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C# FalseSharingEffects
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConcurrencyExamples
{
class FalseSharingDemo
{
public readonly static int NUM_THREADS = 8; // change
public readonly static int ITERATIONS = 500 * 1000 * 1000;
public static void Main(string[] args)
{
var sw = Stopwatch.StartNew();
runTest();
sw.Stop();
Console.WriteLine("duration = {0} ticks, {1}s", sw.ElapsedTicks, sw.Elapsed.Seconds);
Console.ReadKey();
}
private static void runTest()
{
Thread[] threads = new Thread[NUM_THREADS];
for (int i = 0; i < threads.Length; i++)
{
threads[i] = new Thread(new FalseSharing(i).run);
}
foreach (Thread t in threads)
{
t.Start();
}
foreach (Thread t in threads)
{
t.Join();
}
}
}
class FalseSharing
{
private readonly int arrayIndex;
private static VolatileValue[] longs = new VolatileValue[FalseSharingDemo.NUM_THREADS];
static FalseSharing()
{
for (int i = 0; i < longs.Length; i++)
{
longs[i] = new VolatileValue();
}
}
public FalseSharing(int arrayIndex)
{
this.arrayIndex = arrayIndex;
}
public void run()
{
int i = FalseSharingDemo.ITERATIONS + 1;
while (0 != --i)
{
longs[arrayIndex].value = i;
}
}
}
class VolatileValue
{
public volatile int value; //4 byte
//int[] padding = new int[15]; //padding with (4 * 15) = 60 bytes to align the object to the 64 byte cacheline size
//long p0, p1, p2, p3, p4, p5, p6; int p8; // manual padding with 7 * 8 bytes =56 byte + 4 byte = 60 byte // could this be optimzed away -> unused?!
}
}
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConcurrencyExamples
{
class FalseSharingDemo
{
public readonly static int NUM_THREADS = 8; // change
public readonly static int ITERATIONS = 500 * 1000 * 1000;
public static void Main(string[] args)
{
var sw = Stopwatch.StartNew();
runTest();
sw.Stop();
Console.WriteLine("duration = {0} ticks, {1}s", sw.ElapsedTicks, sw.Elapsed.Seconds);
Console.ReadKey();
}
private static void runTest()
{
Thread[] threads = new Thread[NUM_THREADS];
Enumerable.Range(0, threads.Length).Select((i) => threads[i] = new Thread(new FalseSharing(i).run)).ToList();
Array.ForEach(threads, t => t.Start());
Array.ForEach(threads, t => t.Join());
}
}
class FalseSharing
{
private readonly int arrayIndex;
private static VolatileValue[] longs = new VolatileValue[FalseSharingDemo.NUM_THREADS];
static FalseSharing()
{
for (int i = 0; i < longs.Length; i++)
{
longs[i] = new VolatileValue();
}
}
public FalseSharing(int arrayIndex)
{
this.arrayIndex = arrayIndex;
}
public void run()
{
int i = FalseSharingDemo.ITERATIONS + 1;
while (0 != --i)
{
longs[arrayIndex].value = i;
}
}
}
class VolatileValue
{
public volatile int value; //4 byte
//long p0, p1, p2, p3, p4, p5, p6; int p8; // manual padding with 7 * 8 bytes =56 byte + 4 byte = 60 byte // could this be optimzed away -> unused?!
}
}
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConcurrencyExamples
{
class FalseSharingDemo
{
public readonly static int NUM_THREADS = 8; // change
public readonly static int ITERATIONS = 500 * 1000 * 1000;
private static void runTest()
{
VolatileValue[] values = new VolatileValue[FalseSharingDemo.NUM_THREADS];
Parallel.For(0, NUM_THREADS, threadIndex =>
{
values[threadIndex] = new VolatileValue();
int counter = FalseSharingDemo.ITERATIONS + 1;
while (counter-- >= 0)
{
values[threadIndex].value = counter;
}
});
}
public static void Main(string[] args)
{
var sw = Stopwatch.StartNew();
runTest();
sw.Stop();
Console.WriteLine("duration = {0} ticks, {1}s", sw.ElapsedTicks, sw.Elapsed.Seconds);
Console.ReadKey();
}
}
class VolatileValue
{
public volatile int value; //4 byte
long p0, p1, p2, p3, p4, p5, p6; int p8; // manual padding with 7 * 8 bytes =56 byte + 4 byte = 60 byte // could this be optimzed away -> unused?!
}
}
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