amd64 slower than i386 on identical AMD 64 system?

JoaoBR joao at
Fri Mar 17 12:10:11 UTC 2006

On Friday 17 March 2006 02:48, Martin Nilsson wrote:
> JoaoBR wrote:
> > with 2GB no problem,
> >  3GB I do not know but 4GB is when the problem appears here for me
> >
> >> Wonder if there is some sort of memory pairing issue. To get >2GB and
> >> <4GB I'd think you have to have 2 1GB sticks and 2 512MB sticks or
> >> something like that.
> >
> > no it isn't in my case, I use real good dual-channel 2x (2x1GB) 
> > suggested memory listed in the MB manual
> With 4GB memory you will likely get some memory remapped above 4GB,
> could your problems be caused by a buggy driver that doesn't support
> memory over the 4GB barrier correctly? (The ata driver comes to mind)
I thought this at the beginning, I got an answer from Asus and Epox support 
that the never Bios versions prevent this since the southbridge on Asus as 
example cuts some 300Mb already so I have this when using 4GB
real memory  = 3992649728 (3807 MB)
avail memory = 3858542592 (3679 MB)

there are also some rumors on some mailling lists that when using 4 double 
density DDR400 ram modules that the MB only recognizes them as DDR333 what I 
did not get confirmed anywhere, neither Asus nor Epox, that appearently has 
to do when people use not full qualified modules only
there may be an issue using double density modules regarding dualchannel but 
the worse case that the memory module is not working as dual channel and the 
board should work normally. 

well, I do not use IDEs or SATAs and it seems the ahd driver is not affected
I have a very small kernel and I do not even compile sio/lpt or any other 
unecessary stuff
I use xl|sk|nve and the scsi driver only

I just compiled a releng_6 i386  and will check this weekend one of this X2 
machines to see what happens


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