Memory usage on 64-bit OS

[valle2000]

I have 12 GB RAM and I know 32-bit software (like WoW) only can use 3 or 4 GB of it. But does this mean all five instances of my WoWs must share the same first 4 GB and leaving the rest 8 GB complely unused? Or can they spread out on all those 12 GB but each application can only access it's own small pocket of memory?

[ILikeTwins]

I had a long explanation but it got eaten by my browser

There are hardware (64 bit capable CPUs for physical addressing) and software issues (64 bit Operating Systems) but basically it is the operating system that manages the memory that an application can use and not the application itself.

A 32 bit operating system can handle approximately 4GB of addressable memory. This is because each bit in the address can only be a 1 or 0 so 2^32 addresses equals roughly 4GB (there is some overhead in windows for reserved spaces etc). Most 32 bit Windows systems will show that it recognizes 3.5GB of RAM because of the overhead and other reasons that I wont get into.

A 64 bit operating system can handle 2^64 addresses which is roughly 18 million gigabytes (more than anyone can possibly put in their computer right now). That means that a 64 bit operating system is required to address all 12GB of RAM that you have. Most 32 bit applications can still run fine in a 64 bit environment. The operating system just manages them differently than they would a 64 bit application.

Hope this helps
Twins

[Sajuuk]

I had a long explanation but it got eaten by my browser

There are hardware (64 bit capable CPUs for physical addressing) and software issues (64 bit Operating Systems) but basically it is the operating system that manages the memory that an application can use and not the application itself.

A 32 bit operating system can handle approximately 4GB of addressable memory. This is because each bit in the address can only be a 1 or 0 so 2^32 addresses equals roughly 4GB (there is some overhead in windows for reserved spaces etc). Most 32 bit Windows systems will show that it recognizes 3.5GB of RAM because of the overhead and other reasons that I wont get into.

A 64 bit operating system can handle 2^64 addresses which is roughly 18 million gigabytes (more than anyone can possibly put in their computer right now). That means that a 64 bit operating system is required to address all 12GB of RAM that you have. Most 32 bit applications can still run fine in a 64 bit environment. The operating system just manages them differently than they would a 64 bit application.

Hope this helps
Twins

wat, shush and don't reply unless you're actually trying to answer the question. You added nothing (Nothing! neither am I right now, but I will shortly)

Second of your posts: wat. Explanations are fun and all, but not needed in this thread. A yes/no suffices. On that note: yay learning?


OP: Yes, you are not limited to four gigabytes of ram for all of your instances. Each will use up to 2GB of ram, up to a total of 10gb. (As per svper's post)

[thefunk]

wat, shush and don't reply unless you're actually trying to answer the question. You added nothing (Nothing! neither am I right now, but I will shortly)

Second of your posts: wat. Explanations are fun and all, but not needed in this thread. A yes/no suffices. On that note: yay learning?


OP: Yes, you are not limited to four gigabytes of ram for all of your instances. Each will use up to 2GB of ram, up to a total of 10gb. (As per svper's post)

I for one have learned something today, which a yes/no answer wouldn't have.

[Sajuuk]

I for one have learned something today, which a yes/no answer wouldn't have.

la de da? He still didn't really answer the question flat-out. Yes, interesting informations is fine, but he still didn't answer the question.

[ILikeTwins]

My original post had the answer but I was so irritated by my browser eating it that I didn't completely explain it again. Honestly not sure why it made you so angry.

There is no need for you to come in here an insult people who are trying to help. If you wanted to help then post a helpful message but there is no reason to act like you are 10 years old. Some people actually like to learn things.

[alcattle]

to OP:right but also wrong,
The only software controlling amount of RAM is the OS. Windows this case. The base 32 - bit OS only sets up 4 gigs of memory locations. From that number, the OS uses some, drivers use more so you end up with 3.5 gigs or so of usable RAM. Programs take memory from that amount.
64 bit OS will allow a huge number of locations, forget the number but more memory then your PC can hold.

[Svpernova09]

At this point in time WoW is not supposed to use more than 2 gigs of RAM per instance. (5x WoWs max would ever use 10 gigs)

http://forums.worldofwarcraft.com/th...1#242589026545

We're not enabling the 3 GB switch on World of Warcraft as its memory management system is built to handle keeping things under 2 GB. It may change in a future version but the current one won't. Only StarCraft II has it.

[valle2000]

But can a 32-bit application running in my 64-bit OS utilize any of the memory above the first 4 GB?

A simple theoretical example. If we pretend the OS uses 1 GB of memory and two 32-bit applications are launched using 3 GB each, can the first program be placed in memory range 2-4 GB and the second in memory range 5-7 GB? Or must they both be placed within those first 4 GB since they are 32-bit and are incapable of allocate any memory above the 1-4 GB range?

Hope you understand how I mean.

[alcattle]

But can a 32-bit application running in my 64-bit OS utilize any of the memory above the first 4 GB?

A simple theoretical example. If we pretend the OS uses 1 GB of memory and two 32-bit applications are launched using 3 GB each, can the first program be placed in memory range 2-4 GB and the second in memory range 5-7 GB? Or must they both be placed within those first 4 GB since they are 32-bit and are incapable of allocate any memory above the 1-4 GB range?

Hope you understand how I mean.

yes although some older programs need a little help with newer 64 bit OS