From d21832e212d2613c0a0f3e5f09967cb3402c8a53 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 1 Jun 2017 16:57:07 +0200 Subject: kbuild: speed up checksyscalls.sh checksyscalls.sh is run at every "make" run while building the kernel, even if no files have changed. I looked at where we spend time in a trivial empty rebuild and found checksyscalls.sh to be a source of noticeable overhead, as it spawns a lot of child processes just to call 'cat' copying from stdin to stdout, once for each of the over 400 x86 syscalls. Using a shell-builtin (echo) instead of the external command gives us a 13x speedup: Before After real 0m1.018s real 0m0.077s user 0m0.068s user 0m0.048s sys 0m0.156s sys 0m0.024s The time it took to rebuild a single file on my machine dropped from 5.5 seconds to 4.5 seconds. Signed-off-by: Arnd Bergmann Signed-off-by: Masahiro Yamada --- scripts/checksyscalls.sh | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'scripts/checksyscalls.sh') diff --git a/scripts/checksyscalls.sh b/scripts/checksyscalls.sh index 116b7735ee9f..5a387a264201 100755 --- a/scripts/checksyscalls.sh +++ b/scripts/checksyscalls.sh @@ -202,15 +202,12 @@ EOF } syscall_list() { - grep '^[0-9]' "$1" | sort -n | ( + grep '^[0-9]' "$1" | sort -n | while read nr abi name entry ; do - cat <