Do I need SWAP on for my Laptop?

mickyg · 08-13-2005, 08:08 AM

Hi all,

My Laptop h/w is:

Celeron-M 1.5 Ghz
1Gb RAM (upto 64Mb shared with graphics card)
60Gb HD.

As the subject says, I want to install Mandriva (probably with all the bells and whistles and eye candy) but I don't know whether I really need a 2Gb SWAP partition (as I understand it the SWAP is generally 2x physical RAM) given that I have 1Gb RAM already. Please advise.

Thanks in advance.

linmix · 08-13-2005, 08:47 AM

From what I've read it's best to have a swap file. Linux makes maximum use of swap and ram memory to make the system run as smooth as possible. However, (again from what I've read) if you have 1GB of RAM there's no need to do 2xRAM for SWAP. I'd go for 1GB SWAP.

ctkroeker · 08-13-2005, 11:07 AM

You actually won't need a SWAP. I have 512MB Ram and it doesn't touch the SWAP.

Matir · 08-13-2005, 11:19 AM

I would create a small swap partition of about 256MB. Swap doesn't need to be 2xRAM, that's just a rule of thumb that's becoming outdated as RAM becomes more plentiful. The small swap partition will allow the virtual memory manager to run most efficiently.

J.W. · 08-13-2005, 12:56 PM

I'd second Matir's suggestion of a 256Mg swap. For systems with at least 256 or 512 of RAM, it is unlikely that swap would ever see any significant use. -- J.W.

guzzi · 08-13-2005, 01:32 PM

swap file space is necessary for.....

On a box dedicated to being a NAT/firewall, with about 90M of RAM, and 100M of swap, no swap is ever used. On this box an average of 27M of RAM is all that ever used.

On another box with 1G of RAM and 100M of swap, some swap is always in use. This box is used for everything from folding@home (when in season/cold outside) to kernel compiling, music cdburning etc...

It looks like swap depends on your requirements.

mickyg · 08-14-2005, 06:32 AM

Well as I said, I want KDE with all the graphical bells and whistles but I'd also be looking at have a couple of VM's too.

Would the general concensus be a 256Mb swap?

syg00 · 08-14-2005, 07:03 AM

You said laptop.
If you plan to use Suspend2, I believe it writes the memory image(s) to swap.
Wouldn't pay to scrimp on swap IMHO.

mickyg · 08-14-2005, 08:38 AM

suspend2? is that the linux equivalent to the hibernation function in xp?

If I wanted to do that I'd need at least 1G swap wouldn't I?

Matir · 08-14-2005, 04:20 PM

Yes, mickyg. Well, you can get away with somewhat less due to compression, but it's hard to determine how well the compression algorithm will run on any given data set.

Half_Elf · 08-15-2005, 12:13 PM

if you want to use hibernation, my guess would be to go with more than 1 GB of swap, even if it's a damn waste of space... In case you RAM is "full" you will need 1 GB of swap to hibernate, plus what swap will be in use at the time of hibernation.

sundialsvcs · 08-15-2005, 01:57 PM

I would remain with the old adage that "2x RAM" is an appropriate amount of swap space, and that you should have it.

I'm not sure that I would plan to use hibernation ...

mickyg · 08-15-2005, 03:39 PM

Would you care to elaborate as to why?

I'm not intending to use it all the time, I just don't want to have 256MB swap and find that I can't use it at all.

Also, this might be a really stupid obvious question but, if I have more swap does that mean I can have more programs open and my computer will generally run smoother or will it not make much of a difference given the amount of physical RAM I have?

linmix · 08-15-2005, 03:54 PM

Just tried what my machine will do: got 500+ ram and whatever I do, I never get above 200mb swap

syg00 · 08-15-2005, 07:11 PM

What's a bit of (potentially wasted) disk space these days ???.
Lots of desktop users never see it used.
If you need to swap, and you don't have any active, something (maybe everything) dies a horrible death.
Then there is Suspend2 and its ilk.

Your choice what is acceptable risk.

As an aside I run a Gig plus 5 Gig swap, and I regularly see 2 Gig of the swap actively in use.
Not your typical user, but there are cases where it really gets used.