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unify ruby and cache coherency a bit more

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Ciro Santilli 六四事件 法轮功
2020-03-06 00:00:01 +00:00
parent 281455fe13
commit d934dccecb
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@@ -12466,11 +12466,11 @@ gem5 has two types of memory system:
* the classic memory system, which is used by default
* the Ruby memory system
The Ruby memory system includes the SLICC domain specific language to describe memory systems: http://gem5.org/Ruby SLICC transpiles to C++.
The Ruby memory system includes the SLICC domain specific language to describe memory systems: http://gem5.org/Ruby SLICC transpiles to C++ auto-generated files under `build/<isa>/mem/ruby/protocol/`.
Ruby seems to have usage outside of gem5, but the naming overload with the link:https://en.wikipedia.org/wiki/Ruby_(programming_language)[Ruby programming language], which also has link:https://thoughtbot.com/blog/writing-a-domain-specific-language-in-ruby[domain specific languages] as a concept, makes it impossible to google anything about it!
Since it is not the default, Ruby is generally less stable that the classic memory model. However, because it allows describing a wide variety of important coherency protocols, while the classic system only describes a single protocol, Ruby is very importanonly describes a single protocol, Ruby is a very important feature of gem5.
Since it is not the default, Ruby is generally less stable that the classic memory model. However, because it allows describing a wide variety of important <<cache-coherence,cache coherency protocols>>, while the classic system only describes a single protocol, Ruby is very importanonly describes a single protocol, Ruby is a very important feature of gem5.
Ruby support must be enabled at compile time with the `scons PROTOCOL=` flag, which compiles support for the desired memory system type.
@@ -12484,10 +12484,10 @@ and therefore ARM already compiles `MOESI_CMP_directory` by default.
Then, with `fs.py` and `se.py`, you can choose to use either the classic or built-in ruby system at runtime with the `--ruby` option:
* if `--ruby` is given, use the ruby memory system that was compiled into gem5
* otherwise, use the classic memory system
* if `--ruby` is given, use the ruby memory system that was compiled into gem5. Caches are always present when Ruby is used, since the main goal of Ruby is to specify the cache coherence protocol, and it therefore hardcodes cache hierarchies.
* otherwise, use the classic memory system. Caches may be optional for certain CPU types and are enabled with `--caches`.
For example, to use a two level https://en.wikipedia.org/wiki/MESI_protocol[MESI] https://en.wikipedia.org/wiki/Cache_coherence[cache coherence protocol], we can do:
For example, to use a two level <<mesi-protocol>> we can do:
....
./build-gem5 --arch aarch64 --gem5-build-id ruby -- PROTOCOL=MESI_Two_Level