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Old 12-31-2008, 04:00 AM   #1
Xenarios
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x86 or x86-64?


Hello, i am wanting to try Linux again, but i was wondering if there were any drawbacks of using a 64-Bit Linux distribution.

Also i take it that i will have to use 64-Bit to utilise 4GB of RAM.

Thanks in advance.
 
Old 12-31-2008, 04:26 AM   #2
Isix
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Hi

I am not sure if I do the right thing, if I ask you do check the following opinion.

http://www.linuxforums.org/forum/lin...bit-linux.html

Have a nice last day of 2008.
Isak
 
Old 12-31-2008, 04:30 AM   #3
Xenarios
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Thank you, very useful link
 
Old 12-31-2008, 04:46 AM   #4
Junior Hacker
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That's a very old article, many of these "views" are not applicable anymore. Do more research before coming to a conclusion.
It's near impossible to match you up with the best fitting architecture without knowing what you use the computer for.
 
Old 12-31-2008, 04:56 AM   #5
jschiwal
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If you have 4GB of ram, I would recommend a 64-bit bi-arch distro. Some programs will be 32 bit but most will be 64 bit. The main advantage of a 64 bit distro is being able to handle more memory.
 
Old 12-31-2008, 06:49 AM   #6
IBall
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My theory on 32bit vs 64bit is you have a 64bit processor, so you may as well use it.

I use Ubuntu 64bit on my main desktop, and it seems to run every application that I want it to (including Flash, and all the multimedia codecs I can think of).

Most of the views you read on this subject are outdated. A few years ago, there were some serious drawbacks to 64 bit. Not anymore.

--Ian
 
Old 12-31-2008, 09:21 AM   #7
weibullguy
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I've been using Linux on a 64-bit machine for about four years (well, OK, my wife just stole my x86_64 machine so I'm temporarily on 32-bits, but that's another story). Anyway, I've never had any significant issues with 64-bit as long as I've used a multilib distro. AMD designed the x86_64 architecture to be multilib, the standards recognize this fact, and non-multilib x86_64 distros can cause (solvable) problems. So, I second jschiwal's motion for a multilib distro.

There are some closed-source apps like Flash, Adobe Reader, Ahead Nero, Lightscribe, and RealPlayer to name a few that are only available as 32-bit. There are also some open-source apps that are PITAs as 64-bit. Wine and VirtualBox are two that come to mind. Other that were written with the apparent belief that 32-bit was the limit can also be a PITA.

If you think running 64-bit is going to be "like really super fast" compared to 32-bit, you will probably be disappointed. The difference in speed to execute an instruction is measured in nanoseconds. You need a lot of nanoseconds before the frail human mind can notice a difference. If you do numerically intensive tasks like photo or video editing, audio encoding/decoding, or something just mathematical, you will notice a difference. For example, I run a simulation that requires millions of individual calculations. On a 32-bit machine, it takes about 40-hours to complete. On a 64-bit machine it takes about 28-hours. Yeah, you notice, but only if the task takes a long time to begin with.

Anyway, my

Last edited by weibullguy; 12-31-2008 at 09:40 AM.
 
Old 12-31-2008, 10:25 AM   #8
johnsfine
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Quote:
Originally Posted by weibullguy View Post
I second jschiwal's motion for a multilib distro.
I agree, but I'll comment that the distribution descriptions I've seen haven't said "multilib" even though the distributions are multilib. Most x86-64 distributions are multilib, so if you just select x86-64 (aka AMD64) you are almost certainly getting multilib.

Quote:
If you think running 64-bit is going to be "like really super fast" compared to 32-bit, you will probably be disappointed.
I can say for sure that some programs are significantly slower in 64-bit than in 32-bit and some are significantly faster in 64-bit and some of those differences go in the opposite direction as you would expect (even given a very good understanding of the underlying issues).

I think that a typical user won't see enough difference in either direction to really notice. But I can't say that "for sure".

I would (and did) select 64-bit rather than 32-bit, but I don't think it really makes a lot of difference.

Quote:
The difference in speed to execute an instruction is measured in nanoseconds.
No way. First, nanoseconds is a LOT per instruction. Second, the difference in speed per instruction is typically zero and when it isn't zero, the 32-bit instruction is probably faster.

The advantage of 64-bit comes on the occasions when you need fewer instructions to do a job in 64-bit mode than you would need in 32-bit mode. If you execute the same number of instructions the 32-mode will be at least slightly faster.

Quote:
If you do numerically intensive tasks like photo or video editing, audio encoding/decoding, or something just mathematical, you will notice a difference.
A few photo or video editing tasks can make good use of super large amounts of virtual memory when it is available and fall back on file I/O when that virtual memory is not available. So 32-bit mode runs slower because of the OS overhead to service those file I/O requests and maybe a lot slower if the file caching is less effective so more file I/O requests go to the actual disk relative to virtual memory accesses going to the swap area.

Quote:
For example, I run a simulation that requires millions of individual calculations. On a 32-bit machine, it takes about 40-hours to complete. On a 64-bit machine it takes about 28-hours.
Do you mean on the same hardware and only the software is different? Otherwise, I'd guess the difference is the hardware, not the choice of 32-bit vs. 64-bit mode for the software. Also, you must mean billions, not millions of individual calculations and many billions, not just a few.

The simulations I work on run a little slower in 64-bit mode than in 32-bit mode (best speed is actually the 32-bit simulator running under a 64-bit OS). Some of the problems are just too big to simulate in 4GB (max for 32-bit program in 64-bit OS) so we need a 64-bit simulator even though it runs a little slower.

If you meant the same hardware and you got that big a difference, I think the reason is that the 32-bit compiler you used did a rotten job of dealing with the limited number of registers in x86. x86-64 has twice as many general registers and twice as many xmm registers as x86. When the compiler can't deal well with the x86 shortage of registers, it generates lots of extra instructions to "spill" and reload values and/or it works directly with memory for values that should have been in registers.

For the end user, for those few programs where that effect is significant, that is a big advantage for 64-bit mode. The end user cares about results, not reasons. So it doesn't matter that the important issue has little to do with the primary difference between 64-bit and 32-bit and much more to do with weakness in the compiler.
 
  


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