Re: [PATCH] Radix-tree pagecache for 2.5

From: David S. Miller (davem@redhat.com)
Date: Fri Feb 01 2002 - 04:10:10 EST


   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.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Thu Feb 07 2002 - 21:00:12 EST