Re: inaccurate migration cost calculation?
From: Segher Boessenkool
Date: Wed Jan 03 2007 - 13:33:49 EST
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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