Re: [PATCH] perf bench syscall: Add fork syscall benchmark

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Mon, Mar 20, 2023 at 11:57 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> This is a follow up patch for the execve bench which is actually
> fork + execve, it makes sense to add the fork syscall benchmark
> to compare the execve part precisely.
>
> Some archs have no __NR_fork definition which is used only as a
> check condition to call test_fork(), let us just define it as -1
> to avoid build error.
>
> Suggested-by: Namhyung Kim <namhyung@kernel.org>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung


> ---
>  tools/arch/x86/include/uapi/asm/unistd_32.h |  4 ++--
>  tools/arch/x86/include/uapi/asm/unistd_64.h |  3 +++
>  tools/perf/bench/bench.h                    |  1 +
>  tools/perf/bench/syscall.c                  | 35 +++++++++++++++++++++++++++++
>  tools/perf/builtin-bench.c                  |  1 +
>  5 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/tools/arch/x86/include/uapi/asm/unistd_32.h b/tools/arch/x86/include/uapi/asm/unistd_32.h
> index 2712d5e..b8ddfc4 100644
> --- a/tools/arch/x86/include/uapi/asm/unistd_32.h
> +++ b/tools/arch/x86/include/uapi/asm/unistd_32.h
> @@ -1,6 +1,6 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
> -#ifndef __NR_execve
> -#define __NR_execve 11
> +#ifndef __NR_fork
> +#define __NR_fork 2
>  #endif
>  #ifndef __NR_getppid
>  #define __NR_getppid 64
> diff --git a/tools/arch/x86/include/uapi/asm/unistd_64.h b/tools/arch/x86/include/uapi/asm/unistd_64.h
> index a6f7fe8..f70d2cad 100644
> --- a/tools/arch/x86/include/uapi/asm/unistd_64.h
> +++ b/tools/arch/x86/include/uapi/asm/unistd_64.h
> @@ -1,4 +1,7 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __NR_fork
> +#define __NR_fork 57
> +#endif
>  #ifndef __NR_execve
>  #define __NR_execve 59
>  #endif
> diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h
> index e438931..edfc257 100644
> --- a/tools/perf/bench/bench.h
> +++ b/tools/perf/bench/bench.h
> @@ -23,6 +23,7 @@ int bench_sched_messaging(int argc, const char **argv);
>  int bench_sched_pipe(int argc, const char **argv);
>  int bench_syscall_basic(int argc, const char **argv);
>  int bench_syscall_getpgid(int argc, const char **argv);
> +int bench_syscall_fork(int argc, const char **argv);
>  int bench_syscall_execve(int argc, const char **argv);
>  int bench_mem_memcpy(int argc, const char **argv);
>  int bench_mem_memset(int argc, const char **argv);
> diff --git a/tools/perf/bench/syscall.c b/tools/perf/bench/syscall.c
> index fe79f7f..ea4dfc07 100644
> --- a/tools/perf/bench/syscall.c
> +++ b/tools/perf/bench/syscall.c
> @@ -18,6 +18,10 @@
>  #include <unistd.h>
>  #include <stdlib.h>
>
> +#ifndef __NR_fork
> +#define __NR_fork -1
> +#endif
> +
>  #define LOOPS_DEFAULT 10000000
>  static int loops = LOOPS_DEFAULT;
>
> @@ -31,6 +35,23 @@ static const char * const bench_syscall_usage[] = {
>         NULL
>  };
>
> +static void test_fork(void)
> +{
> +       pid_t pid = fork();
> +
> +       if (pid < 0) {
> +               fprintf(stderr, "fork failed\n");
> +               exit(1);
> +       } else if (pid == 0) {
> +               exit(0);
> +       } else {
> +               if (waitpid(pid, NULL, 0) < 0) {
> +                       fprintf(stderr, "waitpid failed\n");
> +                       exit(1);
> +               }
> +       }
> +}
> +
>  static void test_execve(void)
>  {
>         const char *pathname = "/bin/true";
> @@ -71,6 +92,12 @@ static int bench_syscall_common(int argc, const char **argv, int syscall)
>                 case __NR_getpgid:
>                         getpgid(0);
>                         break;
> +               case __NR_fork:
> +                       test_fork();
> +                       /* Only loop 10000 times to save time */
> +                       if (i == 10000)
> +                               loops = 10000;
> +                       break;
>                 case __NR_execve:
>                         test_execve();
>                         /* Only loop 10000 times to save time */
> @@ -92,6 +119,9 @@ static int bench_syscall_common(int argc, const char **argv, int syscall)
>         case __NR_getpgid:
>                 name = "getpgid()";
>                 break;
> +       case __NR_fork:
> +               name = "fork()";
> +               break;
>         case __NR_execve:
>                 name = "execve()";
>                 break;
> @@ -143,6 +173,11 @@ int bench_syscall_getpgid(int argc, const char **argv)
>         return bench_syscall_common(argc, argv, __NR_getpgid);
>  }
>
> +int bench_syscall_fork(int argc, const char **argv)
> +{
> +       return bench_syscall_common(argc, argv, __NR_fork);
> +}
> +
>  int bench_syscall_execve(int argc, const char **argv)
>  {
>         return bench_syscall_common(argc, argv, __NR_execve);
> diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
> index 814e9af..d0fcc3c 100644
> --- a/tools/perf/builtin-bench.c
> +++ b/tools/perf/builtin-bench.c
> @@ -53,6 +53,7 @@ static struct bench sched_benchmarks[] = {
>  static struct bench syscall_benchmarks[] = {
>         { "basic",      "Benchmark for basic getppid(2) calls",         bench_syscall_basic     },
>         { "getpgid",    "Benchmark for getpgid(2) calls",               bench_syscall_getpgid   },
> +       { "fork",       "Benchmark for fork(2) calls",                  bench_syscall_fork      },
>         { "execve",     "Benchmark for execve(2) calls",                bench_syscall_execve    },
>         { "all",        "Run all syscall benchmarks",                   NULL                    },
>         { NULL,         NULL,                                           NULL                    },
> --
> 2.1.0
>