Service manual

B-34 AlphaServer GS80/160/320 Service Manual
B.10.6 Global (Remote) Change-to-Dirty Transactions
Figure B– 11 Change-to-Dirty Coherency Store Flow
Q0: Visit Dtag
via ArBus
Visit TTT
via GPLink.
Q0
Q0Vic
Q1
Q1
Response
Packet
Q1
Probe
Packet
(Inval)
Q1: Visit TTT,
Dtag and IOP
Tag store, via
ArbBus.
Source QBB
Q0: Visit Directrory
Dtag, TTT and
IOP Tag store
via ArbBus.
Home QBB
Q1: V isit Dtag, TTT and
IOP Tag store
via ArbBus.
QBB of Shared Processor
Remote Change-to-Dirty, Shared-to-Dirty and STCChange-to-Dirty commands
use the system coherency storage elements as illustrated in Figure B–11 and
described by the following sequence of events.
1. Each Change-to-Dirty-type command is first issued to the ArbBus of the
requesting processors QBB. It visits the DTag to determine if it should fail
locally or propagate to its home directory.
2. All Change-to-Dirty-type commands that do not fail in the DTag then visit
their local TTT via the GPLink, to create a TTT MAF entry.