From 213c397492bdc64cf26b2e7b3877e4a29dc9f8da Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Mon, 28 Feb 2022 16:18:44 +0100 Subject: passt, pasta: Run-time selection of AVX2 build Build-time selection of AVX2 flags and routines is not practical for distributions, but limiting AVX2 usage to checksum routines with specific run-time detection doesn't allow for easy performance gains from auto-vectorisation of batched packet handling routines. For x86_64, build non-AVX2 and AVX2 binaries, and implement a simple wrapper replacing the current executable with the AVX2 build if it's available, and if AVX2 is supported by the current CPU. Signed-off-by: Stefano Brivio --- arch.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 arch.c (limited to 'arch.c') diff --git a/arch.c b/arch.c new file mode 100644 index 0000000..b8e1db5 --- /dev/null +++ b/arch.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: AGPL-3.0-or-later + +/* PASST - Plug A Simple Socket Transport + * for qemu/UNIX domain socket mode + * + * PASTA - Pack A Subtle Tap Abstraction + * for network namespace/tap device mode + * + * arch.c - Architecture-specific implementations + * + * Copyright (c) 2022 Red Hat GmbH + * Author: Stefano Brivio + */ + +#include +#include +#include +#include + +/** + * arch_avx2_exec() - Run AVX2 build if supported, drop suffix from argv[0] + * @argv: Arguments from command line + */ +#ifdef __x86_64__ +void arch_avx2_exec(char **argv) +{ + char *p = strstr(argv[0], ".avx2"); + + if (p) { + *p = 0; + } else if (__builtin_cpu_supports("avx2")) { + char path[PATH_MAX]; + + snprintf(path, PATH_MAX, "%s.avx2", argv[0]); + argv[0] = path; + execve(path, argv, environ); + perror("Can't run AVX2 build, using non-AVX2 version"); + } +} +#else +void arch_avx2_exec(char **argv) { (void)argv; } +#endif -- cgit v1.2.3