_map = malloc(sizeof(int) * nr_cpus_onln);
>  	if (!topology_map) {
>  		fprintf(stderr, "topology: no memory\n");
>  		goto exit;
>  	}
>  
> -	for (i = 0; i < MAX_NR_CPUS; i++)
> +	for (i = 0; i < nr_cpus_onln; i++)
>  		topology_map[i] = -1;
>  
>  	scan_core_topology(topology_map, &t);
> -- 
> 2.12.3
> 

[PATCH] perf tools: Replace MAX_NR_CPUS with nr_cpus_onln

[Kyle Meyer]

The variables nr_cpus_onln and max_caches are dynamic alternatives for
MAX_NR_CPUS and MAX_CACHES as they are initialized at runtime. MAX_NR_CPUS
is still used by DECLARE_BITMAP() at compile time, however, nr_cpus_onln
replaces it elsewhere throughout perf.

This patch was tested using "perf record -a -g" on both an eight socket
(288 CPUs) system and a single socket (36 CPUs) system. Each system was then
rebooted single socket (36 CPUs) / eight socket (288 CPUs) and "perf
report" used to read the perf.data file. "perf report --header" was used to
confirm that each perf.data had information on 288 CPUs / 36 CPUs.

Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
Cc: Russ Anderson <russ.anderson@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
 tools/perf/lib/cpumap.c     |  6 +++---
 tools/perf/perf.c           | 10 ++++++++++
 tools/perf/perf.h           |  1 +
 tools/perf/util/header.c    |  7 +++----
 tools/perf/util/machine.c   | 11 +++++------
 tools/perf/util/stat.c      |  4 ++--
 tools/perf/util/svghelper.c | 10 +++++-----
 7 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/tools/perf/lib/cpumap.c b/tools/perf/lib/cpumap.c
index 1ddb69e796e5..327a37c68e73 100644
--- a/tools/perf/lib/cpumap.c
+++ b/tools/perf/lib/cpumap.c
@@ -101,7 +101,7 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
 			int new_max = nr_cpus + cpu - prev - 1;
 
 			if (new_max >= max_entries) {
-				max_entries = new_max + MAX_NR_CPUS / 2;
+				max_entries = new_max + nr_cpus_onln / 2;
 				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 				if (tmp == NULL)
 					goto out_free_tmp;
@@ -112,7 +112,7 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
 				tmp_cpus[nr_cpus++] = prev;
 		}
 		if (nr_cpus == max_entries) {
-			max_entries += MAX_NR_CPUS;
+			max_entries += nr_cpus_onln;
 			tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 			if (tmp == NULL)
 				goto out_free_tmp;
@@ -199,7 +199,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
 					goto invalid;
 
 			if (nr_cpus == max_entries) {
-				max_entries += MAX_NR_CPUS;
+				max_entries += nr_cpus_onln;
 				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
 				if (tmp == NULL)
 					goto invalid;
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 97e2628ea5dd..658bf8501bb0 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -428,6 +428,16 @@ int main(int argc, const char **argv)
 	const char *cmd;
 	char sbuf[STRERR_BUFSIZE];
 
+	nr_cpus_onln = sysconf(_SC_NPROCESSORS_ONLN);
+	if (nr_cpus_onln < 0) {
+		fprintf(stderr, "Cannot determine the number of CPUs currently online.\n");
+		goto out;
+	}
+	if (nr_cpus_onln > MAX_NR_CPUS) {
+		fprintf(stderr, "The number of CPUs currently online is too large, consider raising MAX_NR_CPUS.\n");
+		nr_cpus_onln = MAX_NR_CPUS;
+	}
+	
 	/* libsubcmd init */
 	exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
 	pager_init(PERF_PAGER_ENVIRONMENT);
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 74d0124d38f3..603391cac85b 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -29,6 +29,7 @@ static inline unsigned long long rdclock(void)
 #define MAX_NR_CPUS			2048
 #endif
 
+int nr_cpus_onln;
 extern const char *input_name;
 extern bool perf_host, perf_guest;
 extern const char perf_version_string[];
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index b04c2b6b28b3..7983d268eec1 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1121,16 +1121,15 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
 	return 0;
 }
 
-#define MAX_CACHES (MAX_NR_CPUS * 4)
-
 static int write_cache(struct feat_fd *ff,
 		       struct evlist *evlist __maybe_unused)
 {
-	struct cpu_cache_level caches[MAX_CACHES];
+	u32 max_caches = (nr_cpus_online * 4);
+	struct cpu_cache_level caches[max_caches]
 	u32 cnt = 0, i, version = 1;
 	int ret;
 
-	ret = build_caches(caches, MAX_CACHES, &cnt);
+	ret = build_caches(caches, max_caches, &cnt);
 	if (ret)
 		goto out;
 
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index f6ee7fbad3e4..3ad77d5e8aab 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2615,7 +2615,7 @@ 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)
+	if (cpu < 0 || cpu >= nr_cpus_onln || !machine->current_tid)
 		return -1;
 
 	return machine->current_tid[cpu];
@@ -2632,16 +2632,15 @@ 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_onln, sizeof(pid_t));
 		if (!machine->current_tid)
 			return -ENOMEM;
-		for (i = 0; i < MAX_NR_CPUS; i++)
+		for (i = 0; i < nr_cpus_onln; i++)
 			machine->current_tid[i] = -1;
 	}
 
-	if (cpu >= MAX_NR_CPUS) {
-		pr_err("Requested CPU %d too large. ", cpu);
-		pr_err("Consider raising MAX_NR_CPUS\n");
+	if (cpu >= nr_cpus_onln) {
+		pr_err("Requested CPU %d too large, there are %d CPUs currently online.\n", cpu, nr_cpus_onln);
 		return -EINVAL;
 	}
 
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index e4e4e3bf8b2b..42dddbd2f23c 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, nr_cpus_onln);
 }
 
 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(nr_cpus_onln);
 		if (!mask)
 			return -ENOMEM;
 
diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
index ae6a534a7a80..0404bd87812a 100644
--- a/tools/perf/util/svghelper.c
+++ b/tools/perf/util/svghelper.c
@@ -706,7 +706,7 @@ static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos
 
 		for_each_set_bit(thr,
 				 cpumask_bits(&t->sib_thr[i]),
-				 MAX_NR_CPUS)
+				 nr_cpus_onln)
 			if (map[thr] == -1)
 				map[thr] = (*pos)++;
 	}
@@ -721,7 +721,7 @@ static void scan_core_topology(int *map, struct topology *t)
 	for (i = 0; i < t->sib_core_nr; i++)
 		for_each_set_bit(cpu,
 				 cpumask_bits(&t->sib_core[i]),
-				 MAX_NR_CPUS)
+				 nr_cpus_onln)
 			scan_thread_topology(map, t, cpu, &pos);
 }
 
@@ -738,7 +738,7 @@ 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 >= nr_cpus_onln) {
 			ret = -1;
 			break;
 		}
@@ -785,13 +785,13 @@ int svg_build_topology_map(char *sib_core, int sib_core_nr,
 		sib_thr += strlen(sib_thr) + 1;
 	}
 
-	topology_map = malloc(sizeof(int) * MAX_NR_CPUS);
+	topology_map = malloc(sizeof(int) * nr_cpus_onln);
 	if (!topology_map) {
 		fprintf(stderr, "topology: no memory\n");
 		goto exit;
 	}
 
-	for (i = 0; i < MAX_NR_CPUS; i++)
+	for (i = 0; i < nr_cpus_onln; i++)
 		topology_map[i] = -1;
 
 	scan_core_topology(topology_map, &t);
-- 
2.12.3

Re: [PATCH] perf tools: Replace MAX_NR_CPUS with nr_cpus_onln

[Jiri Olsa]

On Fri, Aug 02, 2019 at 03:16:42PM -0500, Kyle Meyer wrote:
> The variables nr_cpus_onln and max_caches are dynamic alternatives for
> MAX_NR_CPUS and MAX_CACHES as they are initialized at runtime. MAX_NR_CPUS
> is still used by DECLARE_BITMAP() at compile time, however, nr_cpus_onln
> replaces it elsewhere throughout perf.
> 
> This patch was tested using "perf record -a -g" on both an eight socket
> (288 CPUs) system and a single socket (36 CPUs) system. Each system was then
> rebooted single socket (36 CPUs) / eight socket (288 CPUs) and "perf
> report" used to read the perf.data file. "perf report --header" was used to
> confirm that each perf.data had information on 288 CPUs / 36 CPUs.
> 
> Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
> Cc: Russ Anderson <russ.anderson@hpe.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: linux-kernel@vger.kernel.org
> ---
>  tools/perf/lib/cpumap.c     |  6 +++---
>  tools/perf/perf.c           | 10 ++++++++++
>  tools/perf/perf.h           |  1 +
>  tools/perf/util/header.c    |  7 +++----
>  tools/perf/util/machine.c   | 11 +++++------
>  tools/perf/util/stat.c      |  4 ++--
>  tools/perf/util/svghelper.c | 10 +++++-----
>  7 files changed, 29 insertions(+), 20 deletions(-)
> 
> diff --git a/tools/perf/lib/cpumap.c b/tools/perf/lib/cpumap.c
> index 1ddb69e796e5..327a37c68e73 100644
> --- a/tools/perf/lib/cpumap.c
> +++ b/tools/perf/lib/cpumap.c
> @@ -101,7 +101,7 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
>  			int new_max = nr_cpus + cpu - prev - 1;
>  
>  			if (new_max >= max_entries) {
> -				max_entries = new_max + MAX_NR_CPUS / 2;
> +				max_entries = new_max + nr_cpus_onln / 2;
>  				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
>  				if (tmp == NULL)
>  					goto out_free_tmp;
> @@ -112,7 +112,7 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
>  				tmp_cpus[nr_cpus++] = prev;
>  		}
>  		if (nr_cpus == max_entries) {
> -			max_entries += MAX_NR_CPUS;
> +			max_entries += nr_cpus_onln;
>  			tmp = realloc(tmp_cpus, max_entries * sizeof(int));
>  			if (tmp == NULL)
>  				goto out_free_tmp;
> @@ -199,7 +199,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  					goto invalid;
>  
>  			if (nr_cpus == max_entries) {
> -				max_entries += MAX_NR_CPUS;
> +				max_entries += nr_cpus_onln;
>  				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
>  				if (tmp == NULL)
>  					goto invalid;

hi,
now we need to take care about the library,
that reminds me to add automaketed compile
test for this:

	[jolsa@krava perf]$ make -C lib
	make: Entering directory '/home/jolsa/kernel/linux-perf/tools/perf/lib'
	  CC       cpumap.o
	cpumap.c: In function ‘perf_cpu_map__read’:
	cpumap.c:104:29: error: ‘nr_cpus_onln’ undeclared (first use in this function)
	  104 |     max_entries = new_max + nr_cpus_onln / 2;
	      |                             ^~~~~~~~~~~~
	cpumap.c:104:29: note: each undeclared identifier is reported only once for each function it appears in
	cpumap.c: In function ‘perf_cpu_map__new’:
	cpumap.c:202:20: error: ‘nr_cpus_onln’ undeclared (first use in this function)
	  202 |     max_entries += nr_cpus_onln;
	      |                    ^~~~~~~~~~~~
	mv: cannot stat './.cpumap.o.tmp': No such file or directory
	make[2]: *** [/home/jolsa/kernel/linux-perf/tools/build/Makefile.build:97: cpumap.o] Error 1
	make[1]: *** [Makefile:92: libperf-in.o] Error 2
	make: *** [Makefile:107: all] Error 2
	make: Leaving directory '/home/jolsa/kernel/linux-perf/tools/perf/lib'


> diff --git a/tools/perf/perf.c b/tools/perf/perf.c
> index 97e2628ea5dd..658bf8501bb0 100644
> --- a/tools/perf/perf.c
> +++ b/tools/perf/perf.c
> @@ -428,6 +428,16 @@ int main(int argc, const char **argv)
>  	const char *cmd;
>  	char sbuf[STRERR_BUFSIZE];
>  
> +	nr_cpus_onln = sysconf(_SC_NPROCESSORS_ONLN);
> +	if (nr_cpus_onln < 0) {
> +		fprintf(stderr, "Cannot determine the number of CPUs currently online.\n");
> +		goto out;
> +	}
> +	if (nr_cpus_onln > MAX_NR_CPUS) {
> +		fprintf(stderr, "The number of CPUs currently online is too large, consider raising MAX_NR_CPUS.\n");
> +		nr_cpus_onln = MAX_NR_CPUS;
> +	}

so how about if cpu is added during the record session,
should we rather use 'possible' cpus, like in cpu__max_cpu?

also we could move cpu__max_cpu we could to libperf
so the library code would still work

> +	
>  	/* libsubcmd init */
>  	exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
>  	pager_init(PERF_PAGER_ENVIRONMENT);
> diff --git a/tools/perf/perf.h b/tools/perf/perf.h
> index 74d0124d38f3..603391cac85b 100644
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -29,6 +29,7 @@ static inline unsigned long long rdclock(void)
>  #define MAX_NR_CPUS			2048
>  #endif
>  
> +int nr_cpus_onln;
>  extern const char *input_name;
>  extern bool perf_host, perf_guest;
>  extern const char perf_version_string[];
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index b04c2b6b28b3..7983d268eec1 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -1121,16 +1121,15 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
>  	return 0;
>  }
>  
> -#define MAX_CACHES (MAX_NR_CPUS * 4)
> -
>  static int write_cache(struct feat_fd *ff,
>  		       struct evlist *evlist __maybe_unused)
>  {
> -	struct cpu_cache_level caches[MAX_CACHES];
> +	u32 max_caches = (nr_cpus_online * 4);
> +	struct cpu_cache_level caches[max_caches]
>  	u32 cnt = 0, i, version = 1;
>  	int ret;
>  
> -	ret = build_caches(caches, MAX_CACHES, &cnt);
> +	ret = build_caches(caches, max_caches, &cnt);
>  	if (ret)
>  		goto out;
>  
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index f6ee7fbad3e4..3ad77d5e8aab 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2615,7 +2615,7 @@ 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)
> +	if (cpu < 0 || cpu >= nr_cpus_onln || !machine->current_tid)
>  		return -1;
>  

as I said earlier the problem here might be that you change
report path, that needs to check on either MAX_NR_CPUS,
(as it currently does) or the number of cpus of the server
where was perf.data recorded.. which is not necessarily
the one you are running report on..

the cpu info is in perf_session::header::env

machine__get_current_tid is used from intel_pt and
perf_session is part of 'struct intel_pt *pt' caller
argument, so it needs to be passed in here

ale the other changes needs to be check in the same way

thanks,
jirka

>  	return machine->current_tid[cpu];
> @@ -2632,16 +2632,15 @@ 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_onln, sizeof(pid_t));
>  		if (!machine->current_tid)
>  			return -ENOMEM;
> -		for (i = 0; i < MAX_NR_CPUS; i++)
> +		for (i = 0; i < nr_cpus_onln; i++)
>  			machine->current_tid[i] = -1;
>  	}
>  
> -	if (cpu >= MAX_NR_CPUS) {
> -		pr_err("Requested CPU %d too large. ", cpu);
> -		pr_err("Consider raising MAX_NR_CPUS\n");
> +	if (cpu >= nr_cpus_onln) {
> +		pr_err("Requested CPU %d too large, there are %d CPUs currently online.\n", cpu, nr_cpus_onln);
>  		return -EINVAL;
>  	}
>  
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index e4e4e3bf8b2b..42dddbd2f23c 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, nr_cpus_onln);
>  }
>  
>  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(nr_cpus_onln);
>  		if (!mask)
>  			return -ENOMEM;
>  
> diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
> index ae6a534a7a80..0404bd87812a 100644
> --- a/tools/perf/util/svghelper.c
> +++ b/tools/perf/util/svghelper.c
> @@ -706,7 +706,7 @@ static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos
>  
>  		for_each_set_bit(thr,
>  				 cpumask_bits(&t->sib_thr[i]),
> -				 MAX_NR_CPUS)
> +				 nr_cpus_onln)
>  			if (map[thr] == -1)
>  				map[thr] = (*pos)++;
>  	}
> @@ -721,7 +721,7 @@ static void scan_core_topology(int *map, struct topology *t)
>  	for (i = 0; i < t->sib_core_nr; i++)
>  		for_each_set_bit(cpu,
>  				 cpumask_bits(&t->sib_core[i]),
> -				 MAX_NR_CPUS)
> +				 nr_cpus_onln)
>  			scan_thread_topology(map, t, cpu, &pos);
>  }
>  
> @@ -738,7 +738,7 @@ 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 >= nr_cpus_onln) {
>  			ret = -1;
>  			break;
>  		}
> @@ -785,13 +785,13 @@ int svg_build_topology_map(char *sib_core, int sib_core_nr,
>  		sib_thr += strlen(sib_thr) + 1;
>  	}
>  
> -	topology_map = malloc(sizeof(int) * MAX_NR_CPUS);
> +	topology_map = malloc(sizeof(int) * nr_cpus_onln);
>  	if (!topology_map) {
>  		fprintf(stderr, "topology: no memory\n");
>  		goto exit;
>  	}
>  
> -	for (i = 0; i < MAX_NR_CPUS; i++)
> +	for (i = 0; i < nr_cpus_onln; i++)
>  		topology_map[i] = -1;
>  
>  	scan_core_topology(topology_map, &t);
> -- 
> 2.12.3
> 

[PATCH] perf tools: Replace MAX_NR_CPUS with nr_cpus_onln

[Kyle Meyer]

The variables nr_cpus_onln and max_caches are dynamic alternatives for
MAX_NR_CPUS and MAX_CACHES as they are initialized at runtime. MAX_NR_CPUS
is still used by DECLARE_BITMAP() at compile time, however, nr_cpus_onln
replaces it elsewhere throughout perf.

This patch was tested using "perf record -a -g" on both an eight socket
(288 CPUs) system and a single socket (36 CPUs) system. Each system was then
rebooted single socket (36 CPUs) / eight socket (288 CPUs) and "perf
report" used to read the perf.data file. "perf report --header" was used to
confirm that each perf.data had information on 288 CPUs / 36 CPUs.

Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
Cc: Russ Anderson <russ.anderson@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
 tools/perf/perf.c           | 10 ++++++++++
 tools/perf/perf.h           |  1 +
 tools/perf/util/header.c    |  7 +++----
 tools/perf/util/machine.c   | 11 +++++------
 tools/perf/util/stat.c      |  4 ++--
 tools/perf/util/svghelper.c | 10 +++++-----
 6 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 97e2628ea5dd..658bf8501bb0 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -428,6 +428,16 @@ int main(int argc, const char **argv)
 	const char *cmd;
 	char sbuf[STRERR_BUFSIZE];
 
+	nr_cpus_onln = sysconf(_SC_NPROCESSORS_ONLN);
+	if (nr_cpus_onln < 0) {
+		fprintf(stderr, "Cannot determine the number of CPUs currently online.\n");
+		goto out;
+	}
+	if (nr_cpus_onln > MAX_NR_CPUS) {
+		fprintf(stderr, "The number of CPUs currently online is too large, consider raising MAX_NR_CPUS.\n");
+		nr_cpus_onln = MAX_NR_CPUS;
+	}
+	
 	/* libsubcmd init */
 	exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
 	pager_init(PERF_PAGER_ENVIRONMENT);
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 74d0124d38f3..603391cac85b 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -29,6 +29,7 @@ static inline unsigned long long rdclock(void)
 #define MAX_NR_CPUS			2048
 #endif
 
+int nr_cpus_onln;
 extern const char *input_name;
 extern bool perf_host, perf_guest;
 extern const char perf_version_string[];
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index b04c2b6b28b3..8b0cb20a770c 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1121,16 +1121,15 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
 	return 0;
 }
 
-#define MAX_CACHES (MAX_NR_CPUS * 4)
-
 static int write_cache(struct feat_fd *ff,
 		       struct evlist *evlist __maybe_unused)
 {
-	struct cpu_cache_level caches[MAX_CACHES];
+	u32 max_caches = (nr_cpus_onln * 4);
+	struct cpu_cache_level caches[max_caches];
 	u32 cnt = 0, i, version = 1;
 	int ret;
 
-	ret = build_caches(caches, MAX_CACHES, &cnt);
+	ret = build_caches(caches, max_caches, &cnt);
 	if (ret)
 		goto out;
 
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index f6ee7fbad3e4..3ad77d5e8aab 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2615,7 +2615,7 @@ 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)
+	if (cpu < 0 || cpu >= nr_cpus_onln || !machine->current_tid)
 		return -1;
 
 	return machine->current_tid[cpu];
@@ -2632,16 +2632,15 @@ 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_onln, sizeof(pid_t));
 		if (!machine->current_tid)
 			return -ENOMEM;
-		for (i = 0; i < MAX_NR_CPUS; i++)
+		for (i = 0; i < nr_cpus_onln; i++)
 			machine->current_tid[i] = -1;
 	}
 
-	if (cpu >= MAX_NR_CPUS) {
-		pr_err("Requested CPU %d too large. ", cpu);
-		pr_err("Consider raising MAX_NR_CPUS\n");
+	if (cpu >= nr_cpus_onln) {
+		pr_err("Requested CPU %d too large, there are %d CPUs currently online.\n", cpu, nr_cpus_onln);
 		return -EINVAL;
 	}
 
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index e4e4e3bf8b2b..42dddbd2f23c 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, nr_cpus_onln);
 }
 
 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(nr_cpus_onln);
 		if (!mask)
 			return -ENOMEM;
 
diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
index ae6a534a7a80..0404bd87812a 100644
--- a/tools/perf/util/svghelper.c
+++ b/tools/perf/util/svghelper.c
@@ -706,7 +706,7 @@ static void scan_thread_topology(int *map, struct topology *t, int cpu, int *pos
 
 		for_each_set_bit(thr,
 				 cpumask_bits(&t->sib_thr[i]),
-				 MAX_NR_CPUS)
+				 nr_cpus_onln)
 			if (map[thr] == -1)
 				map[thr] = (*pos)++;
 	}
@@ -721,7 +721,7 @@ static void scan_core_topology(int *map, struct topology *t)
 	for (i = 0; i < t->sib_core_nr; i++)
 		for_each_set_bit(cpu,
 				 cpumask_bits(&t->sib_core[i]),
-				 MAX_NR_CPUS)
+				 nr_cpus_onln)
 			scan_thread_topology(map, t, cpu, &pos);
 }
 
@@ -738,7 +738,7 @@ 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 >= nr_cpus_onln) {
 			ret = -1;
 			break;
 		}
@@ -785,13 +785,13 @@ int svg_build_topology_map(char *sib_core, int sib_core_nr,
 		sib_thr += strlen(sib_thr) + 1;
 	}
 
-	topology_map = malloc(sizeof(int) * MAX_NR_CPUS);
+	topology_map = malloc(sizeof(int) * nr_cpus_onln);
 	if (!topology_map) {
 		fprintf(stderr, "topology: no memory\n");
 		goto exit;
 	}
 
-	for (i = 0; i < MAX_NR_CPUS; i++)
+	for (i = 0; i < nr_cpus_onln; i++)
 		topology_map[i] = -1;
 
 	scan_core_topology(topology_map, &t);
-- 
2.12.3