grigory-rechistov / stamp-rtm Goto Github PK

When performing lock elision, according to Intel manual, or the presentation here: http://www.halobates.de/adding-lock-elision-to-linux.pdf one should check whether the lock is free after XBEGIN instruction, and before everything else. This way, the transaction will be notified when another thread acquires the lock, and should abort to avoid committing while the other thread is executing in an unprotected critical section.

This, however, is not implemented in lib/rtm.h and lib/tm.h, where the lock is only used on the fallback path, but not on transactional path. With pthread_mutex_t I would say it is difficult, because there is no mechanism for us to check whether the mutex is held without acquiring it.