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Gumby
Fishnologist


Registered: 06/13/01
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Can someone explain processors to me?
#8127461 - 03/10/08 01:20 PM (16 years, 2 months ago) |
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So companies are coming out with multiple core processors. Like dual core or quad core... What exactly is a core?
I remember reading on here (I think) that most programmers don't program/know how to program for multiple cores. Why is that? Is it just really difficult? What type of programs usually do take advantage of all cores?
I ask because I have a 3.4Ghz Pentium 4 dual-core (Northwood) processor. Right now I'm converting an AVI to DVD format. When I pull up task manager, it says only 50% of my resources are being used. Does that mean it's only using one core? If the software was capable of using 100% of my resources would the conversion go faster? Basically: am I getting all the power out of my CPU that I should/could be getting?
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slackophage
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Registered: 11/16/06
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Re: Can someone explain processors to me? [Re: Gumby]
#8127511 - 03/10/08 01:35 PM (16 years, 2 months ago) |
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It has to do with the program being able to spawn multiple threads. This means the program will split into two or more copies of itself and each copy will go do it's own thing, usually on different CPUs (or cores, or virtual cores if you're using hyperthreading). This makes the programs harder to write since you have to account for the program splitting up the work, and possibly reporting the results back to the master thread.
A good example is a media player I once used called Xine. It would spawn a thread for decoding video, and another for decoding audio. I think Mplayer does it this way too.
Sounds like your encoding app doesn't do this, one that handles threading properly could be up to twice as fast.
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Gumby
Fishnologist


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Re: Can someone explain processors to me? [Re: slackophage]
#8127558 - 03/10/08 01:47 PM (16 years, 2 months ago) |
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I know my processor has hyperthreading... So what exactly is hyperthreading? The wikipedia article is gibberish to me.
Also, anyone know of any video format conversion software that utilizes both cores on dual-core processors?
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slackophage
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Re: Can someone explain processors to me? [Re: Gumby]
#8127584 - 03/10/08 01:59 PM (16 years, 2 months ago) |
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Hyperthreading makes one CPU pretend it's two CPUs by some form of magic I never bothered to completely understand. Most of the stuff I deal with performs worse with HT enabled, it gets turned off.
2cpu had a good write-up and benchmark on it while back.
http://www.2cpu.com/articles/42_2.html
Not sure about the video apps, not a windows user. But if an app is multi-threaded, they usually like to brag about it. Check the docs or features for the app you're looking at.
Found a small list of SMP aware apps, don't know how current it is tho: http://www.denniskarlsson.com/smp/
Edited by slackophage (03/10/08 02:10 PM)
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Annom
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Re: Can someone explain processors to me? [Re: Gumby]
#8127631 - 03/10/08 02:15 PM (16 years, 2 months ago) |
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I don't truly understand processors and can't really help you with video converting software for dual core. I think it would be very easy to write a program for dual core video converting; just cut the movie in half and convert both on a sigle core, then paste together again.
I still have an AMD Athlon64 4000 single core and it works like a horse on the programs I need (and are all still only made for single core), it was only $35.
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Legend9123



Registered: 09/24/06
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Re: Can someone explain processors to me? [Re: Gumby]
#8128054 - 03/10/08 03:57 PM (16 years, 2 months ago) |
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Quote:
Gumby said: So companies are coming out with multiple core processors. Like dual core or quad core... What exactly is a core?
It is basically a processing unit. Think of it as two processors on a single die.
Quote:
Gumby said: I remember reading on here (I think) that most programmers don't program/know how to program for multiple cores. Why is that? Is it just really difficult? What type of programs usually do take advantage of all cores?
The difficulty comes in making sure all of the processes/threads are running in sync. It is much easier to program something that runs linearly than trying to program ten things linearly and making them work well together. That is watered down but should explain why. Usually rendering programs and some games are multithreaded. Recently a lot of your video/audio programs are becoming that way as well.
Quote:
Gumby said: I ask because I have a 3.4Ghz Pentium 4 dual-core (Northwood) processor. Right now I'm converting an AVI to DVD format. When I pull up task manager, it says only 50% of my resources are being used. Does that mean it's only using one core? If the software was capable of using 100% of my resources would the conversion go faster? Basically: am I getting all the power out of my CPU that I should/could be getting?
When you pull up task manager, click on the performance tab. It will show you how much load is on each core. What software are you currently using?
-------------------- Those who would give up a little freedom to get a little security shall soon have neither. -Benjamin Franklin
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Gumby
Fishnologist


Registered: 06/13/01
Posts: 26,656
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Re: Can someone explain processors to me? [Re: Legend9123]
#8137506 - 03/12/08 03:48 PM (16 years, 2 months ago) |
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I'm using WinAVIVideoConverter 7.1.
But I'm getting ready to ditch that. I was told that the new Nero will convert the files and burn them. With this, I have to convert first then burn in my old version of Nero.
So as far as turning of hyperthreading goes... I'm assuming I just do that in the BIOS? Any idea where that setting would be? Think I'll see some kind of performance leap if I turn it off? I think I might do it.
On to a separate issue involving the processor. I've tried overclocking it via the automatic settings in my BIOS(5%, 10%, 15%, 20%). The automatic setting also overclocks the bus on the RAM. Ever since I upgraded to 2GB RAM, I haven't been able to do more than 5% OC. I've tried manually OCing it by changing the voltages on just the processor(didn't touch RAM settings) and my computer just refuses to boot. Any ideas why? Perhaps HT is messing it up?
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supercollider
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Re: Can someone explain processors to me? [Re: Gumby]
#8141929 - 03/13/08 03:51 PM (16 years, 2 months ago) |
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I don't think you want to (or can) turn off HT on a multi-core CPU. As for your overclocking, it sounds like your memory might not be up to the task. Not all RAM is created equal for overclocking purposes. One thing you could try would be to loosen the memory timings. Here's an article explaining that: http://www.techpowerup.com/articles/overclocking/AMD/memory/131
-------------------- Supercollider? I just met her!
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Legend9123



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Re: Can someone explain processors to me? [Re: Gumby]
#8143380 - 03/13/08 08:38 PM (16 years, 2 months ago) |
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SC is right on, some memory cant handle being clocked like that. The timings might help. An alternative is changing the FSB/memory divider. It allows you to raise your FSB speed while keeping your memory clock the same. This article may help even though it is a wiki: http://en.wikipedia.org/wiki/Memory_Divider
-------------------- Those who would give up a little freedom to get a little security shall soon have neither. -Benjamin Franklin
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Seuss
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Re: Can someone explain processors to me? [Re: supercollider]
#8144832 - 03/14/08 04:34 AM (16 years, 2 months ago) |
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> I don't think you want to (or can) turn off HT on a multi-core CPU.
HT has nothing to do with multi-core. It has to do with instruction scheduling allowing the OS to schedule a different thread when the running thread is starved for CPU resources. On the Pentium 4, there is a design flaw in the replay system (part of the CPU that reschedules mis-scheduled out-of-order instructions) that causes HT to degrade overall system performance in many cases. Xeon chips are not effected by this problem. The Prescott architecture improved HT performance quite a lot, but not enough to overcome the shortfalls.
If you really want to understand the source of problem (it isn't easy reading): http://www.xbitlabs.com/articles/cpu/display/replay.html
-------------------- Just another spore in the wind.
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Gumby
Fishnologist


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Re: Can someone explain processors to me? [Re: Seuss]
#8149688 - 03/15/08 02:15 PM (16 years, 2 months ago) |
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I turned HT off and my system seems to be running a little smoother now.
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