[PATCH v3 bpf-next] scripts/pahole-flags.sh: Parse DWARF and generate BTF with multithreading.

[Kui-Feng Lee <kuifeng@fb.com>]

Pass a "-j" argument to pahole if possible to reduce the time of
generating BTF info.

Since v1.22, pahole can parse DWARF and generate BTF with
multithreading to speed up the conversion.  It will reduce the overall
build time of the kernel for seconds.

v3 fixes whitespaces and improves the commit description.
v2 checks the version of pahole to enable multithreading only if possible.

[v2] https://lore.kernel.org/bpf/20220216193431.2691015-1-kuifeng@fb.com/
[v1] https://lore.kernel.org/bpf/20220216004616.2079689-1-kuifeng@fb.com/

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
 scripts/pahole-flags.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh
index c293941612e7..0d99ef17e4a5 100755
--- a/scripts/pahole-flags.sh
+++ b/scripts/pahole-flags.sh
@@ -16,5 +16,8 @@ fi
 if [ "${pahole_ver}" -ge "121" ]; then
 	extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
 fi
+if [ "${pahole_ver}" -ge "122" ]; then
+	extra_paholeopt="${extra_paholeopt} -j"
+fi
 
 echo ${extra_paholeopt}
-- 
2.30.2