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perf llvm: Pass number of configured CPUs to clang compiler 

This patch introduces a new macro "__NR_CPUS__" to perf's embedded clang
compiler, which represent the number of configured CPUs in this system.
BPF programs can use this macro to create a map with the same number of
system CPUs. For 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__,
 };

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1446636007-239722-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2015-11-04 11:20:04 +00:00 committed by Arnaldo Carvalho de Melo
parent 98916392a0
commit 59f41af980
1 changed files with 18 additions and 6 deletions
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24
tools/perf/util/llvm-utils.c
View File

@ -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);