michaelsil1

64bit Computing?

Recommended Posts

All I seem to hear about lately is Athlon XP64. Is anyone out there running this system and do you notice any significant advantages.

Share this post


Link to post
Share on other sites

There are no significant advantages to the average user. The main reason to go 64 is the ability to use more RAM.

And most people simply dont need more than the current 4GB that current processors can handle.

Share this post


Link to post
Share on other sites

the current 4 GB are a joke anyway since WindowsXP can only use 2 GB anyway. On the other hand, the Athlon64 (and the A64-FX) are screaming fast in most applications but they are still hurt by the fact that there are only very few drivers out there.

I am running Longhorn64 on one of my boxes --- it is still more of an alpha version but it is kind of fun. WindowsXP 64 is actually pretty mature by now, the only issue is that there are still only few applications that are ported to the 64 bit OS but on the other hand, quite a few of the 32 bit applications do see some performance increase under Windows64.

Whether you need it or not is a different question altogether. I just upgraded my personal box from a Socket7 (pre-AGP) to an AMD MPX system and yes, there is a difference but it is not that my life depended on it..

Share this post


Link to post
Share on other sites

Unregistered, your information is a joke.

XP supports 4GB of RAM. An individual PROCESS can only use 2GB RAM by default, but this can be changed by using the /3GB boot switch, which you may use to set the kernel/user divider anywhere between 2GB and 3GB. Some video drivers require more than 1GB address space, however, and may have problems with this switch.

Blake, there are twice as many registers, so the if someone ports an app to AMD64 then there would definitely be a performance improvement.

Due to the fact that there is far more address space, the burden of limited virtual addresses will also be lessened, allowing better memory utilization with 2GB - 4GB of memory.

Share this post


Link to post
Share on other sites

The perf "improvement" from the additional registers is offset by increased pointer size and increased instruction size.

64bit Computing is mainly useful for people that have a reason to have more than ~4GB of ram in their system and software developers.

Let's see. The peek memory use that I have ever hit in one process was 2 GB, and that was a very contrived example.

Otherwise it is like spending huge sums on improving a p-pro systems performance.

Share this post


Link to post
Share on other sites
The perf "improvement" from the additional registers is offset by increased pointer size and increased instruction size. 

64bit Computing is mainly useful for people that have a reason to have more than ~4GB of ram in their system and software developers.

Not true. Increased pointer size doesn't cost (much) performance and although average instruction size goes up, number of instructions goes down because you have less register 'trashing'.

And 64-bit computing is not the same as 64-bit addressing. Certain kind of algorithms (especially public-key encryption) benefit alot from 64-bit registers.

And it's not just > 32-bit physical addressing, it's also > 32-bit virtual addressing.

Share this post


Link to post
Share on other sites
Isn't it so iA32 has 48-bit virtual addressing since 386?

/casa

No, it has 36-bit physical addressing since the Pentium Pro.

Yes, but virtually 48-bit like

SS:[EBP], DS:[EDI] aso

/casa

Share this post


Link to post
Share on other sites

Yes, I do. You start with a 16-bit selector and a 32-bit virtual address. The base address of the descriptor is added to the virtual address to form the lineair address. AFAIK that lineair address is just 32-bit. The page tables are then used to form the physical address.

I could be wrong about the width of the lineair address, but I'm quite sure it's not 48-bit.

Share this post


Link to post
Share on other sites

32-bit per process because only OS can change the

selectors. But at OS level you've got the whole 48-bit.

Do remember you can have more than one process running

at the time.

/casa

Share this post


Link to post
Share on other sites

Just remember how long it took for Microsoft to fully utilize the features of a 32 bit CPU. Intel was on it's 3rd generation 32 bit CPU before microsoft 95 was released. It took until windows 2000 before Microsoft's mainstream OS finally stripped out all its 16 bit DOS underpinnings.

Share this post


Link to post
Share on other sites
Just remember how long it took for Microsoft to fully utilize the features of a 32 bit CPU.  Intel was on it's 3rd generation 32 bit CPU before microsoft 95 was released.  It took until windows 2000 before Microsoft's mainstream OS finally stripped out all its 16 bit DOS underpinnings.

And?

There are already Windows versions that support 64-bit CPUs and support for AMD64 won't take that long.

Share this post


Link to post
Share on other sites

Hum... all.. this space, that space, bit that and bit this...

to answer the questin...

its the athlon64 (it's got no xp in the name btw) and the reason why you hear about it all the time is they are faster and are going to get even faster than the athlon-xp even in 32bit 'mode' so it is the only AMD processor you going to be buying

(be it athlon64, athlonfx or opteron)

so hey any 64bit benefits are only there if you want to use them (you don't have to)..... it's still going to be faster (and cooler) than you current athlon-xp

:rolleyes:

Share this post


Link to post
Share on other sites
Unregistered, your information is a joke. 

XP supports 4GB of RAM.  An individual PROCESS can only use 2GB RAM by default, but this can be changed by using the /3GB boot switch, which you may use to set the kernel/user divider anywhere between 2GB and 3GB.  Some video drivers require more than 1GB address space, however, and may have problems with this switch.

Blake, there are twice as many registers, so the if someone ports an app to AMD64 then there would definitely be a performance improvement.

Due to the fact that there is far more address space, the burden of limited virtual addresses will also be lessened, allowing better memory utilization with 2GB - 4GB of memory.

Unregistered, your information is a joke. 

XP supports 4GB of RAM.  An individual PROCESS can only use 2GB RAM by default, but this can be changed by using the /3GB boot switch, which you may use to set the kernel/user divider anywhere between 2GB and 3GB.  Some video drivers require more than 1GB address space, however, and may have problems with this switch.

No, it is not a joke. It' sjust that you're talking about different things. You mean Windows XP as released. Unregistered means the 64-bit Windows XP that currently exists in the beta form.

Leo

Share this post


Link to post
Share on other sites
Just remember how long it took for Microsoft to fully utilize the features of a 32 bit CPU.  Intel was on it's 3rd generation 32 bit CPU before microsoft 95 was released.  It took until windows 2000 before Microsoft's mainstream OS finally stripped out all its 16 bit DOS underpinnings.

The 32-bit NT 3.5 was developed before the Pentium was available. Some of the header files have 1990 copyright. As it supported 4 architectures, it did not have DOS underpinnings.

The 64-bit NT 5 version was underway by 1998 on Alphas.

Share this post


Link to post
Share on other sites

Leokor, unregistered WAS talking about XP (Pro, I assume), not the 64-bit ver when he made that comment, and he was flat wrong. He would be even more wrong if he was referencing *any* version of 64-bit Windows, beta or otherwise.

Most sotware vendors don't compile their apps with 4GT support (other than RDBMS), since they don't need more than 2GB RAM for a single process. I neglected to mention that the app has to be compiled with the 4GT flag.

With 36-bit addressing (PAE) and a PAE-aware app (RDBMS only AFAIK), then 64GB of RAM is addressable, although at huge memory overhead and cost, due to the windowed nature (i.e. you can only 'look' at 4GB at a given time, and that 'window' always includes kernel addresses). PAE-aware apps can request different address windows. Casa, your reasoning's correct, but it's only 36-bit at the hardware, and therefore, the OS level. Even if the apps aren't PAE aware, you can run 20+ apps with 2GB RAM-- but you probably would want to run these on different machines or VMs for cost and stability reasons.

XP supports 4GT, but not PAE on x86 systems, but who cares, since no one makes motherboards or uses Xeons for desktops anyway, so the hardware support isn't there. Enterprise versions of Windows Server and server class hardware support PAE. 64-bit Windows supports 512GB RAM, even though 16TB are addressable.

For reference, IBM's AIX supports 1TB RAM on their latest hardware, and HP produces the Superdome which supports, you guessed it, 512GB RAM, and can run Windows Datacenter edition or HP-UX.

So, individual user apps almost never need more than 2GB RAM currently, although some future apps (on-the-fly HDTV editing?) may use more than this. Because they don't need it, they don't compile for it, and some people *DO* need more than 1GB kernel space, so Windows does not default to a 3GB/1GB split.

FluffyChicken's right about the basic question.... Athlon64 is just what he said-- AMD's latest processor which runs very fast in 32-bit x86 mode and slightly faster in x86-64 mode for most tasks.

eyager, go read one of the threads about NT and Win9x. NT was fully 32-bit, and for the most part, so was 9x after people started using 32-bit drivers, although 9x still sucked. You and unregistered can go have a party with the Tom's hardware guys.

Gaws, you're right about investing money in a new OS w/o apps. WOW64 apparently works well, but has a large perf penalty when running more than 1 instance of the same 32-bit image, so it isn't recommended to run Terminal server on 64-bit windows with 32-bit apps.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now