From 65b338ad04e2c1943d039ed6e31f43f0aaa5db4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <filmroellchen@serenityos.org>
Date: Fri, 4 Mar 2022 14:57:38 +0100
Subject: [PATCH] AK: Allow alignment to cache line size with CACHE_ALIGNED

This is particularly important to avoid false sharing, which thrashes
performance when two process-shared atomics are on the same cache line.
---
 AK/Platform.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/AK/Platform.h b/AK/Platform.h
index d69ceba3af..b1534436d5 100644
--- a/AK/Platform.h
+++ b/AK/Platform.h
@@ -110,3 +110,16 @@ extern "C" {
 #    define CLOCK_MONOTONIC_COARSE CLOCK_MONOTONIC
 #    define CLOCK_REALTIME_COARSE CLOCK_REALTIME
 #endif
+
+#ifndef SYSTEM_CACHE_ALIGNMENT_SIZE
+#    if ARCH(AARCH64) || ARCH(x86_64)
+#        define SYSTEM_CACHE_ALIGNMENT_SIZE 64
+#    else
+#        define SYSTEM_CACHE_ALIGNMENT_SIZE 128
+#    endif
+#endif /* SYSTEM_CACHE_ALIGNMENT_SIZE */
+
+#ifdef CACHE_ALIGNED
+#    undef CACHE_ALIGNED
+#endif
+#define CACHE_ALIGNED alignas(SYSTEM_CACHE_ALIGNMENT_SIZE)