A method and apparatus for a cache line cut through reduces the latency
and memory bandwidth of a data processing system. By cutting through or
forwarding a cache line to the next processing element, data that has
been read from a local memory into a local cache and altered by a
processing element need not be restored to the local memory before it is
sent to its destination target processing element. By eliminating the
write back to the local memory for direct write through to the
destination, performance is increased because the bandwidth and latency
are decreased. In a preferred embodiment, the processing elements may be
contained within a network processor and the altered data may be a header
in one network protocol which needs to be modified to another protocol
before transfer of the data along the network. Transfer of the data may
be to another network processor, another processing element, or to
another memory.