Re: [gentoo-user] necessary use flgas

[Alec Ten Harmsel <alec@alectenharmsel.com>]

On Wed, Jun 24, 2015 at 01:13:40PM +0200, Alan McKinnon wrote:
> On 23/06/2015 15:05, behrouz khosravi wrote:
> > Hello everyone.
> > 
> > I really like to have control over my machine as much as possible. In
> > this way I will learn a lot, so I am trying to remove all the default
> > use flags and control them manually.
> 
> 
> Here's some good advice:
> 
> Don't do that. See below.
> 

Nonsense - do that. If your goal is to learn how stuff works and you're
already reasonably familiar with C/C++ so you can debug any strange
errors that can happen, have fun. Just don't think you'll get any real
work done ;). i.e. it might be good to do this in a virtual machine and
still have a stable system for work.

> 
> > I just don't know which "global" use flags are absolutely necessary to
> > the system to make it snappier or secure.
> 
> That's a bit of a nonsensical line of thought, as what you think you
> want doesn't really exist.
> 
> ...
> 
> Put "-march=native" in CFLAGS
> 

Yes. Also, properly setting CPU_FLAGS_X86 is another thing that can
speed up software *if* said software supports any special instruction
sets. Most "normal desktop software" like web browsers, email clients,
terminals, editors, etc. probably will not get a whole lot of benefit
either way, since most of this software is generally not CPU-bound and
is instead network/disk bound.

In the mornings I primarily use my desktop for reading email and
browsing news with firefox (mostly on sites with minimal JavaScript),
and I have yet to see my load averages climb higher than maybe 0.5.

Any software that does anything requiring lots of math will get a boost
from this type of stuff, though; graphics editing, most things in sci-*
categories, audio/video transcoding, etc.

Alec

P.S. Just realized I don't have "-march=native" in my CFLAGS. Time to
rice - could be getting 1% better performance. ;)

P.P.S. Also, on 1% better performance: My professor for the compilers
class I took used to (maybe still does) work at Google. Apparently
Google sees a <1% increase in performance as *the best thing ever*,
because it can save them a bunch of money in infrastructure and power.
Apparently Google are the ultimate ricers.