Rebuilding Fedora

[Roland Kaeser]

Hello

I would like to thank You all for Your suggestions. But just for a small 
sample, by all arguments. Try to recomile a samba for a actual CPU 
plattform. When You run it as it comes with the dist, You will have 
around 1 MByte/second transfer performance. After recompile its around 6 
MBytes/second. The same on KDE, Apache etc. It's more than 5% Alan hmm?
But I see, we could discuss weeks about this theme. The only thing i 
need is a properly howto for recomiling the distribution. Please...

Kind regards

Roland Kaeser

Andrew Farris wrote:

>On Sun, 2004-10-24 at 21:42 +0200, Kyrre Ness Sjobak wrote:
>  
>
>>søn, 24.10.2004 kl. 21.34 skrev Andrew Farris:
>>    
>>
>>>On Sun, 2004-10-24 at 18:40 +0200, Roland Kaeser wrote:
>>>      
>>>
>>>>Hello
>>>>
>>>>There is a mistake. I would like to completly rebuild the whole 
>>>>distribution rmps from the srpms iso's not just the kernel.
>>>>
>>>>Kind regards
>>>>
>>>>Roland Kaeser
>>>>        
>>>>
>>>Are you considering the amount of cpu time required to build this entire
>>>distro?  It is not something I think you want to do on a workstation,
>>>I'd suggest rebuilding only those individual packages for apps you run
>>>constantly.  Build firefox, the KDE packages, xorg-x11, and the kernel,
>>>perhaps a very few others.
>>>
>>>If absolute optimization is your goal, go Gentoo, and experience that
>>>extra 5% Alan is talking about in his post.  I've found rebuilding i686
>>>for the constant use packages makes them 'feel' faster, but I am not
>>>positive it is more than illusion.  Rebuilding FC2 will take longer than
>>>a complete build of Gentoo.
>>>
>>>Why will it help very little?  FC already used the best possible choice
>>>of instruction order for pentium-pro and up machines, which means unless
>>>your app is going to be using SSE instructions there isn't that much
>>>more you can do.
>>>
>>>      
>>>
>>Yes, but (being anything than a compiler specialist...) can't you
>>optimize specialy for a spesific CPU, not just an arch? And how can this
>>affect loading times?
>>    
>>
>
>I'm also not a compiler specialist, but here is a general overview of
>the situation as I understand it.
>
>Yes, there are three main compiler setting choices of interest you could
>change.  What instruction set to use (march), what optimization level to
>use (Ox), and what instruction ordering to use when optimizing (mtune). 
>
>Fedora uses march for i386 machines so that the code will work on old
>hardware, but optimizes O2 (the fastest considered stable and reliable)
>and an mtune for i686 (pentium pro) so that it runs the best order of
>instructions for a i686 it can.  From there on up the architectures
>change most in ways that compiler optimizations do not capitalize on, or
>that the hardware does despite your code (some cpus actually disobey).
>You can optimize to a higher level (O3) but you see marginal gain and
>instability, or you can use higher instruction sets which will see gain
>but only for types of code that exploit the instructions (streaming
>media mostly).
>
>As for load times, you will not see excessive change in that, what
>you'll see is lower cpu usage at peak load and lower latency when
>performing more tasks at once (jerky responsiveness).
>
>Lower load times are most effected by Prelinking, so making sure that
>your system is not failing to complete the prelink is something you
>could do quickly.
>
>  
>