4
Scratx, on 18 December 2014 - 07:47 PM, said:
Hmm. Okay, I'm going to get technical. THIS IS GOING TO GET REAL!!!! 
(if I make a mistake, forgive me)
First of all, a reference point. Every "position" in memory has an address, like every house. This address tells the computer where to look for what you want, just like you'd use an address to find where you need to drive to.
The main difference between 32 bit and 64 bit is that, in 32 bits, all addresses are a value between zero and (2^32)-1, which is exactly 4,294,967,295. In 64 bits, it's a value between zero and (2^64)-1, which is, if I didn't break windows calculator, 18,446,744,073,709,551,616.
This is why it's said that 32bit computers can't benefit from having more than 4GB. Though as it turns out, due to shenanigans in Windows, you can only use 2GB in an application, or 3GB with tricks that are not always safe (read: WILL crash your computer sometimes). Windows itself CAN use the 4GB and even more than that, but that is not relevant here.
In MWO's case, what this means is that instead of being stuck to around 2-3GB tops in memory use, by going 64 bits you can effectively use all the memory you have. This means you can load data to memory and not throw it away just because it's not being used right now, for example. Or use more memory hungry storage techniques which end up being faster to actually use due to details of how it's used.
There are other benefits, though. By going 64 bit, you're also ditching the 32 bit instruction set and going into the 64 bit instruction set on the CPU. While I haven't studied it in-depth, I'm told the 64bit instruction set is a LOT better in many ways, having access to more registers, removing cruft and other nice things that make common operations a lot faster. The more registers thing in particular is very important because operations that involve just registers are ultra-fast, but if you need to handle move values than you have registers for, you have to store stuff in memory, which automatically hits your speed. Accessing cache is several times slower than a register... and you really don't want to know how much slower main memory is.
There are drawbacks as well, though... going 64 bit does have one big penalty. By increasing data size in memory, it also reduces the efficiency of your CPU cache (less actual data can fit in at the same time), which means you'll be paying the cache miss penalties more frequently. Cache miss meaning that the data you want isn't in the (relatively fast) cache, so it has to go fetch it from the OMGSLOW main memory. This is in fact one of the main reasons why going 64 bit isn't a "no brainer" decision to any software engineer. What you gain with the instruction set can be lost with cache misses, depending on your algorithms. (other major reasons include "64 bit executables won't run on part of our potential player base", "we have to support TWO different executables, that's a lot of additional work")
I'm happy to see MWO supporting a 64 bit client because, honestly, 64 bit is the future and it removes a lot of limitations that otherwise need technical work-arounds to do. Wish more games did it, but when it comes down to it, if your game doesn't really need 64 bit, going 64 bit isn't likely to give you much of anything... except a smaller customer base.
One day we'll all have 64 bit OS's. Not much longer, now, I think...
(if I make a mistake, forgive me)
First of all, a reference point. Every "position" in memory has an address, like every house. This address tells the computer where to look for what you want, just like you'd use an address to find where you need to drive to.
The main difference between 32 bit and 64 bit is that, in 32 bits, all addresses are a value between zero and (2^32)-1, which is exactly 4,294,967,295. In 64 bits, it's a value between zero and (2^64)-1, which is, if I didn't break windows calculator, 18,446,744,073,709,551,616.
This is why it's said that 32bit computers can't benefit from having more than 4GB. Though as it turns out, due to shenanigans in Windows, you can only use 2GB in an application, or 3GB with tricks that are not always safe (read: WILL crash your computer sometimes). Windows itself CAN use the 4GB and even more than that, but that is not relevant here.
In MWO's case, what this means is that instead of being stuck to around 2-3GB tops in memory use, by going 64 bits you can effectively use all the memory you have. This means you can load data to memory and not throw it away just because it's not being used right now, for example. Or use more memory hungry storage techniques which end up being faster to actually use due to details of how it's used.
There are other benefits, though. By going 64 bit, you're also ditching the 32 bit instruction set and going into the 64 bit instruction set on the CPU. While I haven't studied it in-depth, I'm told the 64bit instruction set is a LOT better in many ways, having access to more registers, removing cruft and other nice things that make common operations a lot faster. The more registers thing in particular is very important because operations that involve just registers are ultra-fast, but if you need to handle move values than you have registers for, you have to store stuff in memory, which automatically hits your speed. Accessing cache is several times slower than a register... and you really don't want to know how much slower main memory is.
There are drawbacks as well, though... going 64 bit does have one big penalty. By increasing data size in memory, it also reduces the efficiency of your CPU cache (less actual data can fit in at the same time), which means you'll be paying the cache miss penalties more frequently. Cache miss meaning that the data you want isn't in the (relatively fast) cache, so it has to go fetch it from the OMGSLOW main memory. This is in fact one of the main reasons why going 64 bit isn't a "no brainer" decision to any software engineer. What you gain with the instruction set can be lost with cache misses, depending on your algorithms. (other major reasons include "64 bit executables won't run on part of our potential player base", "we have to support TWO different executables, that's a lot of additional work")
I'm happy to see MWO supporting a 64 bit client because, honestly, 64 bit is the future and it removes a lot of limitations that otherwise need technical work-arounds to do. Wish more games did it, but when it comes down to it, if your game doesn't really need 64 bit, going 64 bit isn't likely to give you much of anything... except a smaller customer base.
One day we'll all have 64 bit OS's. Not much longer, now, I think...
Long story short... 64 bit isn't the future, it is the the present and developers have been half-assing it for a long time with regards to stepping up and forcing it as the standard. No offense, but I call a Spade... a Spade.
