Design and Verification of Adaptive Cache Coherence Protocols ...

proc proc proc
pmb mpb
pmb mpb
pmb mpb
cache cache cache
out in out in out in
network
in
out
memory
SYS Sys(MSITE, SITEs) System
MSITE Msite(MEM, IN, OUT) Memory Site
MEM [] Cell(a,v) j MEM Memory
SITEs SITE [] SITE j SITEs Set of Cache Sites
SITE Site(id , CACHE, IN, OUT, PMB, MPB, PROC) Cache Site
CACHE [] Cell(a,v,CSTATE) j CACHE Cache
IN [] MSG IN Incoming Queue
OUT [] MSG OUT Outgoing Queue
MSG Msg(src,dest,CMD,a,v) Message
CSTATE Clean [] Dirty [] CachePending [] WbPending Cache State
CMD CacheReq [] Cache [] Wb [] WbAck Command
Figure 4.2: System Con guration of Base
Message passing can happen betweenacache and the memory. A message passing rule de-
livers a message from the source's outgoing queue to the destination's incoming queue. Message
passing can be non-FIFO orFIFO. Non-FIFO message passing allows messages to be delivered
in arbitrary order, while FIFO message passing ensures messages between the same source and
destination to be received in the order in which they are issued.
Message-Cache-to-Mem Rule
Sys(Msite(mem, min, mout), Site(id , cache, cin, msg cout, pmb, mpb, proc) j sites)
if Dest(msg)=H
! Sys(Msite(mem, min msg, mout), Site(id , cache, cin, cout, pmb, mpb, proc) j sites)
Message-Mem-to-Cache Rule
Sys(Msite(mem, min, msg mout), Site(id , cache, cin, cout, pmb, mpb, proc) j sites)
if Dest(msg)=id
! Sys(Msite(mem, min, mout), Site(id , cache, cin msg, cout, pmb, mpb, proc) j sites)
Non-FIFO vs. FIFO Message Passing We use outgoing queues to model non-FIFO and
FIFO networks. Non-FIFO message passing provides no guarantee on the order in which mes-
sages are delivered. This can be e ectively characterized by allowing messages to be reordered
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