Difference between i386 and i686
 

I am running RH 9

I have a simple question about the difference between i386 and i686. This is about differences in CPU speed and the necessary kernel to fully utilize those differences, right? I can run my computer using i686 according to RHs website, but I have the other installed. Is the only difference the kernel? I dont have to fully reinstall the i686 version if I want to maximize the power of my CPU, do I? Just a simple question.

Thanks!

hajimemashite.

in my experience, recompiling your kernel for i686 will make the
biggest difference. installing all packages for i686 instead of i386
will improve performance a bit too for those packages, but it will
not have as big an impact as the kernel recompile.

good luck.

Re: Difference between i386 and i686
 

Yes, you do. The 386 processor architecture can be seen as a subset of 686 architecture. Especially as the machine command list. The internal machine instruction cashing method, pipelining, parallel command execution etc. are different. The same program can run faster if it is compiled (optimized) for a target processor. So although you do not change the power of the CPU itself you can change the the power of the application.

Thanks for the scoop! Since I am just a beginner, I might wait a bit before trying to recompile the kernel.... I did do some programming in college though, and I am wondering if compiling a new Kernel is just as easy as using a compiler along with the correct source code. That is, I dont have to literally look into the code and alter any of that, do I?

um, compiling the kernel really couldn't be easier. You don't have to do anything manually, and you have a nice menu interface (or an X11 one if you go that way)
All you need to do is go to /usr/src/linux and type make xconfig (if you're running a graphical env - menuconfig if you're just on a text console)
set all your options in there - making sure to include all your device drivers and file systems you want. then do:
make clean
make dep && make modules bzImage
make modules_install
then you copy the bzImage to the /boot directory and add it into your boot loader.
I have all my programs (everything) compiled for athlon-xp which means it will do sse and mmx and 3dnow2, which helps a bit with some apps. I have the kernel compiled for i686 though as compiling for athlon (or pentuim 4) causes problems with modules and unresolved symbols.

Well for clarity and with as much brevity as possible:

1) I need to download the new kernel.

2) I then run make xconfig in the mentioned directory, having first moved the new kernel file there? or I unpack the new kernel in that directory and then run xconfig?

3) I configure everything and then make clean, etc.

4) Finally when I add this to the boot loader, what exactly am I doing? Do I add a line to the boot loader that ... points (if that is the right term) to this new file?

Well, if you have time to reply, please let me know. I will look into it myself nonetheless.

Thanks:)

You don't need to download a new kernel, unless you particularly want the latest version. If you download one from kernel.org, it will be missing a few features added by Redhat, and you might get some od behaviour.

There's lots of detailed HOWTOs on the net about compiling the kernel, so you'll probably get better information from them than you will here.

Alex

Thanks Alex. I will look into it.