[v1,02/14] libperf cpumap: Rename and prefer sysfs for perf_cpu_map__default_new

Message ID 20231129060211.1890454-3-irogers@google.com
State New
Headers
Series Clean up libperf cpumap's empty function |

Commit Message

Ian Rogers Nov. 29, 2023, 6:01 a.m. UTC
  Rename perf_cpu_map__default_new to perf_cpu_map__new_online_cpus to
better indicate what the implementation does. Read the online CPUs
from /sys/devices/system/cpu/online first before using sysconf as
sysconf can't accurately configure holes in the CPU map. If sysconf is
used, warn when the configured and online processors disagree.

When reading from a file, if the read doesn't yield a CPU map then
return an empty map rather than the default online. This avoids
recursion but also better yields being able to detect failures.

Add more comments.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/perf/cpumap.c              | 59 +++++++++++++++++-----------
 tools/lib/perf/include/perf/cpumap.h | 15 ++++++-
 tools/lib/perf/libperf.map           |  2 +-
 tools/lib/perf/tests/test-cpumap.c   |  2 +-
 4 files changed, 51 insertions(+), 27 deletions(-)
  

Comments

James Clark Dec. 12, 2023, 11:32 a.m. UTC | #1
On 29/11/2023 06:01, Ian Rogers wrote:
> Rename perf_cpu_map__default_new to perf_cpu_map__new_online_cpus to
> better indicate what the implementation does. Read the online CPUs
> from /sys/devices/system/cpu/online first before using sysconf as
> sysconf can't accurately configure holes in the CPU map. If sysconf is
> used, warn when the configured and online processors disagree.
> 
> When reading from a file, if the read doesn't yield a CPU map then
> return an empty map rather than the default online. This avoids
> recursion but also better yields being able to detect failures.
> 
> Add more comments.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>

Reviewed-by: James Clark <james.clark@arm.com>

> ---
>  tools/lib/perf/cpumap.c              | 59 +++++++++++++++++-----------
>  tools/lib/perf/include/perf/cpumap.h | 15 ++++++-
>  tools/lib/perf/libperf.map           |  2 +-
>  tools/lib/perf/tests/test-cpumap.c   |  2 +-
>  4 files changed, 51 insertions(+), 27 deletions(-)
> 
> diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> index 2bd6aba3d8c9..463ca8b37d45 100644
> --- a/tools/lib/perf/cpumap.c
> +++ b/tools/lib/perf/cpumap.c
> @@ -9,6 +9,7 @@
>  #include <unistd.h>
>  #include <ctype.h>
>  #include <limits.h>
> +#include "internal.h"
>  
>  void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus)
>  {
> @@ -66,15 +67,21 @@ void perf_cpu_map__put(struct perf_cpu_map *map)
>  	}
>  }
>  
> -static struct perf_cpu_map *cpu_map__default_new(void)
> +static struct perf_cpu_map *cpu_map__new_sysconf(void)
>  {
>  	struct perf_cpu_map *cpus;
> -	int nr_cpus;
> +	int nr_cpus, nr_cpus_conf;
>  
>  	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
>  	if (nr_cpus < 0)
>  		return NULL;
>  
> +	nr_cpus_conf = sysconf(_SC_NPROCESSORS_CONF);
> +	if (nr_cpus != nr_cpus_conf) {
> +		pr_warning("Number of online CPUs (%d) differs from the number configured (%d) the CPU map will only cover the first %d CPUs.",
> +			nr_cpus, nr_cpus_conf, nr_cpus);
> +	}
> +
>  	cpus = perf_cpu_map__alloc(nr_cpus);
>  	if (cpus != NULL) {
>  		int i;
> @@ -86,9 +93,27 @@ static struct perf_cpu_map *cpu_map__default_new(void)
>  	return cpus;
>  }
>  
> -struct perf_cpu_map *perf_cpu_map__default_new(void)
> +static struct perf_cpu_map *cpu_map__new_syfs_online(void)
>  {
> -	return cpu_map__default_new();
> +	struct perf_cpu_map *cpus = NULL;
> +	FILE *onlnf;
> +
> +	onlnf = fopen("/sys/devices/system/cpu/online", "r");
> +	if (onlnf) {
> +		cpus = perf_cpu_map__read(onlnf);
> +		fclose(onlnf);
> +	}
> +	return cpus;
> +}
> +
> +struct perf_cpu_map *perf_cpu_map__new_online_cpus(void)
> +{
> +	struct perf_cpu_map *cpus = cpu_map__new_syfs_online();
> +
> +	if (cpus)
> +		return cpus;
> +
> +	return cpu_map__new_sysconf();
>  }
>  
>  
> @@ -180,27 +205,11 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
>  
>  	if (nr_cpus > 0)
>  		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
> -	else
> -		cpus = cpu_map__default_new();
>  out_free_tmp:
>  	free(tmp_cpus);
>  	return cpus;
>  }
>  
> -static struct perf_cpu_map *cpu_map__read_all_cpu_map(void)
> -{
> -	struct perf_cpu_map *cpus = NULL;
> -	FILE *onlnf;
> -
> -	onlnf = fopen("/sys/devices/system/cpu/online", "r");
> -	if (!onlnf)
> -		return cpu_map__default_new();
> -
> -	cpus = perf_cpu_map__read(onlnf);
> -	fclose(onlnf);
> -	return cpus;
> -}
> -
>  struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  {
>  	struct perf_cpu_map *cpus = NULL;
> @@ -211,7 +220,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  	int max_entries = 0;
>  
>  	if (!cpu_list)
> -		return cpu_map__read_all_cpu_map();
> +		return perf_cpu_map__new_online_cpus();
>  
>  	/*
>  	 * must handle the case of empty cpumap to cover
> @@ -268,9 +277,11 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  
>  	if (nr_cpus > 0)
>  		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
> -	else if (*cpu_list != '\0')
> -		cpus = cpu_map__default_new();
> -	else
> +	else if (*cpu_list != '\0') {
> +		pr_warning("Unexpected characters at end of cpu list ('%s'), using online CPUs.",
> +			   cpu_list);
> +		cpus = perf_cpu_map__new_online_cpus();
> +	} else
>  		cpus = perf_cpu_map__new_any_cpu();
>  invalid:
>  	free(tmp_cpus);
> diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h
> index d0bf218ada11..b24bd8b8f34e 100644
> --- a/tools/lib/perf/include/perf/cpumap.h
> +++ b/tools/lib/perf/include/perf/cpumap.h
> @@ -22,7 +22,20 @@ struct perf_cpu_map;
>   * perf_cpu_map__new_any_cpu - a map with a singular "any CPU"/dummy -1 value.
>   */
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_any_cpu(void);
> -LIBPERF_API struct perf_cpu_map *perf_cpu_map__default_new(void);
> +/**
> + * perf_cpu_map__new_online_cpus - a map read from
> + *                                 /sys/devices/system/cpu/online if
> + *                                 available. If reading wasn't possible a map
> + *                                 is created using the online processors
> + *                                 assuming the first 'n' processors are all
> + *                                 online.
> + */
> +LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_online_cpus(void);
> +/**
> + * perf_cpu_map__new - create a map from the given cpu_list such as "0-7". If no
> + *                     cpu_list argument is provided then
> + *                     perf_cpu_map__new_online_cpus is returned.
> + */
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list);
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__read(FILE *file);
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map);
> diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
> index a8ff64baea3e..8a71f841498e 100644
> --- a/tools/lib/perf/libperf.map
> +++ b/tools/lib/perf/libperf.map
> @@ -2,7 +2,7 @@ LIBPERF_0.0.1 {
>  	global:
>  		libperf_init;
>  		perf_cpu_map__new_any_cpu;
> -		perf_cpu_map__default_new;
> +		perf_cpu_map__new_online_cpus;
>  		perf_cpu_map__get;
>  		perf_cpu_map__put;
>  		perf_cpu_map__new;
> diff --git a/tools/lib/perf/tests/test-cpumap.c b/tools/lib/perf/tests/test-cpumap.c
> index 2c359bdb951e..c998b1dae863 100644
> --- a/tools/lib/perf/tests/test-cpumap.c
> +++ b/tools/lib/perf/tests/test-cpumap.c
> @@ -29,7 +29,7 @@ int test_cpumap(int argc, char **argv)
>  	perf_cpu_map__put(cpus);
>  	perf_cpu_map__put(cpus);
>  
> -	cpus = perf_cpu_map__default_new();
> +	cpus = perf_cpu_map__new_online_cpus();
>  	if (!cpus)
>  		return -1;
>
  
Arnaldo Carvalho de Melo Dec. 12, 2023, 5:39 p.m. UTC | #2
Em Tue, Nov 28, 2023 at 10:01:59PM -0800, Ian Rogers escreveu:
> Rename perf_cpu_map__default_new to perf_cpu_map__new_online_cpus to
> better indicate what the implementation does. Read the online CPUs
> from /sys/devices/system/cpu/online first before using sysconf as
> sysconf can't accurately configure holes in the CPU map. If sysconf is
> used, warn when the configured and online processors disagree.
> 
> When reading from a file, if the read doesn't yield a CPU map then
> return an empty map rather than the default online. This avoids
> recursion but also better yields being able to detect failures.
> 
> Add more comments.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/lib/perf/cpumap.c              | 59 +++++++++++++++++-----------
>  tools/lib/perf/include/perf/cpumap.h | 15 ++++++-
>  tools/lib/perf/libperf.map           |  2 +-
>  tools/lib/perf/tests/test-cpumap.c   |  2 +-
>  4 files changed, 51 insertions(+), 27 deletions(-)
> 
> diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> index 2bd6aba3d8c9..463ca8b37d45 100644
> --- a/tools/lib/perf/cpumap.c
> +++ b/tools/lib/perf/cpumap.c
> @@ -9,6 +9,7 @@
>  #include <unistd.h>
>  #include <ctype.h>
>  #include <limits.h>
> +#include "internal.h"
>  
>  void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus)
>  {
> @@ -66,15 +67,21 @@ void perf_cpu_map__put(struct perf_cpu_map *map)
>  	}
>  }
>  
> -static struct perf_cpu_map *cpu_map__default_new(void)
> +static struct perf_cpu_map *cpu_map__new_sysconf(void)
>  {
>  	struct perf_cpu_map *cpus;
> -	int nr_cpus;
> +	int nr_cpus, nr_cpus_conf;
>  
>  	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
>  	if (nr_cpus < 0)
>  		return NULL;
>  
> +	nr_cpus_conf = sysconf(_SC_NPROCESSORS_CONF);
> +	if (nr_cpus != nr_cpus_conf) {
> +		pr_warning("Number of online CPUs (%d) differs from the number configured (%d) the CPU map will only cover the first %d CPUs.",
> +			nr_cpus, nr_cpus_conf, nr_cpus);
> +	}
> +
>  	cpus = perf_cpu_map__alloc(nr_cpus);
>  	if (cpus != NULL) {
>  		int i;
> @@ -86,9 +93,27 @@ static struct perf_cpu_map *cpu_map__default_new(void)
>  	return cpus;
>  }
>  
> -struct perf_cpu_map *perf_cpu_map__default_new(void)
> +static struct perf_cpu_map *cpu_map__new_syfs_online(void)

I'm renaming this to cpu_map__new_sysfs_online(), ok?

- Arnaldo

>  {
> -	return cpu_map__default_new();
> +	struct perf_cpu_map *cpus = NULL;
> +	FILE *onlnf;
> +
> +	onlnf = fopen("/sys/devices/system/cpu/online", "r");
> +	if (onlnf) {
> +		cpus = perf_cpu_map__read(onlnf);
> +		fclose(onlnf);
> +	}
> +	return cpus;
> +}
> +
> +struct perf_cpu_map *perf_cpu_map__new_online_cpus(void)
> +{
> +	struct perf_cpu_map *cpus = cpu_map__new_syfs_online();
> +
> +	if (cpus)
> +		return cpus;
> +
> +	return cpu_map__new_sysconf();
>  }
>  
>  
> @@ -180,27 +205,11 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
>  
>  	if (nr_cpus > 0)
>  		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
> -	else
> -		cpus = cpu_map__default_new();
>  out_free_tmp:
>  	free(tmp_cpus);
>  	return cpus;
>  }
>  
> -static struct perf_cpu_map *cpu_map__read_all_cpu_map(void)
> -{
> -	struct perf_cpu_map *cpus = NULL;
> -	FILE *onlnf;
> -
> -	onlnf = fopen("/sys/devices/system/cpu/online", "r");
> -	if (!onlnf)
> -		return cpu_map__default_new();
> -
> -	cpus = perf_cpu_map__read(onlnf);
> -	fclose(onlnf);
> -	return cpus;
> -}
> -
>  struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  {
>  	struct perf_cpu_map *cpus = NULL;
> @@ -211,7 +220,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  	int max_entries = 0;
>  
>  	if (!cpu_list)
> -		return cpu_map__read_all_cpu_map();
> +		return perf_cpu_map__new_online_cpus();
>  
>  	/*
>  	 * must handle the case of empty cpumap to cover
> @@ -268,9 +277,11 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
>  
>  	if (nr_cpus > 0)
>  		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
> -	else if (*cpu_list != '\0')
> -		cpus = cpu_map__default_new();
> -	else
> +	else if (*cpu_list != '\0') {
> +		pr_warning("Unexpected characters at end of cpu list ('%s'), using online CPUs.",
> +			   cpu_list);
> +		cpus = perf_cpu_map__new_online_cpus();
> +	} else
>  		cpus = perf_cpu_map__new_any_cpu();
>  invalid:
>  	free(tmp_cpus);
> diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h
> index d0bf218ada11..b24bd8b8f34e 100644
> --- a/tools/lib/perf/include/perf/cpumap.h
> +++ b/tools/lib/perf/include/perf/cpumap.h
> @@ -22,7 +22,20 @@ struct perf_cpu_map;
>   * perf_cpu_map__new_any_cpu - a map with a singular "any CPU"/dummy -1 value.
>   */
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_any_cpu(void);
> -LIBPERF_API struct perf_cpu_map *perf_cpu_map__default_new(void);
> +/**
> + * perf_cpu_map__new_online_cpus - a map read from
> + *                                 /sys/devices/system/cpu/online if
> + *                                 available. If reading wasn't possible a map
> + *                                 is created using the online processors
> + *                                 assuming the first 'n' processors are all
> + *                                 online.
> + */
> +LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_online_cpus(void);
> +/**
> + * perf_cpu_map__new - create a map from the given cpu_list such as "0-7". If no
> + *                     cpu_list argument is provided then
> + *                     perf_cpu_map__new_online_cpus is returned.
> + */
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list);
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__read(FILE *file);
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map);
> diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
> index a8ff64baea3e..8a71f841498e 100644
> --- a/tools/lib/perf/libperf.map
> +++ b/tools/lib/perf/libperf.map
> @@ -2,7 +2,7 @@ LIBPERF_0.0.1 {
>  	global:
>  		libperf_init;
>  		perf_cpu_map__new_any_cpu;
> -		perf_cpu_map__default_new;
> +		perf_cpu_map__new_online_cpus;
>  		perf_cpu_map__get;
>  		perf_cpu_map__put;
>  		perf_cpu_map__new;
> diff --git a/tools/lib/perf/tests/test-cpumap.c b/tools/lib/perf/tests/test-cpumap.c
> index 2c359bdb951e..c998b1dae863 100644
> --- a/tools/lib/perf/tests/test-cpumap.c
> +++ b/tools/lib/perf/tests/test-cpumap.c
> @@ -29,7 +29,7 @@ int test_cpumap(int argc, char **argv)
>  	perf_cpu_map__put(cpus);
>  	perf_cpu_map__put(cpus);
>  
> -	cpus = perf_cpu_map__default_new();
> +	cpus = perf_cpu_map__new_online_cpus();
>  	if (!cpus)
>  		return -1;
>  
> -- 
> 2.43.0.rc1.413.gea7ed67945-goog
>
  
Ian Rogers Dec. 12, 2023, 5:52 p.m. UTC | #3
On Tue, Dec 12, 2023 at 9:39 AM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Tue, Nov 28, 2023 at 10:01:59PM -0800, Ian Rogers escreveu:
> > Rename perf_cpu_map__default_new to perf_cpu_map__new_online_cpus to
> > better indicate what the implementation does. Read the online CPUs
> > from /sys/devices/system/cpu/online first before using sysconf as
> > sysconf can't accurately configure holes in the CPU map. If sysconf is
> > used, warn when the configured and online processors disagree.
> >
> > When reading from a file, if the read doesn't yield a CPU map then
> > return an empty map rather than the default online. This avoids
> > recursion but also better yields being able to detect failures.
> >
> > Add more comments.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/lib/perf/cpumap.c              | 59 +++++++++++++++++-----------
> >  tools/lib/perf/include/perf/cpumap.h | 15 ++++++-
> >  tools/lib/perf/libperf.map           |  2 +-
> >  tools/lib/perf/tests/test-cpumap.c   |  2 +-
> >  4 files changed, 51 insertions(+), 27 deletions(-)
> >
> > diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> > index 2bd6aba3d8c9..463ca8b37d45 100644
> > --- a/tools/lib/perf/cpumap.c
> > +++ b/tools/lib/perf/cpumap.c
> > @@ -9,6 +9,7 @@
> >  #include <unistd.h>
> >  #include <ctype.h>
> >  #include <limits.h>
> > +#include "internal.h"
> >
> >  void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus)
> >  {
> > @@ -66,15 +67,21 @@ void perf_cpu_map__put(struct perf_cpu_map *map)
> >       }
> >  }
> >
> > -static struct perf_cpu_map *cpu_map__default_new(void)
> > +static struct perf_cpu_map *cpu_map__new_sysconf(void)
> >  {
> >       struct perf_cpu_map *cpus;
> > -     int nr_cpus;
> > +     int nr_cpus, nr_cpus_conf;
> >
> >       nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
> >       if (nr_cpus < 0)
> >               return NULL;
> >
> > +     nr_cpus_conf = sysconf(_SC_NPROCESSORS_CONF);
> > +     if (nr_cpus != nr_cpus_conf) {
> > +             pr_warning("Number of online CPUs (%d) differs from the number configured (%d) the CPU map will only cover the first %d CPUs.",
> > +                     nr_cpus, nr_cpus_conf, nr_cpus);
> > +     }
> > +
> >       cpus = perf_cpu_map__alloc(nr_cpus);
> >       if (cpus != NULL) {
> >               int i;
> > @@ -86,9 +93,27 @@ static struct perf_cpu_map *cpu_map__default_new(void)
> >       return cpus;
> >  }
> >
> > -struct perf_cpu_map *perf_cpu_map__default_new(void)
> > +static struct perf_cpu_map *cpu_map__new_syfs_online(void)
>
> I'm renaming this to cpu_map__new_sysfs_online(), ok?

Yep, typo. Thanks!

Ian

> - Arnaldo
>
> >  {
> > -     return cpu_map__default_new();
> > +     struct perf_cpu_map *cpus = NULL;
> > +     FILE *onlnf;
> > +
> > +     onlnf = fopen("/sys/devices/system/cpu/online", "r");
> > +     if (onlnf) {
> > +             cpus = perf_cpu_map__read(onlnf);
> > +             fclose(onlnf);
> > +     }
> > +     return cpus;
> > +}
> > +
> > +struct perf_cpu_map *perf_cpu_map__new_online_cpus(void)
> > +{
> > +     struct perf_cpu_map *cpus = cpu_map__new_syfs_online();
> > +
> > +     if (cpus)
> > +             return cpus;
> > +
> > +     return cpu_map__new_sysconf();
> >  }
> >
> >
> > @@ -180,27 +205,11 @@ struct perf_cpu_map *perf_cpu_map__read(FILE *file)
> >
> >       if (nr_cpus > 0)
> >               cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
> > -     else
> > -             cpus = cpu_map__default_new();
> >  out_free_tmp:
> >       free(tmp_cpus);
> >       return cpus;
> >  }
> >
> > -static struct perf_cpu_map *cpu_map__read_all_cpu_map(void)
> > -{
> > -     struct perf_cpu_map *cpus = NULL;
> > -     FILE *onlnf;
> > -
> > -     onlnf = fopen("/sys/devices/system/cpu/online", "r");
> > -     if (!onlnf)
> > -             return cpu_map__default_new();
> > -
> > -     cpus = perf_cpu_map__read(onlnf);
> > -     fclose(onlnf);
> > -     return cpus;
> > -}
> > -
> >  struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
> >  {
> >       struct perf_cpu_map *cpus = NULL;
> > @@ -211,7 +220,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
> >       int max_entries = 0;
> >
> >       if (!cpu_list)
> > -             return cpu_map__read_all_cpu_map();
> > +             return perf_cpu_map__new_online_cpus();
> >
> >       /*
> >        * must handle the case of empty cpumap to cover
> > @@ -268,9 +277,11 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
> >
> >       if (nr_cpus > 0)
> >               cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
> > -     else if (*cpu_list != '\0')
> > -             cpus = cpu_map__default_new();
> > -     else
> > +     else if (*cpu_list != '\0') {
> > +             pr_warning("Unexpected characters at end of cpu list ('%s'), using online CPUs.",
> > +                        cpu_list);
> > +             cpus = perf_cpu_map__new_online_cpus();
> > +     } else
> >               cpus = perf_cpu_map__new_any_cpu();
> >  invalid:
> >       free(tmp_cpus);
> > diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h
> > index d0bf218ada11..b24bd8b8f34e 100644
> > --- a/tools/lib/perf/include/perf/cpumap.h
> > +++ b/tools/lib/perf/include/perf/cpumap.h
> > @@ -22,7 +22,20 @@ struct perf_cpu_map;
> >   * perf_cpu_map__new_any_cpu - a map with a singular "any CPU"/dummy -1 value.
> >   */
> >  LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_any_cpu(void);
> > -LIBPERF_API struct perf_cpu_map *perf_cpu_map__default_new(void);
> > +/**
> > + * perf_cpu_map__new_online_cpus - a map read from
> > + *                                 /sys/devices/system/cpu/online if
> > + *                                 available. If reading wasn't possible a map
> > + *                                 is created using the online processors
> > + *                                 assuming the first 'n' processors are all
> > + *                                 online.
> > + */
> > +LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_online_cpus(void);
> > +/**
> > + * perf_cpu_map__new - create a map from the given cpu_list such as "0-7". If no
> > + *                     cpu_list argument is provided then
> > + *                     perf_cpu_map__new_online_cpus is returned.
> > + */
> >  LIBPERF_API struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list);
> >  LIBPERF_API struct perf_cpu_map *perf_cpu_map__read(FILE *file);
> >  LIBPERF_API struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map);
> > diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
> > index a8ff64baea3e..8a71f841498e 100644
> > --- a/tools/lib/perf/libperf.map
> > +++ b/tools/lib/perf/libperf.map
> > @@ -2,7 +2,7 @@ LIBPERF_0.0.1 {
> >       global:
> >               libperf_init;
> >               perf_cpu_map__new_any_cpu;
> > -             perf_cpu_map__default_new;
> > +             perf_cpu_map__new_online_cpus;
> >               perf_cpu_map__get;
> >               perf_cpu_map__put;
> >               perf_cpu_map__new;
> > diff --git a/tools/lib/perf/tests/test-cpumap.c b/tools/lib/perf/tests/test-cpumap.c
> > index 2c359bdb951e..c998b1dae863 100644
> > --- a/tools/lib/perf/tests/test-cpumap.c
> > +++ b/tools/lib/perf/tests/test-cpumap.c
> > @@ -29,7 +29,7 @@ int test_cpumap(int argc, char **argv)
> >       perf_cpu_map__put(cpus);
> >       perf_cpu_map__put(cpus);
> >
> > -     cpus = perf_cpu_map__default_new();
> > +     cpus = perf_cpu_map__new_online_cpus();
> >       if (!cpus)
> >               return -1;
> >
> > --
> > 2.43.0.rc1.413.gea7ed67945-goog
> >
>
> --
>
> - Arnaldo
  

Patch

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index 2bd6aba3d8c9..463ca8b37d45 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -9,6 +9,7 @@ 
 #include <unistd.h>
 #include <ctype.h>
 #include <limits.h>
+#include "internal.h"
 
 void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus)
 {
@@ -66,15 +67,21 @@  void perf_cpu_map__put(struct perf_cpu_map *map)
 	}
 }
 
-static struct perf_cpu_map *cpu_map__default_new(void)
+static struct perf_cpu_map *cpu_map__new_sysconf(void)
 {
 	struct perf_cpu_map *cpus;
-	int nr_cpus;
+	int nr_cpus, nr_cpus_conf;
 
 	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 	if (nr_cpus < 0)
 		return NULL;
 
+	nr_cpus_conf = sysconf(_SC_NPROCESSORS_CONF);
+	if (nr_cpus != nr_cpus_conf) {
+		pr_warning("Number of online CPUs (%d) differs from the number configured (%d) the CPU map will only cover the first %d CPUs.",
+			nr_cpus, nr_cpus_conf, nr_cpus);
+	}
+
 	cpus = perf_cpu_map__alloc(nr_cpus);
 	if (cpus != NULL) {
 		int i;
@@ -86,9 +93,27 @@  static struct perf_cpu_map *cpu_map__default_new(void)
 	return cpus;
 }
 
-struct perf_cpu_map *perf_cpu_map__default_new(void)
+static struct perf_cpu_map *cpu_map__new_syfs_online(void)
 {
-	return cpu_map__default_new();
+	struct perf_cpu_map *cpus = NULL;
+	FILE *onlnf;
+
+	onlnf = fopen("/sys/devices/system/cpu/online", "r");
+	if (onlnf) {
+		cpus = perf_cpu_map__read(onlnf);
+		fclose(onlnf);
+	}
+	return cpus;
+}
+
+struct perf_cpu_map *perf_cpu_map__new_online_cpus(void)
+{
+	struct perf_cpu_map *cpus = cpu_map__new_syfs_online();
+
+	if (cpus)
+		return cpus;
+
+	return cpu_map__new_sysconf();
 }
 
 
@@ -180,27 +205,11 @@  struct perf_cpu_map *perf_cpu_map__read(FILE *file)
 
 	if (nr_cpus > 0)
 		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
-	else
-		cpus = cpu_map__default_new();
 out_free_tmp:
 	free(tmp_cpus);
 	return cpus;
 }
 
-static struct perf_cpu_map *cpu_map__read_all_cpu_map(void)
-{
-	struct perf_cpu_map *cpus = NULL;
-	FILE *onlnf;
-
-	onlnf = fopen("/sys/devices/system/cpu/online", "r");
-	if (!onlnf)
-		return cpu_map__default_new();
-
-	cpus = perf_cpu_map__read(onlnf);
-	fclose(onlnf);
-	return cpus;
-}
-
 struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
 {
 	struct perf_cpu_map *cpus = NULL;
@@ -211,7 +220,7 @@  struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
 	int max_entries = 0;
 
 	if (!cpu_list)
-		return cpu_map__read_all_cpu_map();
+		return perf_cpu_map__new_online_cpus();
 
 	/*
 	 * must handle the case of empty cpumap to cover
@@ -268,9 +277,11 @@  struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
 
 	if (nr_cpus > 0)
 		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
-	else if (*cpu_list != '\0')
-		cpus = cpu_map__default_new();
-	else
+	else if (*cpu_list != '\0') {
+		pr_warning("Unexpected characters at end of cpu list ('%s'), using online CPUs.",
+			   cpu_list);
+		cpus = perf_cpu_map__new_online_cpus();
+	} else
 		cpus = perf_cpu_map__new_any_cpu();
 invalid:
 	free(tmp_cpus);
diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h
index d0bf218ada11..b24bd8b8f34e 100644
--- a/tools/lib/perf/include/perf/cpumap.h
+++ b/tools/lib/perf/include/perf/cpumap.h
@@ -22,7 +22,20 @@  struct perf_cpu_map;
  * perf_cpu_map__new_any_cpu - a map with a singular "any CPU"/dummy -1 value.
  */
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_any_cpu(void);
-LIBPERF_API struct perf_cpu_map *perf_cpu_map__default_new(void);
+/**
+ * perf_cpu_map__new_online_cpus - a map read from
+ *                                 /sys/devices/system/cpu/online if
+ *                                 available. If reading wasn't possible a map
+ *                                 is created using the online processors
+ *                                 assuming the first 'n' processors are all
+ *                                 online.
+ */
+LIBPERF_API struct perf_cpu_map *perf_cpu_map__new_online_cpus(void);
+/**
+ * perf_cpu_map__new - create a map from the given cpu_list such as "0-7". If no
+ *                     cpu_list argument is provided then
+ *                     perf_cpu_map__new_online_cpus is returned.
+ */
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list);
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__read(FILE *file);
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map);
diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
index a8ff64baea3e..8a71f841498e 100644
--- a/tools/lib/perf/libperf.map
+++ b/tools/lib/perf/libperf.map
@@ -2,7 +2,7 @@  LIBPERF_0.0.1 {
 	global:
 		libperf_init;
 		perf_cpu_map__new_any_cpu;
-		perf_cpu_map__default_new;
+		perf_cpu_map__new_online_cpus;
 		perf_cpu_map__get;
 		perf_cpu_map__put;
 		perf_cpu_map__new;
diff --git a/tools/lib/perf/tests/test-cpumap.c b/tools/lib/perf/tests/test-cpumap.c
index 2c359bdb951e..c998b1dae863 100644
--- a/tools/lib/perf/tests/test-cpumap.c
+++ b/tools/lib/perf/tests/test-cpumap.c
@@ -29,7 +29,7 @@  int test_cpumap(int argc, char **argv)
 	perf_cpu_map__put(cpus);
 	perf_cpu_map__put(cpus);
 
-	cpus = perf_cpu_map__default_new();
+	cpus = perf_cpu_map__new_online_cpus();
 	if (!cpus)
 		return -1;