Multi Core Processors

[owaisulhaq]

Respected Members,

I have a doubt regarding multi core processors (like i3, i5 and i7) that do they utilize all of their cores in all softwares to speed up the job ?
As many softwares dont have any option of using multi cores. So when we run such softwares do other cores remain unused at that time or the system itself distributes load among its all cores ?
Thirdly if this is the case then for such application wont it be better to use "3.2 GHz Pentium4" rather than a "2.13 GHz Core i3" if the system doesnot ?
Last question if I am using Windows 7 or Windows XP then automatically load is being distributed or not among the cores ?

Thanks

 

[GammaLaser]

Hi and welcome to the forums!

Respected Members,

I have a doubt regarding multi core processors (like i3, i5 and i7) that do they utilize all of their cores in all softwares to speed up the job ?

No, as you mention if the software is not designed for multi-core then it will not use all of the available cores in the CPU.

As many softwares dont have any option of using multi cores. So when we run such softwares do other cores remain unused at that time or the system itself distributes load among its all cores ?

The other cores will be unused at a given instant. However, the OS may decide to schedule a program on a different core on a context switch (which can happen many times a second). So in Windows if you look at Task Manager it may look like multiple cores are being used on average, but the total CPU usage is still as if one core is being used.

Thirdly if this is the case then for such application wont it be better to use "3.2 GHz Pentium4" rather than a "2.13 GHz Core i3" if the system doesnot ?

No, the frequency alone does not dictate the single-threaded performance of the CPU. The per-core performance is roughly given by frequency * instructions per cycle. Even though the Pentium4 is higher frequency, the Core i3 has an even higher instructions per cycle so that overall the Core i3 is probably much faster even in programs that are not multi-threaded.

Last question if I am using Windows 7 or Windows XP then automatically load is being distributed or not among the cores ?

Thanks

Yes, Windows will automatically take care of scheduling multithreaded programs across the cores. However Windows 7 tends to do a better job at this.

 

[Tuna-Fish]

Thirdly if this is the case then for such application wont it be better to use "3.2 GHz Pentium4" rather than a "2.13 GHz Core i3" if the system doesnot ?

This is a comparison between a 3.2GHz P4 and a 2.93 GHz i3. While most of the tests are multithreaded to some extent, pay attention to the Cinebench R10 (Single Threaded) test.

http://www.anandtech.com/bench/Product/92?vs=118

The speed of a core depends not only on the clockspeed, but also on it's instructions per clock. The P4 design pushed for higher clockspeed at all costs -- and this approach resulted in horribly inefficient execution. A Pentium 4 does less work per clock than a Pentium 3, only being able to beat it because it clocks so much higher, and at the end of their era, AMD K8 cpus operating at two-thirds their clockspeed could go toe-to-toe with the P4.

Modern designs like the i3 330 do more than twice the work per clock than p4 did.

 

[owaisulhaq]

Thanks Members for your comprehensive and helpful answers

I also want to ask if we have a PC and a laptop having exactly same specifications (same motherboard, Processor, RAM, OS), Will their performance will be exactly same or laptop will be on a slightly slower side a bit ? (I have heard that laptop will be on slower side practically) ?

 

[owaisulhaq]

Sir,
tell me that if I am running like 3 heavy (but not multithreaded) programs on my Core i3 processor. My Windows 7 will distribute one program to each core (and such utilize 3 cores) or put all the load on first core and only use other cores when needed and load is out of control for first core.
I will like to thank you for bearing my stupid questions. Thanks alot

 

[janas19]

Sir,
tell me that if I am running like 3 heavy (but not multithreaded) programs on my Core i3 processor. My Windows 7 will distribute one program to each core (and such utilize 3 cores) or put all the load on first core and only use other cores when needed and load is out of control for first core.
I will like to thank you for bearing my stupid questions. Thanks alot

No, what the Windows scheduler does is allocate the resources (cores) based on the applications demands. If an application requests a core and it is free, the scheduler will use that free core until the process/instruction is completed, and so on.

So for example, if you have 3 applications open, and all 3 send a request to the CPU, the scheduler will allocate those requests to the separate available cores.

 

[mindless1]

This is not a highly technical question. Newer CPUs and newer software is desirable because they are optimized for more performance. Research the software before you buy it to find out if it leverages performance gains from multi-core CPUs or certain architectures or instruction sets, but frankly in most cases where these things matter you end up picking the most popular industry standard software instead, or at least the one that fits within the budget.