Shared Memory Question

**Lucjan** · 01-14-2007, 20:30

Exactly what does shared memory mean/do, and is there any way to "unshare" it?

**Blodrast** · 01-14-2007, 21:23

It depends on the context.

In an architecture context, you can have a shared mem. architecture, vs. a distributed memory one. The shared memory architecture means that all CPUs will be able to directly access the entire memory, and they all see that entire memory space. In the distributed memory architecture, the CPUs are usually in different physical machines, and they only see their local chunk of memory, not the entire memory space; however, they may be able to access other CPU's local memory chunks, but NOT directly - only via the other CPUs.

Obviously, this is a simplified and generalized explanation ;)

Now, in the "software" context, say you have one machine, and a bunch of programs. Normally, as a basic OS security design, processes will run in separate memory spaces, and won't be able to access each other's memory. But if, for some reason, you WANT some of your processes to be able to access a common chunk of memory, you can declare a region of memory as "shared", and all the other processes will be able to access it directly.

Again, this is a simplified explanation.

I hope this at least answers the first half of your question.

Your question was however more than vague, and I am not sure what you mean by unsharing. What's your context ?
In the second case I mentioned, it's pretty obvious, if you don't want that shared memory, you don't declare it :) But I'm guessing your context is a different one.
So, more details are required.

**Lucjan** · 01-14-2007, 22:06

I know it was vague, because I'm not sure what I'm talking about myself.

I was told the reason my laptop, which has a 256 mb GeForce 5150 Go, runs M2 slower than my desktop's old graphics card, a 256 mb ati x1300 pro, is because the laptop's graphics card is using shared memory.

The laptops 1.8 dual core is faster than my desktop's 2.8 single cell, so there's no issue there, it's just that shared memory business....

Basically I just want my game to run better on the laptop (runs with most settings on medium, but some have to go to low) because my desktop is currently out of commission, hard drive crashed big time. Any ideas?

**Phatose** · 01-15-2007, 07:22

A 5150 isn't going to run it nicely any way you look at it. The memory sharing is just a symptom of the bigger problem that it's just not a very good video card. The FX series just ain't great, and while an X1300 is no beast, the 5150 is more or less a leper.

At any rate, unsharing the memory isn't going to happen. It's basically borrowing system memory for texture storage - so unless you decide you don't like textures, you're not gonna change that.

**sapi** · 01-15-2007, 09:13

To begin with, that's not a great card (but that's what you have to expect from a laptop)

Shared memory means that the card 'steals' system memory. This is slower and has teh added disadvantage of bottlenecking low-end systems by using up all the memory (or at least 256mb of it)

**Lucjan** · 01-15-2007, 09:58

Hm...rather disappointing for a system I paid 1,400 for.

Better question then. I've been having a problem with my desktop that seems irreversable, and the desktop itself is rather aged at 4 1/2 years, so I think I'm just going to replace the parts I haven't replaced in the last year.

So, basically, I need a hard drive, motherboard, and cpu. Any suggestions?

As far as things I've bought recently and intend to keep, I've already got an nvidia Geforce 7600 GS using the agp 8x slot, so I'd prefer a mobo with both agp and pci xpress slots in case I want to use pci express in the future. Using two sticks of 1 gig ddr ram right now. Have a 430 watt power supply.

**Phatose** · 01-16-2007, 04:05

AsRock 939Dual-Sata. AFAIK the only AGP/PCIe mobo on the market where AGP isn't completely tanked.

CPU - get an AMD dual core. Either a cheapo Opteron 165 if you're an overclocker, or as decent an X2 as you're willing to pay for if not. Since you're using DDR1, and since the only AGP/PCIe mobo I know of it the ASrock above, a Core2 Duo isn't workable.

HD - eh...whatever.

**Husar** · 01-16-2007, 12:25

Originally Posted by Phatose

AsRock 939Dual-Sata. AFAIK the only AGP/PCIe mobo on the market where AGP isn't completely tanked.

CPU - get an AMD dual core. Either a cheapo Opteron 165 if you're an overclocker, or as decent an X2 as you're willing to pay for if not. Since you're using DDR1, and since the only AGP/PCIe mobo I know of it the ASrock above, a Core2 Duo isn't workable.

HD - eh...whatever.

Wrong.
I myself use an AsRock 775 Dual-VSTA.
It supports the Core 2 Duo, has AGP8x, PCIe x4(x16 cards do fit and work but run only at PCIe x4)
Concerning RAM, it has two slots for DDR1 up to 400MHz and two slots for DDR2 up to 667MHz, you can't use both simultaneously though.(I once had a board that ran Edo- and SD Ram simultaneously IIRC, but that was ages ago)

It's also outfitted with four internal and two external SATA 2 connectors.

I bought this along with an E6600 and have since upgraded from an NVidia 6600GT AGP to an NVidia 7950GT PCIe and from 1GB DDR1 to 2GB DDR2 and so far the system runs pretty stable and pretty fast, a great piece for upgrading IMO but because of the slow PCIe connection I am now looking to get a somewhat decent NForce 6 board.

**Lucjan** · 01-16-2007, 13:43

I'm leaning towards (since I'm getting my tax return money very soon) simply tanking the agp card altogether and buying the pci x16 version of the same card.

If that were the case, any ideas on the mobo and cpu? I am most definately going to be getting a dual core, but as for whether I go amd or intel I'm not sure, I've always used intel for almost everything but my laptop runs on amd, and I haven't had any problems with it but because of the graphics card difference can't compare it to my intel cpu on the desktop.

**Husar** · 01-16-2007, 17:48

Originally Posted by Lucjan

I'm leaning towards (since I'm getting my tax return money very soon) simply tanking the agp card altogether and buying the pci x16 version of the same card.

If that were the case, any ideas on the mobo and cpu? I am most definately going to be getting a dual core, but as for whether I go amd or intel I'm not sure, I've always used intel for almost everything but my laptop runs on amd, and I haven't had any problems with it but because of the graphics card difference can't compare it to my intel cpu on the desktop.

You'd still have to look for a mobo with DDR1 slots and since these are either rare or old, you could go with the one I have or get a decent one and also buy 2GB DDR2 memory for about 200$ in addition to the rest.