From 36bc90b474969707a30a6bbdcf38b4d5a2271a72 Mon Sep 17 00:00:00 2001
From: David Cantu <dacantu@microsoft.com>
Date: Wed, 14 Apr 2021 23:30:20 -0700
Subject: [PATCH 1/2] Add WriteAllBytes benchamarks

---
 .../System.IO.FileSystem/Perf.File.cs         | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs b/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
index f1430ee8535..41ce13a102a 100644
--- a/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
+++ b/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
@@ -2,8 +2,11 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Extensions;
 using MicroBenchmarks;
 
 namespace System.IO.Tests
@@ -11,10 +14,18 @@ namespace System.IO.Tests
     [BenchmarkCategory(Categories.Libraries)]
     public class Perf_File
     {
+        private const int OneKibibyte = 1 << 10; // 1024
+        private const int HalfKibibyte = OneKibibyte >> 1;
+        private const int FourKibibytes = OneKibibyte << 2; // default Stream buffer size
+        private const int SixteenKibibytes = FourKibibytes << 2; // default Stream buffer size * 4
+        private const int OneMibibyte = OneKibibyte << 10;
+        private const int HundredMibibytes = OneMibibyte * 100;
+
         private const int DeleteteInnerIterations = 10;
         
         private string _testFilePath;
         private string[] _filesToRemove;
+        private Dictionary<int, byte[]> _userBuffers;
 
         [GlobalSetup(Target = nameof(Exists))]
         public void SetupExists()
@@ -46,5 +57,40 @@ public void Delete()
             foreach (var file in filesToRemove)
                 File.Delete(file);
         }
+
+        [GlobalSetup(Targets = new[] { nameof(WriteAllBytes), "WriteAllBytesAsync" })]
+        public void SetupWriteAllBytes()
+        {
+            _testFilePath = FileUtils.GetTestFilePath();
+            _userBuffers = new Dictionary<int, byte[]>()
+            {
+                { HalfKibibyte, ValuesGenerator.Array<byte>(HalfKibibyte) },
+                { FourKibibytes, ValuesGenerator.Array<byte>(FourKibibytes) },
+                { SixteenKibibytes, ValuesGenerator.Array<byte>(SixteenKibibytes) },
+                { OneMibibyte, ValuesGenerator.Array<byte>(OneMibibyte) },
+                { HundredMibibytes, ValuesGenerator.Array<byte>(HundredMibibytes) },
+            };
+        }
+
+        [Benchmark]
+        [Arguments(HalfKibibyte)]
+        [Arguments(FourKibibytes)]
+        [Arguments(SixteenKibibytes)]
+        [Arguments(OneMibibyte)]
+        [Arguments(HundredMibibytes)]
+        public void WriteAllBytes(int userBuffer) => File.WriteAllBytes(_testFilePath, _userBuffers[userBuffer]);
+
+#if !NETFRAMEWORK
+        [Benchmark]
+        [Arguments(HalfKibibyte)]
+        [Arguments(FourKibibytes)]
+        [Arguments(SixteenKibibytes)]
+        [Arguments(OneMibibyte)]
+        [Arguments(HundredMibibytes)]
+        public Task WriteAllBytesAsync(int userBuffer) => File.WriteAllBytesAsync(_testFilePath, _userBuffers[userBuffer]);
+#endif
+
+        [GlobalCleanup(Targets = new[] { nameof(WriteAllBytes), "WriteAllBytesAsync" })]
+        public void CleanupWriteAllBytes() => File.Delete(_testFilePath);
     }
 }

From f842a8506464750c7c3fea3263e9681f53e00bc5 Mon Sep 17 00:00:00 2001
From: Adam Sitnik <adam.sitnik@gmail.com>
Date: Thu, 15 Apr 2021 14:39:22 +0200
Subject: [PATCH 2/2] Apply suggestions from code review

---
 .../micro/libraries/System.IO.FileSystem/Perf.File.cs         | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs b/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
index 41ce13a102a..631903b8f2f 100644
--- a/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
+++ b/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
@@ -78,7 +78,7 @@ public void SetupWriteAllBytes()
         [Arguments(SixteenKibibytes)]
         [Arguments(OneMibibyte)]
         [Arguments(HundredMibibytes)]
-        public void WriteAllBytes(int userBuffer) => File.WriteAllBytes(_testFilePath, _userBuffers[userBuffer]);
+        public void WriteAllBytes(int size) => File.WriteAllBytes(_testFilePath, _userBuffers[size]);
 
 #if !NETFRAMEWORK
         [Benchmark]
@@ -87,7 +87,7 @@ public void SetupWriteAllBytes()
         [Arguments(SixteenKibibytes)]
         [Arguments(OneMibibyte)]
         [Arguments(HundredMibibytes)]
-        public Task WriteAllBytesAsync(int userBuffer) => File.WriteAllBytesAsync(_testFilePath, _userBuffers[userBuffer]);
+        public Task WriteAllBytesAsync(int size) => File.WriteAllBytesAsync(_testFilePath, _userBuffers[size]);
 #endif
 
         [GlobalCleanup(Targets = new[] { nameof(WriteAllBytes), "WriteAllBytesAsync" })]