X-bit labs

AMD Athlon 64 X2 4800+ Dual-Core Processor Review (page 16)

Category: CPU

by Ilya Gavrichenkov

[ 05/08/2005 | 09:11 PM ]

General Impressions

Before we voice our verdict about the dual-core newcomer from AMD, we would like to say a few words about the things, which we haven’t yet touched upon. I am talking about the comfort of using a computer system equipped with a dual-core processor. The thing is that if there is one single-core CPU in your system, such as Athlon 64, for example, there is only one computational thread processed at a given moment of time. It means that if there a few applications running on this system at the same time, the OS scheduler will have to switch the resources between the tasks at higher frequency.

Since contemporary CPUs are very fast, the user hardly ever notices this switch. However, there are certain applications, which cannot be interrupted that easily, so that the processor time could be given to other tasks in the queue. In this case the OS will experience delays, which may be quite irritating for the user. Also, you can sometimes see the application freeze after the CPU resources have already been taken, and in this case the application is really hard to end, because it wouldn’t return the resources even to the OS scheduler.

Problems like that can occur in systems with dual-core CPUs over 10 times as rarely. The thing is that CPUs with two physical cores can process two computational threads at a time, which frees twice as many resources for the scheduler to distribute between the working applications. In fact, there should be two processes trying to get all CPU resources simultaneously for the system with a dual-core CPU to become uncomfortable to work on.

In conclusion we decided to undertake a small experiment showing how the simultaneous processing of multiple resource-hungry applications can affect the performance of systems with a single- and dual-core CPU. For this purpose we measured the fps rate in Half-Life 2 running with a few copies of WinRAR archiving utility in the background.

As we see, with Athlon 64 X2 4800+ CPU in the system the performance in Half-Life 2 remains acceptable for a much longer period of time than in case we have an Athlon 64 FX-55, even though the latter worked at higher clock rate. In fact, even if there is only one application running in the background on your single-core processor based system, the performance will get two times lower. The more background tasks you’ve got, the greater is the performance drop.

If there is a dual-core CPU in the system, you can maintain acceptable performance level in the primary application for a much longer period of time. One WinRAR copy running in the background remains almost unnoticed, and if there are more applications added to it, the influence on the performance in the primary task will be noticeable, but will not be that dramatic at all. Note that in this case the performance will drop mostly not because of the lack of processor resources, but because of the memory bus bandwidth limitations, as it has to be shared between all those applications, in other words, if the tasks in the background do not need to work with the memory that much, then the performance of the primary application will hardly be affected at all by the growing background workload.