Commit 59f41af9 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarWang 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 98916392

tools/perf/util/llvm-utils.c

+18 −6
Original line number Diff line number Diff line
@@ -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);

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