Another Linux Question: RAM Used?

      • Somebody asked me how much RAM Linux used as compared to Win98, and since I had both I decided to look. Windows says 75% of resources are free, and I can detirmine that isn’t the amount of space left on the hard drive, so I am guessing it is the figure for RAM. 25% of 320 megs = ~80 megs, kinda a lot to not be doing anything, but I guess there’s still 240 megs for whatever I want. — Looking around in the Linux control panel, Mandrake says 156 megs of RAM used! What the hey? And I didn’t even get around to installing any of the bundled software yet! It installed a few things on its own: four GUI’s for instance. Would that make a difference? It seems like I heard that Linux runs better on lower-memory machines because it requires a lot less resources than Windows; is that true or not? Without any ther programs running, what is the penguin doing with that 156 megs of RAM? - MC

The amount of RAM in use has nothing to do with the amount needed. Temporary caches will often use up all available RAM but can flush their data or shift it into virtual memory when more is needed by a specific application.

In general usage, Linux probably needs somewhat less RAM than Windows98 due to lower OS overhead. In practice, ignore the requirements listed on the box and buy as much RAM as you can afford for a given machine. You can never have too much RAM.

Well, if it’s Mandrake, you’re probably using KDE. The KDE libraries are taking up the memory.

It’s misleading to say Linux uses more or less memory than windows. Something like tomsrtbt (Linux on a floppy) will obviously use hardly any, whereas a full desktop envioroment ,loading all libraries at startup, will use a fair bit…

I don’t know how often you reboot windows, but I just did last night (had gotten to the bizaare system failures stage that windows uses as a subtle indicator that it has completely given up on memory management).

This morning? 365 out of 512MB used.

Both Windows and Linux tend to take the memory if it is available, and give it up if it is needed. Until recently, the S.O. was running Windows including IE5.5 on 24MB of ram with reasonable success.

Linux, however, seems to do a better job of keeping track of what memory is in fact in use, and freeing it after a program closes.

Fortunately, Rambooster makes life in Windows a little less painful.

Free resources in Windows is not a measure of how much RAM is free. It is actually a measure of two resouces: The GDI heap and the User heap, which are the graphical resources for the system interface. Every window or icon that needs to be drawn requires User and GDI space. Each is limited to either 64k or 128k (I forget which in windows 95) and both are shared by every program running on the computer. When you see “25% free system resources” that is telling you that 3/4 of the systemwide GDI and User areas are full, NOT that 3/4 of your RAM is in use. For a little more info, see the entry at the Indiana University Knowledge Base or Microsoft Windows System Resources General Information at Adobe.com.

I have never used Mandrake, but some Linux distros come configured out of the box to load up RAMdisks up to a certain percentage of available RAM. Check whether this is what’s going on. It doesn’t hurt your system performance, they get used as buffers, temp files, etc.

Linux uses all available memory as a filesystem cache. When programs need to use memory, the cache is shrunk accordingly. To find out how much memory is being used by programs, run free(1). For example, on my system:


423 [bobort@abacus ~]$ free
             total       used       free     shared   buffers     cached
Mem:        225136     222196       2940      50808       9380     143712
-/+ buffers/cache:      69104     156032
Swap:        96384          0      96384

The first number after “-/+ buffers/cache:” is what you want. For example, from above you can see I have 224M total, ~217M is used including cache, and ~68M not counting cache.