As I recall, this isn't quite true...from what I've read and experienced, the kernel will swap out old pages for its caching strategy even if some memory is left.
Originally Posted by Hephasteus
That seems to be true and the reason why you should use a swap partition even with plenty of RAM (though in this case that partition can be very small, as long at it's there). There will be a little bit of swap used for optimization purposes even if you had something like a 500GB RAM machine.
It's hard to figure out. I remember working on systems with sco unix years ago that used swap alot but those where the 4mb 8mb ram days. I can't remember if swap got used much with redhat 7 which i ran on very old hardware but since I've been running fedora from 4 to 10 I've never seen swap used with 1gb 1.5gb 4gb. My old system got flakey with dual channels and I had to run some with single channel here and there and I think it swapped a bit when I ran 512mb. Reguardless linux really busts it's butt trying to stay within 512mb from what I've seen with it. It keeps active stuff from about 360 mb to 490 mb most of the time on my system. But wine and VM's throw alot of that out the door.
But even vista doesn't need much ram if you run it in 2d graphics. So it seems that heavy ram usage won't come till we see heavy 3d usage.
Still like to understand that all better. It just seems so modularized and there's so much sharing and optimizing of the sharing profiles it's very hard to nail down. It all works like a pool and it seems so good at it's job that increasing the pool has little effect.
My gut says 512mb is where it's at for pure linux. 1gb for pure linux plus wine and 512mb plus whatever size you set for each VM for virtualization.
I played everquest on PEQ server while back and the server for that thing is very modest with only 2gb of ram. It never swaps but my gut tells me it could use tons more ram but never could figure out what perl 5.0 was doing well enough to suggest configuration changes to change it's pool profile. It would rather monkey around with the sharing pool than use more ram. The monkeying around would cause it to ignore the network so long that it dropped dozens of users at a time.
Ok, that was the argument I needed...
Originally Posted by Hephasteus
$35 for 2GB is not bad.
Oh, now I notice! There are 4 slots, which handle 2GB each!!! And, I have 2 free! I had forgottened.
So, my next thread would obviously be, Wouldn't 8GB RAM be worth an additional $70?
Did the new 2GB help or make any difference? Well, I do think Google Earth load faster, even when I had like six, seven or eight Iceweasel windows open, and playing Amarok, and updating in the background, and smiling at the System Monitor. It might be a psychological effect of sorts only, but my smile outweighs that.
I recently upgraded from 4 to 8GB of RAM, simpy because we've hit the bottom of DDR2 prices (they can only go up from here and, indeed, they are slowly starting to).
Did I notice a difference? Only in three cases: a) exporting a ridiculously complex model from blender to some other format (the python exporter allocated something close to 4.5GB of memory!), b) increasing memory limits in GIMP so you can work with 16+MPixel images in GIMP and c) running >3 VMs at the same time.
For everything else, 8GB is overkill.
I'm still running with the 1 Gb I got when I bought my laptop. There were only two instances when the thing started to swap (and eventually crashed). One was when, out of curiosity, I decided to render a 3D scene from some molecular simulation program to a file (ps, I think), at ridiculously high quality settings. It choke badly. The other was when working with Inkscape, Gimp, a WindowsXP virtual machine and some other visualization tool performing operations on a fat tiff file (on top of the regular browser, mailer, pdf viewer and what have you).
Most of the time, however, I don't seem to need any more memory. Having said this, if I had a bit more I'd do more often the trick of loading a movie to ram to watch it without banging the HD.
Increased ram does help with some things (gimp and 16k x 16k pixel images - I'm another who sometimes uses that), but I'd say faster ram is more important if you're not dealing with large data sets. Well, I should say lower overall latency ram is more important. Of course, more memory and lower latency is better.
I finally got fedora 10 to use swap with 3.4gb (512mb shared ram to video). Brasero used up all my ram and from terminal
-/+ buffers/cache: 568068 2976008
* for spaces.
Last edited by Hephasteus; 04-01-2009 at 04:29 PM.