Fujitsu Fujitsu SPARC64 V manual Cache Coherency Protocols, Cache Control/Status Instructions

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TABLE M-4

M.2 Cache Coherency Protocols

The CPU uses the UPA MOESI cache-coherence protocol; these letters are acronyms for cache line states as follows:

M

Exclusive modified

O

Shared modified (owned)

E

Exclusive clean

SShared clean

I Invalid

A subset of the MOESI protocol the system controller.

is used in the on-chip caches as well as the D-Tags in shows the relationships between the protocols.

TABLE M-4Relationships Between Cache Coherency Protocols

L2-Cache

L1D-Cache

SAT (store ownership)

L1I-Cache

 

 

 

 

Invalid (I)

Invalid (I)

Invalid (I)

Invalid (I)

Shared Clean (S)

 

 

 

Shared Modified (O)

Invalid (I) or Clean (C)

Invalid (I)

Invalid (I) or

Exclusive Clean (E)

 

 

 

Valid (V)

Exclusive Modified (M)

Invalid (I)

 

 

 

Exclusive Modified (M)

Valid (V)

 

 

 

TABLE M-5shows the encoding of the MOESI states in the L2 Cache.

TABLE M-5L2 Cache MOESI States

 

Bit 2 (Valid)

Bit 1 (Exclusive)

Bit 0 (Modified)

State

 

0

Invalid (I)

 

1

0

0

Shared clean (S)

 

1

1

0

Exclusive clean (E)

 

1

0

1

Shared modified (O)

 

1

1

1

Exclusive modified (M)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

M.3 Cache Control/Status Instructions

Several ASI instructions are defined to manipulate the caches. The following conventions are common to all of the load and store alternate instructions defined in this section:

128 SPARC JPS1 Implementation Supplement: Fujitsu SPARC64 V • Release 1.0, 1 July 2002

Page 139
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Fujitsu Fujitsu SPARC64 V Cache Coherency Protocols, Cache Control/Status Instructions, Table M-5L2 Cache Moesi States