From 8f60f870a9af53295ab4301da05ca453f115a6b6 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Tue, 28 Nov 2023 22:01:59 -0800 Subject: libperf cpumap: Rename perf_cpu_map__default_new() to perf_cpu_map__new_online_cpus() and prefer sysfs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Andrew Jones Cc: André Almeida Cc: Athira Jajeev Cc: Atish Patra Cc: Changbin Du Cc: Darren Hart Cc: Davidlohr Bueso Cc: Huacai Chen Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Garry Cc: K Prateek Nayak Cc: Kajol Jain Cc: Kan Liang Cc: Leo Yan Cc: Mark Rutland Cc: Mike Leach Cc: Namhyung Kim Cc: Nick Desaulniers Cc: Paolo Bonzini Cc: Paran Lee Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Sandipan Das Cc: Sean Christopherson Cc: Steinar H. Gunderson Cc: Suzuki Poulouse Cc: Thomas Gleixner Cc: Will Deacon Cc: Yang Jihong Cc: Yang Li Cc: Yanteng Si 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 --- 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(-) (limited to 'tools/lib') diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c index 2bd6aba3d8c9..3aa80d0d26e8 100644 --- a/tools/lib/perf/cpumap.c +++ b/tools/lib/perf/cpumap.c @@ -9,6 +9,7 @@ #include #include #include +#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); 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; -- cgit v1.2.3