Messages in this thread | | | From | Segher Boessenkool <> | Subject | Re: inaccurate migration cost calculation? | Date | Wed, 3 Jan 2007 19:33:52 +0100 |
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> 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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