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authorStefano Brivio <sbrivio@redhat.com>2022-02-28 16:18:44 +0100
committerStefano Brivio <sbrivio@redhat.com>2022-02-28 16:46:28 +0100
commit213c397492bdc64cf26b2e7b3877e4a29dc9f8da (patch)
tree50f69783c009918e6a1ef5a22b2d7d88407488e2 /arch.c
parentdeca1ebe5093affd581a27855180821a8b6b3079 (diff)
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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 <sbrivio@redhat.com>
Diffstat (limited to 'arch.c')
-rw-r--r--arch.c42
1 files changed, 42 insertions, 0 deletions
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 <sbrivio@redhat.com>
+ */
+
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+/**
+ * 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