Em Wed, Nov 04, 2015 at 11:20:04AM +0000, Wang Nan escreveu:
> This patch introduces a new macro "__NR_CPUS__" to perf's embedded
> clang compiler, which represent the available CPU counters in this
available "CPU counters"? ENOPARSE :-)
> system. BPF program can use this macro to create a map with same
> number of system CPUs. For exmaple:
example
>
> struct bpf_map_def SEC("maps") pmu_map = {
> .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
> .key_size = sizeof(int),
> .value_size = sizeof(u32),
> .max_entries = __NR_CPUS__,
> };
I wonder if we shouldn't use the getconf() parameter here, i.e. define
_SC_NPROCESSORS_CONF and also provide _SC_NPROCESSORS_ONLN.
The kernel uses NR_CPUS, for accessing CONFIG_NR_CPUS, Alexei, what do
you think?
- Arnaldo
> Signed-off-by: Wang Nan <wangn...@huawei.com>
> Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
> Cc: Alexei Starovoitov <a...@kernel.org>
> Cc: Namhyung Kim <namhy...@kernel.org>
> Cc: Zefan Li <lize...@huawei.com>
> Cc: pi3or...@163.com
> ---
> tools/perf/util/llvm-utils.c | 24 ++++++++++++++++++------
> 1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
> index 4f6a478..80eecef 100644
> --- a/tools/perf/util/llvm-utils.c
> +++ b/tools/perf/util/llvm-utils.c
> @@ -11,10 +11,11 @@
> #include "cache.h"
>
> #define CLANG_BPF_CMD_DEFAULT_TEMPLATE \
> - "$CLANG_EXEC -D__KERNEL__ $CLANG_OPTIONS " \
> - "$KERNEL_INC_OPTIONS -Wno-unused-value " \
> - "-Wno-pointer-sign -working-directory " \
> - "$WORKING_DIR -c \"$CLANG_SOURCE\" -target bpf -O2 -o -"
> + "$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
> + "$CLANG_OPTIONS $KERNEL_INC_OPTIONS " \
> + "-Wno-unused-value -Wno-pointer-sign " \
> + "-working-directory $WORKING_DIR " \
> + "-c \"$CLANG_SOURCE\" -target bpf -O2 -o -"
>
> struct llvm_param llvm_param = {
> .clang_path = "clang",
> @@ -326,8 +327,8 @@ get_kbuild_opts(char **kbuild_dir, char
> **kbuild_include_opts)
> int llvm__compile_bpf(const char *path, void **p_obj_buf,
> size_t *p_obj_buf_sz)
> {
> - int err;
> - char clang_path[PATH_MAX];
> + int err, nr_cpus_avail;
> + char clang_path[PATH_MAX], nr_cpus_avail_str[64];
> const char *clang_opt = llvm_param.clang_opt;
> const char *template = llvm_param.clang_bpf_cmd_template;
> char *kbuild_dir = NULL, *kbuild_include_opts = NULL;
> @@ -354,6 +355,17 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
> */
> get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);
>
> + nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
> + if (nr_cpus_avail <= 0) {
> + pr_err(
> +"WARNING:\tunable to get available CPUs in this system: %s\n"
> +" \tUse 128 instead.\n", strerror(errno));
> + nr_cpus_avail = 128;
> + }
> + snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
> + nr_cpus_avail);
> +
> + force_set_env("NR_CPUS", nr_cpus_avail_str);
> force_set_env("CLANG_EXEC", clang_path);
> force_set_env("CLANG_OPTIONS", clang_opt);
> force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);
> --
> 1.8.3.4
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