A Question on the RAM Usage of Ubuntu 12.04.02 32bit Desktop

[hangpan]

Based on my "old" experience, 32bit OS should be only support RAM less than 3.5~4GB, but why ubuntu 32bit supports RAM over 4GB. I didn't install any 3rd party software, or anything to do with PAE tools.

Environment:

1. VMWare Workstation 9
2. Ubuntu 12.04.02 32bit Desktop Version

Please refer to the image below:
ubuntu 12.04.02 ram usage.jpg

It would be appreciated for any comments on this.

Thanks,
Hang

[HiImTye]

what kernel are you using?

[deadflowr]

I'st called a PAE kernel.

[mörgæs]

Ubuntu 12.04 comes by default with PAE.

[sanderj]

Based on my "old" experience, 32bit OS should be only support RAM less than 3.5~4GB, but why ubuntu 32bit supports RAM over 4GB. I didn't install any 3rd party software, or anything to do with PAE tools.

Correct: in the old days, 32-bit kernel meant no more than 3.5GB RAM usage.
However, current Ubuntu versions install the PAE kernel by default, and thus will access all the RAM you have got.


So ... boom ... there goes an advantage of 64-bit.
The only advantage of 64-bit I now know, is: no rollover of the TX/RX byte counter in ifconfig ...

HTH

[Paqman]

So ... boom ... there goes an advantage of 64-bit.
The only advantage of 64-bit I now know, is: no rollover of the TX/RX byte counter in ifconfig ...

Not really. A 64-bit kernel supports large amounts of RAM natively, without having to run hacky PAE in userspace.

The main advantage of 64-bit remains the same; it's significantly faster for any kind of serious number crunching (eg: video or audio re-encoding, encryption, compression, etc). PAE is cool, but it's really just a bridging solution while we complete the switch to the new standard of 64-bit.

[Cheesemill]

Although a PAE kernel can address more than 4GB of RAM, it doesn't do it very well.
You may want to read what Linus thinks of the PAE kernel...

Linus on PAE

[hangpan]

Many thanks guys, learn a lot. The kernel version I used is: Ubuntu 12.04.02 LTS

You guys are right, the 32bit 12.04.02 ubuntu came up with pae-enabled, I found it here as well: http://ubuntuforums.org/showthread.php?t=1919647
I know little about PAE, now it's time to pick it up.

Thanks everyone again.

[sanderj]

Many thanks guys, learn a lot. The kernel version I used is: Ubuntu 12.04.02 LTS

You guys are right, the 32bit 12.04.02 ubuntu came up with pae-enabled, I found it here as well: http://ubuntuforums.org/showthread.php?t=1919647
I know little about PAE, now it's time to pick it up.

Thanks everyone again.

Why not use 64-bit?

[KdotJ]

Why not use 64-bit?

+1 to this. If its not too much inconvenience, start again with the proper architecture rather than add on a workaround.