Re: any reasons to recompile kernel?

On 22 Jul 2005, at 06:13, Maurice Ling wrote:
>>> I have 2 systems, G4 1GHz and G4 733MHz. I am under the  
>>> assumption  that using Tiger on my "old" machines will just slow  
>>> it down.
>>
>> You must be a Windows user to get to that conclusion. Ever since  
>> Mac  OS X's Public Beta, each newer version was less CPU and  
>> memory hungry.
>>
>> Same for Tiger. They manage somehow to fill no less than 5 GB with  
>> OS  + DevTools on disk. This is 50% more over Panther, but the GUI  
>> is  again snappier. RAM usage is more efficient, swap files are  
>> smaller.  I'm using a 500 MHz G3 iBook.
>
> I do agree that my assumption is based on Windows-land.  
> Nevertheless, I've only been a Mac user for 2 years and I am glad  
> that I chose it for my develop work. At the same time, I am also  
> affected by Linux-land where a good portion of system optimization  
> has to do with kernel recompilation.

Bingo. On linux, there are thousands of things that you change just  
by configuring your kernel, none of which have anything to do with  
changing the source code. On Mac OS X and Darwin, there's no reason  
at all to recompile the kernel unless you're changing code (and even  
then, you should do a kernel extension).

You may have heard that Darwin uses the mach microkernel. This means  
that the core kernel is extremely simple and small (compared to  
linux). On top of that is most of the FreeBSD Kernel. This does not  
have anywhere near as many configuration options as Linux, and most  
simply do not apply to XNU because many of the most configurable  
components (like the driver architecture) are not imported from  
FreeBSD, but specific to XNU (i.e. IOKit). Basically, this leaves  
almost no configuration options to someone looking to recompile.  
There are a few in the BSD layer, but they're already tuned by Apple  
and so don't need any changing.

Hope this helps,
JP



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