32bit kernel on dual core amd
 

This may be a stupid question, but at this point is there any reason to continue to run a 32 bit version of linux? Some people say yes, and some say that the 64 bit versions have been thoroughly tested and work fine. Does the 32 bit kernel fully optimize the dual core processors?

I'm using Fedora 64-Bit on my PC since F7 or F8 and cannot say that I had any problems that I'd not have with the 32-Bit version which powers my notebook.

I clearly suggest using the 64-Bit version.

...for some people yes, and for some people no.

...both of those would be correct, then.
The phrase 'optimise the dual core processors' is a bit obscure; I assume you mean use (or optimise the use of) to the maximum. Well, if you have more than 4G of memory, you'd probably say no....well unless you were considering the PAE kernel, although you may prefer not to go there.

Really, the disadvantage of the 64 bit is if you want proprietary apps, and the app provider hasn't (yet) provided a 64 bit version. You can get round this, but if 32 bit just works for you, you might ask why you would bother. (And its less of a problem than it once was, as proprietary software providers get with it.)

32/64-bit has no relation on whether all cores are used. SMP/non-SMP does; all modern Linux distros have SMP-enabled kernels and will use all cores.

We are just on the cusp of widespread 64-bit adoption. I can tell you that Flash and Java work in my browser on 64-bit Linux.. but on the other hand I have 2GB RAM so there's no real benefit for me going 64-bit.

As computers start to come with 3.5+ GB RAM routinely, that will also spur 64-bit adoption and development. (With a 32-bit processor, you only get 4GB of total address space, including RAM and video card RAM).

What's wrong with PAE? I see it as an advantage as it also enables the NX-bit (No eXecute) of the CPU.

Usually distributions provide both 64- and 32-bit software in their repositories.

As said, on my PC I use Fedora 64-Bit. Skype is 32-bit, thus has dependencies which are 32-bit. They are all available in the Fedora-repos.

Yes, I ran 64 bit Kubuntu 8.10 for a while, but it seemed to have issues, unrelated to it being 64 bit, just the fact that it didn't seem as polished as it could be. I am now running mandriva 2009 with a 32 bit kernel and it runs like a dead duck on this fast machine. Although watching the cpu usage it stays low, it just seems way too slow. That is why I thought maybe using the 64 bit version would make it move a little quicker.

The major advantages of the 64-bit version come to play when you're
about fast memory usage. So, if you're planning on using a RDBMS
like PostgreSQL on your machine, by all means. In terms of performance
(CPU utilisation) you won't see much difference.

That said: given the word-length in 64-bit you'll probably see the
64 bit counterparts of your programs consume more RAM than the 32 bit
versions ... ;}


Cheers,
Tink

Well here is a question maybe slightly unrelated, but why does it seem like the system always utilizes one core more than the other? It seems like a large disparity watching the cpu usage graphs, and it doesn't seem to be the same one all of the time. Sometimes cpu0 is high while cpu1 is low, or vice versa?

They just switch around.

Applications do have to be written to take advantage of multiple cores.

There is an amount of feeling out there that PAE is a bit of a hack that shouldn't have got in (http://linux.derkeiler.com/Mailing-L.../msg01728.html, http://www.linuxquestions.org/questi...hel5.2-689609/). I am currently using it on my laptop, so my personal objection isn't very strong, but, for others they may have other opinions.


Which is absolutely fine, unless you need a bit of proprietary software that the closed supplier doesn't make available. There is nothing that the distro can do to fix that, really, until the proprietary supplier decides that its worth their while to fix the problem.

Tinkster wrote:
Have you measured it; I wouldn't have expected it to be all that much; of the order of 5-10%, I would have guessed.

Big yes; if you have a database that is over 4G (or even close), 64 bit seems sensible. But again, within the limits of a 32 bit kernel, I wouldn't have expected the speed to be noticeably different, so I'd be interested if anyone has test results to share.

Thanks for those links. I'm gonna dig into it.