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by j_seigh
75 days ago
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My impression was LL/SC had forward progress issues due to the difficulties of preventing false sharing of the locked memory reservation region. Updates into that region would keep invalidating the lock. I had a version of atomic* reference counting that used LL/SC on a ppc mac mini along side x86 versions using cmpxchg16b. Code used to be sourceforge before it went to the dark side. An early posting of the idea before I got around to implementing it.
https://groups.google.com/g/comp.programming.threads/c/HZqn5... * Std::shared_ptr and Rust ARC aren't actually atomic. You have to own a reference to do a copy. The are what POSIX calls thread-safe. With atomic reference counting, if you copy a reference, you either get a valid reference or null. Like Java references. |
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