information to keep in registers and which to keep in main memory 2 Hardware

Information to keep in registers and which to keep in

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information to keep in registers and which to keep in main memory. 2. Hardware-only caches: caches that are implemented totally in HW. Most systems have an instructions expected to be executed. This type is outside of the control of the operating system.
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Coherency and ConsistencyIn a hierarchical storage structure, the same data may appear in different levels of the storage system. For example, consider an integer A located in the file B resides on magnetic disk that is to be incremented by 1: 1. Issue an I/O operation to copy the disk block on which A resides to main memory. 2. Copy A to the cache, and by a copying of A to an internal register. 3. The increment takes place in the internal register. 4. The new value of A is written back to the magnetic disk. The copy of A appears in several places.
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Coherency and ConsistencyCache coherency problem occurs in multiprocessor environment where a copy of A may exist simultaneously in several caches. It is a hardware issue. In distributed environment, the situation becomes more complex. Several copies of the same file can be kept on different computers that are distributed in space. Whenever a processor modifies a data block in its cache, the copies of the same data block in other caches and the memory are not updated. So, the other caches would have the old copy of the same data block. This leads to data inconsistency and it’s a cache coherence problem.Whenever a processor modifies a data block in its cache, the copies of the same data block in other caches and the memory are not updated. So, the other caches would have the old copy of the same data block. This leads to data inconsistency and it’s a cache coherence problem.
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Coherency and Consistency
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Coherency and Consistency
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