Re: inaccurate migration cost calculation?

[Segher Boessenkool]

> Across different boots using the same 2.6.19 kernel on a quad-core xeon
> I see huge variance in the migration_cost being reported during boot.
>
> -migration_cost=39,3940
> +migration_cost=25,4941
>
> This CPU has a very large cache which could be key here...
>  L1 Instruction cache: 32KB, 8-way associative. 64 byte line size.
>  L1 Data cache: 32KB, 8-way associative. 64 byte line size.
>  L3 unified cache: 4MB, 16-way associative. 64 byte line size.

That last cache is shared between CPU cores, which leads
to big non-determinism -- not sure if there's much you can
do about it.


Segher

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