Amalgamated Lock-Elision

Yehuda Afek, Alexander Matveev, Oscar R. Moll, Nir Shavit

Abstract: Hardware lock-elision (HLE) introduces concurrency into legacy lock-based code by optimistically executing critical sections in a fast-path as hardware transactions. Its main limitation is that in case of repeated aborts, it reverts to a fallback-path that acquires a serial lock. This fallback-path lacks hardware-software concurrency, because all fast-path hardware transactions abort and wait for the completion of the fallback. Software lock elision has no such limitation, but the overheads incurred are simply too high.