2:536
Volume 2, Part 2: MP Coherence and Synchronization
Finally, software may also eliminate the
mf
or
srlz.i
instructions if it
guarantees
that
these operations will take place elsewhere (e.g. in the operating system) before the
processor attempts to execute the updated code. For example, context switch routines
must contain a memory fence (see
). Thus, the fence is
not required if a context switch
always
occurs before any program can use the updated
code.
2.5.4
DMA
Unlike Programmed I/O, which requires intervention from the CPU to move data from
the device to main memory, data movement in DMA occurs without help from the CPU.
A processor based on the Itanium architecture expects the platform to maintain
coherency for DMA traffic. That is, the platform issues snoop cycles on the bus to
invalidate cacheable pages that a DMA access modifies. These snoop cycles invalidate
the appropriate lines in both instruction and data caches and thus maintain coherency.
This behavior allows an operating system to page code pages without taking explicit
actions to ensure coherency.
Software must maintain coherency for DMA traffic through explicit action if the platform
does not maintain coherency for this traffic. Software can provide coherency by using
the flush cache instruction,
fc
, to invalidate the instruction and data cache lines that a
DMA transfer modifies. Code such as that shown in
accomplish this task.
2.6
References
[AG95] S. V. Adve and K. Gharachorloo. “Shared memory consistency models: A
Tutorial,” Rice University ECE Technical Report 9512, September 1995.
[L79]
L. Lamport. “How to make a multiprocessor computer that correctly executes
multiprocess programs,”
IEEE Transactions on Computers
, C-28(9):690-691,
September 1979.
[HP96] J. L. Hennessy and D. A. Patterson.
Computer Architecture: A Quantitative
Approach
, second edition, Morgan-Kaufmann, 1996.
[D65] E. W. Dijkstra. “Cooperating sequential processes,” Eindhoven, the Netherlands,
Technological University Technical Report EWD-123, 1965.
[L85]
L. Lamport. “A Fast Mutual Exclusion Algorithm,” Compaq Systems Research
Center Technical Report 7, November 1985.
§
Summary of Contents for ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Page 1: ......
Page 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Page 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Page 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Page 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Page 230: ......
Page 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Page 380: ...2 132 Volume 2 Part 1 Interruptions ...
Page 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Page 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Page 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Page 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Page 808: ...2 560 Volume 2 Part 2 Context Management ...
Page 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Page 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Page 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Page 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Page 891: ......
Page 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Page 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Page 1296: ......
Page 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...