Python 3.13 added os.process_cpu_count as a cross-platform alternative
for the Linux-only os.sched_getaffinity. Use it when it's available and
provide a fallback when it's not.

This allows kunit to run on macOS.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 tools/testing/kunit/kunit.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
index bc74088c458aee20b1a21fdeb9f3cb01ab20fec4..3a8cbb868ac559f68d047e38be92f7c64a3314ea 100755
--- a/tools/testing/kunit/kunit.py
+++ b/tools/testing/kunit/kunit.py
@@ -303,7 +303,16 @@ def massage_argv(argv: Sequence[str]) -> Sequence[str]:
 	return list(map(massage_arg, argv))
 
 def get_default_jobs() -> int:
-	return len(os.sched_getaffinity(0))
+	if sys.version_info >= (3, 13):
+		if (ncpu := os.process_cpu_count()) is not None:
+			return ncpu
+		raise RuntimeError("os.process_cpu_count() returned None")
+	 # See https://github.com/python/cpython/blob/b61fece/Lib/os.py#L1175-L1186.
+	if sys.platform != "darwin":
+		return len(os.sched_getaffinity(0))
+	if (ncpu := os.cpu_count()) is not None:
+		return ncpu
+	raise RuntimeError("os.cpu_count() returned None")
 
 def add_common_opts(parser: argparse.ArgumentParser) -> None:
 	parser.add_argument('--build_dir',

-- 
2.47.0

On Sat, 2 Nov 2024 at 20:10, Tamir Duberstein <tamird@gmail.com> wrote:
>
> Python 3.13 added os.process_cpu_count as a cross-platform alternative
> for the Linux-only os.sched_getaffinity. Use it when it's available and
> provide a fallback when it's not.
>
> This allows kunit to run on macOS.
>
> Signed-off-by: Tamir Duberstein <tamird@gmail.com>
> ---

Looks plausible enough to me. Thanks very much!

Reviewed-by: David Gow <davidgow@google.com>

Cheers,
-- David

>  tools/testing/kunit/kunit.py | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
> index bc74088c458aee20b1a21fdeb9f3cb01ab20fec4..3a8cbb868ac559f68d047e38be92f7c64a3314ea 100755
> --- a/tools/testing/kunit/kunit.py
> +++ b/tools/testing/kunit/kunit.py
> @@ -303,7 +303,16 @@ def massage_argv(argv: Sequence[str]) -> Sequence[str]:
>         return list(map(massage_arg, argv))
>
>  def get_default_jobs() -> int:
> -       return len(os.sched_getaffinity(0))
> +       if sys.version_info >= (3, 13):
> +               if (ncpu := os.process_cpu_count()) is not None:
> +                       return ncpu
> +               raise RuntimeError("os.process_cpu_count() returned None")
> +        # See https://github.com/python/cpython/blob/b61fece/Lib/os.py#L1175-L1186.
> +       if sys.platform != "darwin":
> +               return len(os.sched_getaffinity(0))
> +       if (ncpu := os.cpu_count()) is not None:
> +               return ncpu
> +       raise RuntimeError("os.cpu_count() returned None")
>
>  def add_common_opts(parser: argparse.ArgumentParser) -> None:
>         parser.add_argument('--build_dir',
>
> --
> 2.47.0
>