The CPU performance race in the computer processor field can only be won by manufacturers who focus on a reasonable balance of clock speed and processing units, based on the existing manufacturing technology. With availability of 90 nm, 65 nm and 45 nm manufacturing processes, processors with more than one unit became possible thanks to manageable heat dissipation and die sizes, and we're looking at more and more quad core processors today. But how does current software really scale from single to dual and quad cores? In an ideal world, thread-optimized software allows the operating system to distribute multiple threads across the available processing units, whether these are found on a single processor or multiple processors with a single or multiple cores. Adding more cores can unleash much more performance than any clock speed increase.

This makes sense: obviously, more workers are almost always faster than fewer faster workers. But, it can also be very tricky to distribute the workloads to the workers, especially when the application was written before multi core processors ever seen the light of this world. Single thread applications (which most Audio applications are so far) would utilize one CPU core fully and the others would be just be waiting around for another instance or program to be run. That way most of the Studio applications would benefit from fewer cores with higher clock speed.

Single core CPU running at 3.4 GHZ for $100 will outperform $1000 quad core where each of the cores run at 2.4 GHZ. That reminds me of a situation when I drive from work and get stuck in traffic because there is a construction or maintenance going on, when you finally get to the point where the construction is, there is one guy frantically swinging his pickaxe in the hole and three others are watching him leaning on their shovels.

In this article, we'll have a look at a Core 2 Duo configuration running a quad core, a dual core and a single core CPUs, and compare how the extra cores scale. Is it worth going for a quad core today?

What is a single core: The term "single core" applies to a processor that has a single processing unit. This applies to virtually every CPU from the early 8086 up to the Athlon 64 and Intel Pentium 4. Until manufacturing processes became sophisticated enough to allow the design of microchips with two processing units on a die, smaller structures were used to reduce the operating voltage, lowering heat generation and increase the clock speed or introduce more functional units and cache memory. Driving a single core processor to high clock speeds may deliver high performance for a single application, but the processor can only work on one task (thread) at a time.

What is a dual core: Having two processing cores means having theoretically twice the processing power, but only if your applications are really thread-optimized. Unfortunately professional audio software engineers and developers are taking their time to rewrite their software packages for multithread support so it could utilize several CPU cores. Everybody is afraid that it would bring a whole another world of problems, incompatibility and bugs which would take some time to fix and resolve. And audio engineers hate bugs ! Every problem related to your Digital Audio Workstation will kill creativity, costs time and turn everything in an aggravating task. On the other hand a dual core processor still makes a lot of sense even if you only use your computer to write email, browse the Web and work on office files such as documents or spreadsheets at the same time. The current models do not require noticeably more energy than single core models, the second processing core not only gives you more performance, it maximizes system responsiveness while switching between programs.

What is a Quad Core: The Quad core concepts put four cores and their cache memory onto a single die. The important thing is to have a shared, unified cache. Which will improve communication among the cores, AMD introduces the 512 kB L2 cache for each core, and adding a L3 cache to all cores. Also another advantage is that it will be possible to shut down individual cores and accelerate others in order to achieve better single-thread performance. Intel will follow the same path, but not before the introduction of its 2008 Nehalem architecture.

But let's not jump too far ahead. While there are many reasons to opt for a dual core processor, the quad cores do not yet always live up to their full potential, because of limited thread-optimizations of available professional software. The future is clearly in multi core processing, that's why we should have an Octocore available by 2010.

As a testing reference there is the Audeum AS-O2 Custom Digital Audio Workstation with fully audio optimized Microsoft Windows XP. Used reference, quotes and testing tool from Tom's hardware. Professional environment at Front End Audio studio lab. All CPUs ( Single Core, Dual Core & Quadcore ) were clocked at 2.4 GHZ.

Results : Our benchmarks show that there is very little or no improvement in high end graphic and multimedia playback between dual and quad core. There is about 10% increase between single and dual core CPUs due to better responsiveness of the system with multi core. There was literally 0% increase in performance using a Quad core CPU versus a Dual core CPU.

Different story is in professional editing software that supports multi core CPUs like 3D Studio MAX, rendering of a single frame in high resolution took almost 3 times longer to process on Single core than on a quad core equipped system and about half the time to a Dual core CPU.

Video transcoding test (MPEQ2 to H.264) shows that our reference file was processed in 7 minutes on a Quad Core CPU, 10 minutes on A Dual core CPU and 19 Minutes on a Single core CPU.

CD audio to MP3 Conversion test had the exact results across all CPUs showing that there is no difference in performance using Single, Dual or Quad core CPU.

Overall system test using SYSMARK 2007 showed us that there is about 30% increase in performance using Dual core CPU versus Single core and about 1% increase for Quad core CPU over Dual core CPU.

PCMmark 05 test revealed that there is no difference affecting the memory performance using Single, Dual or Quad CPU.

In File compression test supporting Multi Core CPUs we found out that our file took 86 seconds to be processed on a Single core CPU, 61 seconds on Dual Core and about 4 seconds less on Quad core CPU.

DivX video transcoding from Mpeg-2 to Mpeg-4 showed that we saved 12 seconds using Dual Core CPU versus Single Core and an additional 1 second using Quad Core CPU.

Conclusion : As we see, there are considerable performance differences between a Core 2 processor running on one, two or four cores. Professional applications such as the graphics rendering suite 3DStudio Max, Cinebench or Mainconcept's H.264 encoder require as much performance as they can get, and hence were already optimized to make maximum use of dual and quad core processors. All three scale almost linearly, and are close to doubling performance when doubling the core count. Audio and video transcoding benchmarks clearly benefit from a second core, but not yet from four cores.

Overall, the current quad core processor generation does provide the performance reserves that Intel promised. However, there are still many applications that do not yet take much advantage of two or more cores. Our conclusion is thus simple: Since there is a pressure applied by CPU manufacturers to discontinue popular and well performing CPUs running at high clock speeds for a bargain price, the next available is a high clock Dual Core CPU. That way our single thread audio applications will run fast and smooth with benefit of possibility engaging another core to help out with the task when the time is right and update or multi thread version of our recording software will be available. My suggestion is to stick to a reasonably priced Dual Core CPU.

Ladia Svajcik Senior Systems Engineer MCSE, MCSA, MCP, CompTIA Security+ www.audeum.com