slow (s-l-o-w) install

[Bill Davidsen]

Frank Cox wrote:
> On Sat, 16 Feb 2008 21:36:42 -0500
> Ric Moore <wayward4now at gmail.com> wrote:
> 
>> If you have 2G of memory, would using mem=2G be of any advantage?
> 
> I have 4G of memory.  It works when I specify "mem=2G".  It also works when I
> specify "mem=4024M" but I don't get a whole 4024mb.
> 
> Booting without "mem=" causes it to run amazingly slowly.
> 
I am reasonably sure that what happens is that you are using some 
uncached memory, and that is making your system slow. There are (at 
least) two possible causes, which is why I wanted the BIOS info from 
dmesg and the MTRR info.
- your BIOS could be giving bad information to the kernel
- the kernel could be generating the wrong MTRR from the BIOS info
- your hardware may not be able to cached memory mapped over 4G

OK, at least three reasons.  ;-)

In any case, that's the issue, and keeping the mem= small enough to stay 
all cached will give you vastly better performance than more slower 
memory (as you found).

-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot