4 ms·

Hmm.. why bother with a complicated approach now that transactional memory (Intel TSX) is available in HW now? What are the advantages and disadvantages of this

by zvrba 10y ago

Hmm.. why bother with a complicated approach now that transactional memory (Intel TSX) is available in HW now? What are the advantages and disadvantages of this approach vs using TSX?

karmicthreat 10y ago
Because the TSX feature isn't stable and Intel is still disabling it in some recent processors.
- zvrba 10y ago
  Not "recent". It's disabled in Haswell where it debuted, but it's OK from Broadwell on. From wikipedia, with citation: The bug was fixed in F-0 steppings of the vPro-enabled Core M-5Y70 Broadwell CPU in November 2014.[22] We're talking about end of 2014.
hendzen 10y ago
Hardware transactions as implemented by TSX are not wait free. There is no guarantee that any TSX transaction will ever commit, so you need a non-transactional fallback path to guarantee forward progress.
- zvrba 10y ago
  Do you know the relative performance of Power7 and Haswell? The implementation is not wait-free on Power7 because of HW limitation, and has significantly lower throughput than Haswell in the benchmarks.