Re: x86_64 ten times slower than i386

[H. Peter Anvin]

Bo Brantén wrote:
> On Sat, 3 Nov 2007, Matt Mackall wrote:
>
> > This is typically due to a problem with the setup of your MTRRs. Try
> > booting with mem=nnnM where nnn is some number smaller than your
> > actual amount of memory.
>
> Thank you for that advice, the system has 4GB and if I boot with 
> mem=3072M it will run as fast as normal while if I don't use the mem 
> option it will run 10 times slower, however if I use a figure like 
> mem=3500M the kernel will panic, is there any way to determine the 
> highest usable figure without try and error?

Yes, look at how your MTRRs are set up (cat /proc/mtrr).

	-hpa
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