physical memory support under RHEL for Opteron
Joshua Baker-LePain
jlb17 at duke.edu
Wed Mar 31 17:12:03 UTC 2004
On Wed, 31 Mar 2004 at 12:00pm, redhat-list-request at redhat.com wrote
> I am just about to order an dual Opteron 248 server to run under RHEL AS.
>
> I would like to double check the physical memory supported - we are getting
> 8 x 2GB PC3200 or PC2700 memory on this server.
>
> I have found something a bit obscure on the RH web page:
> http://www.redhat.com/software/rhel/as/
> <http://www.redhat.com/software/rhel/as/>
>
> in that it said:
>
> ** 64GB is the maximum memory size for X86 systems. Maximum memory sizes
> vary with other architectures.
>
> Can anyone confirm
> a. the maximum memory size for Opterons supported, and
> b. the maximum usable physical memory per process on user applications
>From /usr/src/linux-2.4.21-9.EL/Documentation/x86_64/mm.txt on my RHEL3.0
AMD64 system:
The paging design used on the x86-64 linux kernel port in 2.4.x provides:
o per process virtual address space limit of 512 Gigabytes
o top of userspace stack located at address 0x0000007fffffffff
o start of the kernel mapping = 0x0000010000000000
o global RAM per system 508*512GB=254 Terabytes
o no need of any common code change
o 512GB of vmalloc/ioremap space
So I think you're OK with 16GB. ;) FWIW, that systems has 8GB and runs
wonderfully. Be sure to follow the recommendations in bugs 118152 and
115438, which fix a couple of memory issues.
--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University
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