[Beowulf] Optimal BIOS settings for Tyan K8SRE
hahn at physics.mcmaster.ca
Sun Sep 3 19:06:26 EDT 2006
> 270s) which are being used primarily for Oceanographic modelling (MPICH2
> running on Debian/Linux 2.6 kernel).
> I had to make some tweaks to make all 4GB of RAM visible to the OS.
how much was missing, and was it just graphics aperture-related?
> HT-LDT Frequency Auto
> Dual-Core Enable Enabled
> ECC Features
> ECC Enabled
> ECC Scrub Redirection Enabled
> Dram ECC Scrub CTL Disabled
> Chip-Kill Disabled
> DCACHE ECC Scrub CTL Disabled
> L2 ECC Scrub CTL Disabled
those seem to be normal settings I see on most machines. the RAS-related
settings seem to be unnecessary for a "normal" cluster (one where no large
rate of ECC's happen, and one where a reboot doesn't cause planes to fall
out of the sky.)
on the other hand, I'd love to find out whether there is any performance
impact from enabling scrub, since it does slightly increase memory workload.
then again, if your rate of correctable ECCs is trivial, scrubbing is not
> Memory Hole
> 4GB Memory Hole Adjust Manual
> 4GB Memory Hole Size 768 MB
> IOMMU Enabled
> Size 32 MB
> Memhole mapping Hardware
I don't think there are performance implications here. you seem to have
already found the right combination of iommu/memhole settings that give
you your full roster of ram. my googling on the topic didn't enlighten
me much, though people apparently recommend "iommu=memaper=3"
> Memory Config
> Swizzle Memory Banks Enabled
donno - I don't think this appears in the AMD bios-writers guide
> DDR clock jitter Disabled
> DDR Data Transfer Rate Auto
> Enable all memory clocks Populated
> Controller config mode Auto
> Timing config mode Auto
those are the settings I normally see as well.
> AMD PowerNow! Disabled
> Node Memory Interleave Auto
> Dram Bank Interleave Auto
for numa-aware OS's (like any modern linux), I think node-memory
interleave should be disabled.
regards, mark hahn.
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