[Beowulf] Optimal BIOS settings for Tyan K8SRE

[Eric W. Biederman]

stephen mulcahy <smulcahy at aplpi.com> writes:

> Hi Bruce,
>
> Do you have any idea what the performance impact from enabling scrubbing
> is on your systems? did you do any before/after benchmarking?

I don't know what the performance impact of scrubbing is for Bruce.  I
did some looking a long time ago on Opterons and at the Highest
frequency the scrubbing consumed 50% of the memory bandwidth, at the
lowest frequency you couldn't measure that it was turned on.

Enabling ECC and chipkill ECC has no measurable impact.

What chipkill buys you is the reasonable assurance that if you
have a long uptime and you get soft memory errors something will
look at and correct the data before multiple errors have time to
accumulate.

For performance I suspect you will see much more variation depending
on the speed of memory in your system.

Eric