From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7A455D3; Tue, 12 Dec 2023 03:32:58 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8269A143D; Tue, 12 Dec 2023 03:33:44 -0800 (PST) Received: from [192.168.1.3] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5D8943F762; Tue, 12 Dec 2023 03:32:53 -0800 (PST) Message-ID: Date: Tue, 12 Dec 2023 11:32:49 +0000 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v1 02/14] libperf cpumap: Rename and prefer sysfs for perf_cpu_map__default_new Content-Language: en-US To: Ian Rogers References: <20231129060211.1890454-1-irogers@google.com> <20231129060211.1890454-3-irogers@google.com> Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Adrian Hunter , Suzuki K Poulose , Mike Leach , Leo Yan , John Garry , Will Deacon , Thomas Gleixner , Darren Hart , Davidlohr Bueso , =?UTF-8?Q?Andr=c3=a9_Almeida?= , Kan Liang , K Prateek Nayak , Sean Christopherson , Paolo Bonzini , Kajol Jain , Athira Rajeev , Andrew Jones , Alexandre Ghiti , Atish Patra , "Steinar H. Gunderson" , Yang Jihong , Yang Li , Changbin Du , Sandipan Das , Ravi Bangoria , Paran Lee , Nick Desaulniers , Huacai Chen , Yanteng Si , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, bpf@vger.kernel.org From: James Clark In-Reply-To: <20231129060211.1890454-3-irogers@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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 Reviewed-by: James Clark > --- > 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 > #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_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; >