I had a notion I had seen STM discussed at lwn.net, and did a simple search. This comment http://lwn.net/Articles/336039/ http://lwn.net/Articles/336039/ , may

I had a notion I had seen STM discussed at lwn.net, and did a simple search. This comment http://lwn.net/Articles/336039/ http://lwn.net/Articles/336039/ , may explain it: I read all the relevant theoretical papers, and poured over the code of existing implementations. I tried to implement a simple STM mechanism, and it's not possible for any amount of data more than 16-bytes