From 807febcb5edb9fe7f6dbd9a6430c9034ec22e592 Mon Sep 17 00:00:00 2001
From: Jacob Sandlund <jacob@jacobsandlund.com>
Date: Tue, 25 Nov 2025 09:07:21 -0500
Subject: [PATCH] benchmarks: align read_buf to cache line

---
 src/benchmark/CodepointWidth.zig | 6 +++---
 src/benchmark/GraphemeBreak.zig  | 4 ++--
 src/benchmark/IsSymbol.zig       | 4 ++--
 src/benchmark/ScreenClone.zig    | 2 +-
 src/benchmark/TerminalParser.zig | 2 +-
 src/benchmark/TerminalStream.zig | 2 +-
 6 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/benchmark/CodepointWidth.zig b/src/benchmark/CodepointWidth.zig
index 552df8d1f..effabb036 100644
--- a/src/benchmark/CodepointWidth.zig
+++ b/src/benchmark/CodepointWidth.zig
@@ -107,7 +107,7 @@ fn stepWcwidth(ptr: *anyopaque) Benchmark.Error!void {
     const self: *CodepointWidth = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
@@ -134,7 +134,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
     const self: *CodepointWidth = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
@@ -166,7 +166,7 @@ fn stepSimd(ptr: *anyopaque) Benchmark.Error!void {
     const self: *CodepointWidth = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
diff --git a/src/benchmark/GraphemeBreak.zig b/src/benchmark/GraphemeBreak.zig
index a1b3380f0..328d63a75 100644
--- a/src/benchmark/GraphemeBreak.zig
+++ b/src/benchmark/GraphemeBreak.zig
@@ -90,7 +90,7 @@ fn stepNoop(ptr: *anyopaque) Benchmark.Error!void {
     const self: *GraphemeBreak = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
@@ -113,7 +113,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
     const self: *GraphemeBreak = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
diff --git a/src/benchmark/IsSymbol.zig b/src/benchmark/IsSymbol.zig
index c4667b333..5ba2da907 100644
--- a/src/benchmark/IsSymbol.zig
+++ b/src/benchmark/IsSymbol.zig
@@ -90,7 +90,7 @@ fn stepUucode(ptr: *anyopaque) Benchmark.Error!void {
     const self: *IsSymbol = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
@@ -117,7 +117,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
     const self: *IsSymbol = @ptrCast(@alignCast(ptr));
 
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
diff --git a/src/benchmark/ScreenClone.zig b/src/benchmark/ScreenClone.zig
index 7225aff4e..380379bc3 100644
--- a/src/benchmark/ScreenClone.zig
+++ b/src/benchmark/ScreenClone.zig
@@ -109,7 +109,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
     var stream = self.terminal.vtStream();
     defer stream.deinit();
 
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = data_f.reader(&read_buf);
     const r = &f_reader.interface;
 
diff --git a/src/benchmark/TerminalParser.zig b/src/benchmark/TerminalParser.zig
index f13b44552..e00081763 100644
--- a/src/benchmark/TerminalParser.zig
+++ b/src/benchmark/TerminalParser.zig
@@ -75,7 +75,7 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
     // the benchmark results and... I know writing this that we
     // aren't currently IO bound.
     const f = self.data_f orelse return;
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     var r = &f_reader.interface;
 
diff --git a/src/benchmark/TerminalStream.zig b/src/benchmark/TerminalStream.zig
index 0a993c42b..7cf28217f 100644
--- a/src/benchmark/TerminalStream.zig
+++ b/src/benchmark/TerminalStream.zig
@@ -114,7 +114,7 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
     // aren't currently IO bound.
     const f = self.data_f orelse return;
 
-    var read_buf: [4096]u8 = undefined;
+    var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     var f_reader = f.reader(&read_buf);
     const r = &f_reader.interface;