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SubjectRe: [PATCH] Radix-tree pagecache for 2.5
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   From: Momchil Velikov <velco@fadata.bg>
Date: 01 Feb 2002 11:01:50 +0200

Does cache line bounce (shared somewhere -> exclusive elsewhere) cost
more that a simple miss (present nowhere -> exclusive somewhere) ?

They are about equal. For coherency purposes all cpus have to listen
to all the transactions anyways to see if they have a match in their
L2 caches (and thus must provide the data to the requestor).

Perhaps the exclusive somewhere --> exclusive somewhere else is a bit
more expensive because you eat a write port for the cache line move on
the processor providing the data.
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