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kprrok
Joined: 06 Apr 2004
Location: KC
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 Posted: Thu Jun 08, 2006 5:20 pm Post subject: CPU Cache |
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Hey guys, I'm looking at building, or buying a cheap 2nd desktop for my wife to use, or for work use. It will be primarily for easy office suite stuff, internet, and music playing. no gaming (other than solitaire) or anything intensive.
So my question is...what does the L1/L2 CPU Cache do? I know that more is good, but if I'm not doing anything intensive, is it really important to have a good cache with the processor?
I'm asking b/c I'm looking at getting a cheapo celery procesor with 16K L1/256K L2 Cache. I realise that a celery isn't the best option, but I'm trying to go cheap on this thing and I don't want to fork out an extra 150.000 for a P4 with better specs.
Thanks for the help guys.
KPRROK |
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ChopChaeJoe
Joined: 05 Mar 2006
Location: Seoul
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| Posted: Sat Jun 10, 2006 8:45 am Post subject: |
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The cache you are referring to is fast memory. A computer chip (brain) doesn't store any information, it only processes it. The hard drive stores a lot of informaion but any tie the brain needs that information it has to send a request to get it and he information (data) has to not only travel over a wire (the bus) to get to the brain but also wait for the read arm of the hard drive to line up with the spinning disk.
All of this takes micro-seconds, but when dealing with millions of bits of data we start to talk about some real time.
It turns out that a lot of time the computer wants the same data over and over. Usually these are computer instructions that are performed again and again.
The cache removes the need for going to the hard drive every time by storing the most recently "fetch"ed data on fast memory chip very close to the brain. The LI will be much faster than the L2, both will be much faster than going to the hard disk.
I would say that for your intended purposes, any used computer built in the last 5 years will do. However, Intel is going to be selling the P4s very cheap in the near future as their factories start churning out more of the dual-core chips. |
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Demophobe
Joined: 17 May 2004
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| Posted: Sat Jun 10, 2006 3:58 pm Post subject: |
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| ChopChaeJoe wrote: |
The cache you are referring to is fast memory. A computer chip (brain) doesn't store any information, it only processes it. The hard drive stores a lot of informaion but any tie the brain needs that information it has to send a request to get it and he information (data) has to not only travel over a wire (the bus) to get to the brain but also wait for the read arm of the hard drive to line up with the spinning disk.
All of this takes micro-seconds, but when dealing with millions of bits of data we start to talk about some real time.
It turns out that a lot of time the computer wants the same data over and over. Usually these are computer instructions that are performed again and again.
The cache removes the need for going to the hard drive every time by storing the most recently "fetch"ed data on fast memory chip very close to the brain. The LI will be much faster than the L2, both will be much faster than going to the hard disk.
I would say that for your intended purposes, any used computer built in the last 5 years will do. However, Intel is going to be selling the P4s very cheap in the near future as their factories start churning out more of the dual-core chips. |
Pretty much, but to the system memory, not the HDD. Disc caching is really slow, but how often does the CPU write back to the HDD these days? Most folks have ample memory....
L1 is on-chip, L2 is on-die. L3 exists as well...commonly on the mainboard...the northbridge.
Speculation, associativity, cache miss, write through, write back...hard to think of on-die CPU cache without thinking of all of this; even for a simple question. I have referred people to the Wiki, as it has a fairly easy to read and clear write-up on this subject.
Celerons are indeed crippled, but only in certain situations will this be noticable, and probably not at all in whet you want to do with it. The celeron is a great chip for wild overclocking just like the old 300A. (did anyone else have one of these too? Madness...)
Do it man. A celeron is a good deal for a second system. Cheap and still pretty fast overall. |
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ChopChaeJoe
Joined: 05 Mar 2006
Location: Seoul
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| Posted: Sat Jun 10, 2006 5:30 pm Post subject: |
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I've got to stop posting when I should be fast asleep. I don;t know how I forgot all about system memory!  |
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Demophobe
Joined: 17 May 2004
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| Posted: Sat Jun 10, 2006 8:25 pm Post subject: |
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| ChopChaeJoe wrote: |
| I've got to stop posting when I should be fast asleep. I don;t know how I forgot all about system memory! |
I know you know....saw the other post saying how long you have been using computers. Glad to see you posting here....more good help has arrived it seems!  |
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ChopChaeJoe
Joined: 05 Mar 2006
Location: Seoul
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| Posted: Sun Jun 11, 2006 3:28 am Post subject: |
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| Thanks for the vote of confidence. I'll help when I can. Usually though, it's me needing the help with these amazing, frustrating machines. |
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