Sun Microsystems UltraSPARC-I - Interconnect Packet Formats

Sun Microelectronics
138
UltraSPARC User’s Manual
7.16.12 ReadToOwn Dirty Victimized Block
Condition: Store hit by another processor (P2).
The following transaction sequence is the same as for Section 7.16.5, “Read-
ToOwn Block,” except that P2 already has the block in the Shared state (store hit),
and P1 has the victimized block in the Owned state (due to the previous Read-
ToShare request from P2).
7.17 Interconnect Packet Formats
This section specifies the packet formats for the Interconnect transaction set. The
transaction request packets are carried over SYSADDR.
Table 7-36 Copyback-Invalidate Dirty Victimized Block in Owned State
Processor 1 System Processor 2 Processor 3
Initial victim state:
Etag1{O}
Initial missed state:
Etag2{I}
P1 copies the victimized block into the
writeback buffer}
P_RDS_REQ to System
(DVP bit set)
Initial state:
Etag1{S}
Initial state:
Etag2{I}
Initial state:
Etag2{I}
S_RBU reply to P1
P1 reads data
updates Etag2{I → E}
P_RDO_REQ to System for
victim block in P1.
S_INV_REQ to P1
P_SACKD to System
S_OAK reply to P2
(no data transfer)
P2 updates Etag1{S → M}
P_WRB_REQ to System serviced now
S_WBCAN reply to P1
P1 clears writeback buffer tag
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