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SubjectRe: BFS vs. mainline scheduler benchmarks and measurements
On 09/09/2009 02:20 AM, Jiri Kosina wrote:
> On Wed, 9 Sep 2009, Nikos Chantziaras wrote:
>
>>>> Here the result:
>>>>
>>>> http://foss.math.aegean.gr/~realnc/pics/latop2.png
>>>>
>>>> Again: this is on an Intel Core 2 Duo CPU.
>>>
>>> Just an idea: Maybe some system management code hits you?
>>
>> I'm not sure what is meant with "system management code."
>
> System management interrupt happens when firmware/BIOS/HW-debugger is
> executed in privilege mode so high, that even OS can't do anything about
> that.
>
> It is used in many situations, such as
>
> - memory errors
> - ACPI (mostly fan control)
> - TPM
>
> OS has small to none possibility to influence SMI/SMM. But if this would
> be the cause, you should probably obtain completely different results on
> different hardware configuration (as it is likely to have completely
> different SMM behavior).

Wouldn't that mean that a BFS-patched kernel would suffer from this too?

In any case, of the above, only fan control is active, and I've run with
it disabled on occasion (hot summer days, I wanted to just keep it max
with no fan control) with no change. As far as I can tell, the Asus P5E
doesn't have a TPM (the "Deluxe" and "VM" models seem to have one.) As
for memory errors, I use unbuffered non-ECC RAM which passes a
memtest86+ cycle cleanly (well, at least the last time I ran it through
one, a few months ago.)


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