Messages in this thread Patch in this message | | | Date | Wed, 4 Nov 2015 19:09:53 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 1/4] perf tools: Pass available CPU number to clang compiler |
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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 <wangnan0@huawei.com> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Alexei Starovoitov <ast@kernel.org> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Zefan Li <lizefan@huawei.com> > Cc: pi3orama@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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