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Date: Fri, 01 Feb 2002 01:10:10 -0800 (PST)
Message-Id: <20020201.011010.45741509.davem@redhat.com>
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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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