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Correction on cache coherence protocols

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antoneliasson committed Oct 24, 2015
1 parent 7e14aa0 commit 691d1356a60349780cc1cffceb4fc2001e6343f4
Showing with 8 additions and 2 deletions.
  1. +8 −2 EDAN25-multicore/sammanfattningar/summary_dat11fmu.md
@@ -134,12 +134,18 @@ Cache coherence protocols
1. At a write, the cache coherence protocol should either remove all other
copies, including the memory copy, or send the newly written data to
update each copy.
- The first is called *write invalidate*
- The latter is called *write update protocol*, is almost always better
- The latter is called *write update protocol*
Which protocol is better depends on the application's sharing behavior, but
in general write invalidation is better. (ref: book pp. 175)
2. Detecting when a write has completed so that the processor can perform the
next memory access
3. Maintaining illusion of atomicity - with memory in multiple nodes the
accesses can't be atomic, but a SC machine mus behave as if they are.
accesses can't be atomic, but a SC machine must behave as if they are.
Memory access penalty
---------------------

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