slow (s-l-o-w) install

Chris Snook csnook at
Thu Feb 21 20:38:01 UTC 2008

Frank Cox wrote:
> On Sat, 16 Feb 2008 17:41:04 -0500
> Bill Davidsen <davidsen at> wrote:
>> I don't think the install will run a bit faster for using more memory, 
>> while it will run tons slower if you don't run cache. Since this is a 
>> one-time thing during install, I don't see any reason to avoid it.
> I tried installing again, specifying "mem=2G", and it zipped right along.  Now
> I have a working machine that runs fine as long as I specify a "mem=" amount.
>  However,  having specified "mem=4024M" in my grub.conf, I
> actually ended up with this:
> [frankcox at mutt ~]$ free
>              total       used       free     shared    buffers     cached
> Mem:       3342416     702628    2639788          0      16480     289760
> -/+ buffers/cache:     396388    2946028
> Swap:      2031608          0    2031608
> I have more ram now than I did with "mem=2G" but I seem to have lost 760mb;
> 4024-3264=760.
>> After 
>> install you can look at MTRR adjustments to allow all 4GB during normal 
>> operation.
> How would I go about making these adjustments and what adjustments should I be
> making?  (I know absolutely nothing about MTRR.)
> Here is what I've got now:
> reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
> reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
> reg02: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1
> reg03: base=0xcf800000 (3320MB), size=   8MB: uncachable, count=1
> reg04: base=0xcf400000 (3316MB), size=   4MB: uncachable, count=1
> reg05: base=0x100000000 (4096MB), size= 512MB: write-back, count=1
> reg06: base=0x120000000 (4608MB), size= 128MB: write-back, count=1
> reg07: base=0xd0000000 (3328MB), size= 256MB: write-combining, count=1

That looks a bit odd.  I can't swear it's wrong, but it's odd.

> What changes should I be looking at making, and how do I go about making them?

Can you change how your BIOS handles memory hole remapping?  Mine has the option 
of using either discrete or continuous mapping, and they don't generate 
semantically equivalent mtrr configurations.  Switching this option made a 4G 
problem go away for me.

	-- Chris

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