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libperf cpumap: Rename perf_cpu_map__default_new() to perf_cpu_map__new_online_cpus() and prefer sysfs

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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 it 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.

Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: André Almeida <andrealmeid@igalia.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Atish Patra <atishp@rivosinc.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paran Lee <p4ranlee@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: bpf@vger.kernel.org
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20231129060211.1890454-3-irogers@google.com
[ s/syfs/sysfs/g typo ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2023-11-28 22:01:59 -08:00 committed by Arnaldo Carvalho de Melo
parent 48219b089d
commit 8f60f870a9
4 changed files with 51 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
tools/lib/perf/cpumap.c
View File

@ -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_sysfs_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_sysfs_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);

15
tools/lib/perf/include/perf/cpumap.h
View File

@ -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);

2
tools/lib/perf/libperf.map
View File

@ -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;

2
tools/lib/perf/tests/test-cpumap.c
View File

@ -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;