Gentoo Forums
Gentoo Forums
Gentoo Forums
Quick Search: in
Gentoo-sources kernel oddities
View unanswered posts
View posts from last 24 hours

 
Reply to topic    Gentoo Forums Forum Index Portage & Programming
View previous topic :: View next topic  
Author Message
geoffs
n00b
n00b


Joined: 15 Feb 2003
Posts: 35
Location: Canada

PostPosted: Mon Mar 03, 2003 8:51 am    Post subject: Gentoo-sources kernel oddities Reply with quote

I decided to give the gentoo sources kernel a go today. Everything went ok (i guess) and when it was all said and done I noticed 2 strange things.

The gentoo-sources kernel is about 100k bigger then my old 2.4.20 vanilla kernel (same config)... AND my system lost 25 bogomips with the gentoo-sources kernel. Now 25 bogomips might not sound like a lot, but I find it odd that the "optimized" kernel would have this effect.

My machine is a dual celeron system...does SMP have anything to do with this?
_________________
CAT
Back to top
View user's profile Send private message
geoffs
n00b
n00b


Joined: 15 Feb 2003
Posts: 35
Location: Canada

PostPosted: Thu Mar 06, 2003 5:32 am    Post subject: Reply with quote

ttt

someone else must have this problem
_________________
CAT
Back to top
View user's profile Send private message
max_colby
Tux's lil' helper
Tux's lil' helper


Joined: 30 Nov 2002
Posts: 149
Location: Ottawa, Canada

PostPosted: Thu Mar 06, 2003 6:28 am    Post subject: Reply with quote

Gentoo sources compiles itself with -O3 while all other kernels I've tried compiled with -O2. That explains the increased code size (due to code inlining).

As for lost bogomips, some patches slightly decrease the peak performance of certain things in favour of responsiveness and a faster 'feel', since many of the patches are aimed at desktop users.

Also, most of what I've read, and my own experience has supported that -O2 creates faster code than -O3, so this might have something to do with it; I'm not sure about the kernel compilation specifically though. I'm not sure how to get gentoo-sources to compile at a lower level either .. hopefully somebody can fill me in.
Back to top
View user's profile Send private message
max_colby
Tux's lil' helper
Tux's lil' helper


Joined: 30 Nov 2002
Posts: 149
Location: Ottawa, Canada

PostPosted: Thu Mar 06, 2003 6:46 am    Post subject: Reply with quote

As for changing the kernel compilation options, this has come up in another thread:
http://forums.gentoo.org/viewtopic.php?t=5717&start=325

All you have to do is edit line 20 of the kernel Makefile
Code:
nano /usr/src/linux/Makefile -w


I really wouldn't recommend changing anything other than the -O* value though
Back to top
View user's profile Send private message
Display posts from previous:   
Reply to topic    Gentoo Forums Forum Index Portage & Programming All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum