Why swap?

Sören Schneider · 04-29-2006, 03:05 PM

Hi,
why does Linux still need a swap, if a Linuxbox has more than 512M of RAM?

uselpa · 04-29-2006, 03:17 PM

It doesn't, unless you want to use more than your physical memory or some features like suspend to disk.

cs-cam · 04-29-2006, 07:46 PM

Linux should always have a small amount of swap space, whether you have 64MB RAM or 4GB RAM. Search, there were a lot of threads about this a couple of weeks back with extremely good replies

tamoneya · 04-29-2006, 08:14 PM

windows also does this. Just it is called page file. You can see page file usage in windows with ctrl-alt-delete and going to the performance tab.

johnson_steve · 04-29-2006, 08:21 PM

To be honest I have never seen any of my swap used (1024Mb Ram, 512Mb Swap) but just incase you do run out of ram; It's better to be safe then sorry. Is 512Mb of hard disk space that critical? Linux will run with no swap at all, infact I think its the only one that gives you this option windows and mac both 'swap'.

cs-cam · 04-29-2006, 08:53 PM

http://www.linuxquestions.org/questi...highlight=swap
http://www.linuxquestions.org/questi...highlight=swap

I guess that search function must be broken, wonder why it worked for me...

primo · 04-30-2006, 02:58 AM

If you don't use swap, you must fear the infamous OOM (Out Of Memory) killer of the Linux kernel (see /usr/src/linux/mm/oom_kill.c), killing some processes in your system when there's no memory.

jonaskoelker · 05-01-2006, 05:50 PM

Quote:

Originally Posted by primo

If you don't use swap, you must fear the infamous OOM (Out Of Memory) killer of the Linux kernel (see /usr/src/linux/mm/oom_kill.c), killing some processes in your system when there's no memory.

If you do use swap, you should still fear the OOM killer. I've had it kill a runaway frozen-bubble, but only after much thrashing. Having close to no swap would have been good here. But that's just my experience.

sundialsvcs · 05-01-2006, 07:10 PM

Personally, I agree that "you can afford a few megabytes of disk space." Should the system run out of RAM, it's in a pickle... and that swap-space just might save your a*s.

AdaHacker · 05-01-2006, 07:17 PM

Here's an an interesting thread on this very topic from kerneltrap.org. To make a long story short, you can get better performance with swap than without, regardless of how much physical RAM you have.