Leniel Maccaferri's blog: November 2009

During my childhood I used to play video games. I started playing the Atari in my older cousins’ house in 1989-1990 when I was 6 to 7 years old, and then my uncle gave me a Phantom System in 1992. For some time I played a Master System in 1994/1995?. While in the house of my neighbor I played the Mega Drive. My newer cousins also had videogames and I used to play with them the Super Nintendo in 1996 and after that the Nintendo 64 bits in 1997.

My parents gave me a computer ( oh, a computer… how I wanted it! ) in 1997 and of course I played games on the computer. I kept playing games on the computer for a long time. It was only after I started the computer engineering graduation in 2003 that I definitely stopped playing games. What’s the reason for that? I also would like to know. : )

A hiatus of 6-7 years till I write this post.

Firstly I’ve decided to buy a video game console because I think it’s a excellent way to relax and one of the best pastimes. After all a computer engineer/software developer needs some fun too!
Secondly, I love technology and I get mesmerized by the evolution the videogame industry brings to our life and our eyes. Video games simulate the real world and help us understand the environment in which the game is built upon.
Last but not least because today I can afford a video game console.

How can those guys develop such things? Wow, that’s what I thought when I started playing again.

I chose the PlayStation 3 (PS3) platform having in mind its great graphics. There’s no limit to innovation when it comes to computer graphics and PS3 shows us just that.

On November 19 I bought the new PS3 slim model - 120 GB. To pair with it I also bought the so acclaimed game Call of Duty - Modern Warfare 2 also known as COD - MW2.

PlayStation 3 slim model

The combination of PS3 with COD MW 2 is fantastic. You pass exciting moments in front of the TV.

In just 3 days I completed all the single player missions in the recruiter profile. The only part that I didn’t like in the game: the single player campaign is too short! Despite that you get what you pay for, that is, great graphics, great playability and great sensations.

I have a wireless home network and the PS3 has wireless support. The wireless router is in my bedroom and the PS3 is in the living room. The network setup is really straightforward. After configuring your network you can connect to the PlayStation Store to download demos, see movies, read news about the gaming world and of course play online against fellow gamers (not AI) in multiplayer mode.

Below you can see my portable Id in the PlayStation Network also known as the PSN Network.

Other great feature PS3 has is the support to playback Blu-ray video.

That’s it. I’m back to the gaming world.

Feel free to invite me to your PSN friends list. It’s always good to play online. My PSN name is johnleniel.

I really recommend to anyone who can afford it to buy a modern seventh generation video game console. You won’t be disappointed. You’ll have a lot of fun. :- )

On the last day of May I wrote about how to calculate prime numbers with LINQ in C#. To close that post I said that I’d use the PrimeNumbers delegate to evaluate PLINQ (Parallel LINQ) and measure the performance gains when the same calculation is done in parallel instead of in a sequential fashion.

PLINQ is LINQ executed in Parallel, that is, using as much processing power as you have in your current computer.

If you have a computer with 2 processor cores like a dual core processor you'll get your Language Integrated Query operators do the work in parallel using both cores.

Using "only" LINQ you won't get as much performance because the standard Language Integrated Query operators won't parallelize your code. That means your code will run in a serial fashion not taking advantage of all your available processor cores.

There are lots of PLINQ query operators capable of executing your code using well known parallel patterns.

After this brief introduction to PLINQ let’s get to the code.

As promised, today I show the performance gains when the PrimeNumbers delegate is run in 2 cores (parallel) instead of only 1 core (sequential).

Here’s the delegate code:

Func<int, IEnumerable<int>> PrimeNumbers = max =>
from i in Enumerable.Range(2, max - 1)
where Enumerable.Range(2, i - 2).All(j => i % j != 0)
select i;

To make it a candidate to parallelization we must just call the AsParallel() extension method on the data to enable parallelization for the query:

Func<int, IEnumerable<int>> PrimeNumbers = max =>
from i in Enumerable.Range(2, max - 1).AsParallel()
where Enumerable.Range(2, i - 2).All(j => i % j != 0)
select i;

I set up a simple test to measure the time elapsed when using the two possible ways of calling the delegate function, that is, sequentially in one core and parallelized in my two available cores (I have an Intel Pentium Dual Core E2180 @ 2.00 GHz / 2.00 GHz).

Let’s calculate the prime numbers that are less than 50000 sequentially and in parallel:

IEnumerable<int> result = PrimeNumbers(50000);

Stopwatch  stopWatch = new Stopwatch();

stopWatch.Start();

foreach(int i in result)
{
    Console.WriteLine(i);
}

stopWatch.Stop();

// Write time elapsed
Console.WriteLine("Time elapsed: {0}", stopWatch.Elapsed);

Now the results:

1 core
Time elapsed: 00:00:06.0252929

2 cores
Time elapsed: 00:00:03.2988351

8 cores*
Time elapsed: 00:00:00.8143775

* read the Update addendum bellow

When running in parallel using the #2 cores, the result was great - almost half the time it took to run the app in a sequential fashion, that is, in only #1 core.

The whole work gets divided into two worker threads/tasks as shown in Figure 1:

Prime Numbers PLINQ Parallel Stacks Window ( #2 cores )
Figure 1 - The Parallel Stacks window in Visual Studio 2010 ( #2 cores )

You can see that each thread is responsible for a range of values (data is partitioned among available cores). Thread 1 is evaluating the value 32983 and Thread 3 is evaluating 33073. This all occurs synchronously.

If I had a computer with 4 cores, the work would be divided into 4 threads/tasks and so on. If the time kept decreasing I’d achieve 1.5 seconds to run the app. Fantastic, isn’t it?

The new Microsoft Visual Studio 2010 (currently in Beta 2) comes with great debugging tooling for parallel applications as for example the Parallel Stacks shown in Figure 1 and the Parallel Tasks window shown in Figure 2:

Prime Numbers PLINQ Parallel Tasks Window ( #2 cores )
Figure 2 - The Parallel Tasks window in Visual Studio 2010 ( #2 cores )

This post gives you a rapid view of PLINQ and how it can leverage the power of you current and future hardware.

The future as foreseen by hardware industry specialists is a multicore future. So why not get ready to it right now? You certainly can with PLINQ. It abstracts all the low level code to get parallel and let’s you focus on what’s important: your business domain.

If you want to go deep using PLINQ, I advise you to read Patterns for Parallel Programming: Understanding and Applying Parallel Patterns with the .NET Framework 4 by Stephen Toub.

Updated on February 15, 2013

Running this same sample app on a Intel Core i7-3720QM 2.6GHz quad-core processor (with #4 cores and #8 threads) this is the result:

Time elapsed: 00:00:00.8143775

This is on a par with the #1 core and #2 cores tests shown above. The work is being divided "almost" evenly by 8 if we compare with the first benchmark ( only #1 core ).

00:00:06.0252929 / 8 = 0.7525

Of course there’s been lots of improvements between these different processor generations. The software algorithms used to parallelize the work have also been improved (now I’m running on Visual Studio 2012 with .NET 4.5). Both hardware/software specs are higher now. Nonetheless these numbers give a good insight about the performance gains both in terms of hardware and software. Software developers like me have many reasons to celebrate! Party smile