Yo there, I whish to hear some suggestions about fine tunning linux [I mean get the most of the hardware in terms of speed].
Im speaking of a machine amd athlon x2 @ 2.2 Ghz and 512 Mb and a Turion 64 @ 2Ghz with 4 Gb.
Both are intended to coding, electronics simulation, tex writing and virtualization.

Thanks in advance!!!

I don't know much about any advanced linux tuning, but there are a few simple steps to increase the performance of your linux:

1. Get a lightweight desktop environment (xfce, fluxbox, etc)
2. Switch off all the unnecessary services.
3. Install a 64bit linux on your 4gb box (a 32bit version can recognise only slightly over 3gb of your RAM. There are PAE kernels, but AFAIK, the performance is better on a true 64 bit system.)

4. You might also read something about real-time kernels. I don't know much about them and am not sure how they affect performance in terms of speed.

1 & 2 above are probably the best suggestions that could be made (although I'm not really sure how much the lightweight UI helps, once you have ample amounts of ram).

There was another thread asking about the performance loss with PAE, but so far, the poster hasn't received any quantitaive data ((bah! update: look here http://www.linuxquestions.org/questi...ce-hit-723652/ for suspicions of numerical data). I suspect (over a non-pae 32 bit system) it isn't much, but I don't know. 64 bit has advantages and disadvantages, and I think, in most cases, the balance is for a rather modest advantage, but it depends somewhat on what testing you do. Maybe the phorons over at phoronix have something for you.

Unfortunately, real time has two meanings. The one that is most relevant in this context is as in Redhat/SuSE for fast database access. As this is essentially a rebalancing of scheduler behaviour, I think I can be sure that this is very dependant upon loading and the test employed and is advantageous for the intended application, but as nothing is clear about the OPs intended application, I can say no more (and probably could not say much more, even if I did know more about the application).

Oh, turn off 'atime', adjust swappiness if that's what floats your boat (probably you can make your system feel more responsive in the normal case, at the expense of degraded response in overload situations), look at mount options for journalling filesystems to check that they are what you want (defaults for the safety:speed tradeoff differ among distros) and think about wheteher the filesystem types and partitioning types are right for your workload.

...got distracted...

and if some of this is networking performance, consider, in particular, name resolution performance (should you be caching look ups in some way?) and maybe squid as a proxy server (although, I've been a bit underwhelmed by the speed gains from squid, but then there are other advantages too, and you need to do a bit of config to get the best out of it).

Of course, these are pre-canned reccomendations for some kind of imagined situation; it would be far better if we knew what was slow, what the data was on your particular situation and what was and wasn't running well and what is and isn't causing you problems, backed up with data.

First thanks for the reply:Salasi and Sycamorex. You are great gurus of this business.
By the way the enviroment of these machines arent to acces a wide range of users , its me and perhaps 2 or 3, so the network delays arent so much concern. Im a bit more in terms of volume transfer in my own partitions. I ve alywas used ext3 fs and given the swap gigs instead of megs [dunno if this is good or bad].
Im checking the PAE data, because of the magic I ll try to do, im focused towards the 64 bities, [My boss is a freak and tell me its more sharp and acute to use it =)!].
Im testing it and post my results here. Stay tuned!!!

I'd definitely add more RAM to the Athlon. The more of your stuff you can get in RAM the faster it'll feel.

Compile a kernel for your architecture, plus other options, see here Chapter 7 mostly:
http://www.kroah.com/lkn/

What distro are you using ?

You can also try other filesystems such as JFS, XFS for possible improved performance in some areas.

Plus the stuff said above:
avoid KDE, GNOME, even XFCE
turn off start up programs

Thanks chrism01 and H_TeXMeX_H , you are very kind men.!!!!=)!
unfortunately I only have 512mb modules. and the brakets of the slots are broken =(!!! [ideas to fix it are welcome!!!] and Im cheking the kernel to recompile right now!!!
Thanks. Expect results!!!