
5-15
BUS TRANSACTIONS AND OPERATIONS
5.3.2.
Transferring Snoop Responsibility
A requesting agent picks up snoop responsibility for the cache line after observing a transac-
tion’s Snoop Phase. When a requesting agent accepts snoop responsibility for a cache line and
immediately drops that responsibility in response to a subsequent transaction, it is allowed to use
the cache line exactly once for internal use, before performing an implicit writeback.
Figure 5-2 illustrates the effect of response agent responsibility pickup on an outstanding Inval-
idation Transaction (Read Invalidate Line, or an Invalidate Line Transaction). It also illustrates
that a cache line can be returned in response to an Invalidate Line Transaction if two competing
agents request ownership of a Shared cache line simultaneously.
In T1, the requesting agent P1 asserts ADS# and drives the {REQUEST} group to issue Invali-
date Request 1. In T4, a different requesting agent, P2, asserts ADS# and intends to drive the
{REQUEST} group to issue Invalidation request 2 to the same cache line. However, the snoop
of Invalidate Request 1 will invalidate the shared line in P2, forcing P2 to instead issue Read In-
validate Request 2, to the same cache line.
Figure 5-2. Response Responsibility Pickup Effect on an Outstanding Invalidation
Transaction
CLK
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3
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Содержание Pentium Pro Family
Страница 17: ...1 Component Introduction ...
Страница 26: ...2 Pentium Pro Processor Architecture Overview ...
Страница 27: ......
Страница 36: ...3 Bus Overview ...
Страница 62: ...4 Bus Protocol ...
Страница 105: ...5 Bus Transactions and Operations ...
Страница 126: ...6 Range Registers ...
Страница 131: ...7 Cache Protocol ...
Страница 135: ...8 Data Integrity ...
Страница 148: ...9 Configuration ...
Страница 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Страница 172: ...11 Electrical Specifications ...
Страница 201: ...12 GTL Interface Specification ...
Страница 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Страница 233: ...14 Thermal Specifications ...
Страница 239: ...15 Mechanical Specifications ...
Страница 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Страница 252: ...16 Tools ...
Страница 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Страница 264: ...17 OverDrive Processor Socket Specification ...
Страница 290: ...A Signals Reference ...
Страница 320: ...Index ...
Страница 328: ......