mem: Clarification of packet crossbar timings

This patch clarifies the packet timings annotated
when going through a crossbar.

The old 'firstWordDelay' is replaced by 'headerDelay' that represents
the delay associated to the delivery of the header of the packet.

The old 'lastWordDelay' is replaced by 'payloadDelay' that represents
the delay needed to processing the payload of the packet.

For now the uses and values remain identical. However, going forward
the payloadDelay will be additive, and not include the
headerDelay. Follow-on patches will make the headerDelay capture the
pipeline latency incurred in the crossbar, whereas the payloadDelay
will capture the additional serialisation delay.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mem/xbar.hh b/src/mem/xbar.hh
index 6e7d7afce..81b16c19d 100644
--- a/src/mem/xbar.hh
+++ b/src/mem/xbar.hh
@@ -333,9 +333,9 @@ class BaseXBar : public MemObject
 
     /**
      * Calculate the timing parameters for the packet. Updates the
-     * firstWordDelay and lastWordDelay fields of the packet
+     * headerDelay and payloadDelay fields of the packet
      * object with the relative number of ticks required to transmit
-     * the header and the first word, and the last word, respectively.
+     * the header and the payload, respectively.
      */
     void calcPacketTiming(PacketPtr pkt);