Sun Microsystems UltraSPARC-I User Manual page 151

raSPARC User's Manual
Table 7-33 Victim Writeback: Writeback Serviced Before Read Miss
Processor 1
P1 reads the data
updates Etag2{I
16.10 ReadToShare Dirty Victimized Block
Condition: Load miss by another processor (P2) on a dirty line for which Proces-
sor 1's Writeback transaction has not yet completed.
The following transaction sequence is the same as is Section 7.16.8, "Victim Write-
back," except that another processor (P2) makes a ReadToShare request for the
victimized block in P1 before SC has acknowledged P1's Writeback transaction.
Table 7-34 Copyback Dirty Victimized Block
Processor 1
ial victim state:
g1{M}
ial missed state:
g2{I}
copies the victimized block into the
teback buffer}
RDS_REQ to System
VP bit set)
reads the data,
dates Etag2{I E}
makes another copy of the victim
ck into the copyback buffer
SACKD or P_SACK reply to System
WRB_REQ to System
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System
Start read from memory
S_RBU reply to P1
E}
System
S_RBU reply to P1
S_CPB_REQ to P1
S_CRAB reply to P1
S_RBS reply to P2
S_WAB reply to P1
Processor 2
Final state:
No change
Processor 2
Initial state: Initial state:
Etag1{I} Etag2{I}
Initial state:
Etag2{I}
P_RDS_REQ to System
for the victim block in P1
P2 reads data and
updates Etag1{I S}
Processor 3
Final state:
No change
Processor 3