From d19e435ff9a4716e890d2653af6a1231d8961e37 Mon Sep 17 00:00:00 2001 From: "Carsten Haitzler (Rasterman)" Date: Fri, 26 Jul 2019 10:15:47 +0100 Subject: reduce syscalls on opening files - roll CLOEXEC into open on linux open supports() O_CLOEXEC. add test case for this in meson build and ifdef. this rolls 3 syscalls into 1 as we were doing open, then fnctl to get and fcntl to set flags. less syscalls is a good thing as syscalls are not cheap on some architectures or systems. I've seen a syscall on 1 system take 2-3x as long as another and another syscall in the same 2 system comparison take 10x as long. depending on the syscall you may only have a budget of something like 5000 syscalls "per frame" (60fps) before you spend all of your frame time just in syscalls not doing any processing, so we should keep these down if possible and that is what this does. --- header_checks/meson.build | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'header_checks') diff --git a/header_checks/meson.build b/header_checks/meson.build index ff5b21ee0c..4cc855e218 100644 --- a/header_checks/meson.build +++ b/header_checks/meson.build @@ -123,6 +123,20 @@ function_checks = [ ['dladdr', ['dlfcn.h'], ['dl'], '-D_GNU_SOURCE=1'] ] +open_cloexec = cc.run('''#include + #include + #include + int main(int argc, char **argv) { + int res = open(argv[0], O_RDONLY | O_CLOEXEC); + if (res < 0) return 1; + return 0; + } + ''', + name : 'open works with O_CLOEXEC') +if open_cloexec.compiled() and open_cloexec.returncode() == 0 + config_h.set10('HAVE_OPEN_CLOEXEC', true) +endif + strerror_r_char_p = cc.compiles('''#define _GNU_SOURCE #include int func (void) -- cgit v1.2.1