Transactional Memory: An Idea Ahead of Its Time
Brown University (04/09/12) Richard Lewis
Brown University researchers were studying theoretical transaction memory technologies, which attempts to seamlessly and concurrently handle shared revisions to information, about 20 years ago. Now those theories have become a reality. Intel recently announced that transactional memory will be included in its mainstream Haswell hardware architecture by next year, and IBM has adopted transactional memory in the Blue Gene/Q supercomputer. The problem that transaction memory aimed to solve is that core processors were changing in fundamental ways, says Brown professor Maurice Herlihy. Herlihy developed a system of requests and permissions in which operations are begun and logged in, but wholesale changes, or transactions, are not made before the system checks to be sure no other thread has suggested changes to the pending transaction as well. If no other changes have been requested, the transaction is consummated, but if there is another change request, the transaction is aborted and the threads start anew. Intel says its transactional memory is "hardware [that] can determine dynamically whether threads need to serialize through lock-protected critical sections, and perform serialization only when required."
Brown University (04/09/12) Richard Lewis
Brown University researchers were studying theoretical transaction memory technologies, which attempts to seamlessly and concurrently handle shared revisions to information, about 20 years ago. Now those theories have become a reality. Intel recently announced that transactional memory will be included in its mainstream Haswell hardware architecture by next year, and IBM has adopted transactional memory in the Blue Gene/Q supercomputer. The problem that transaction memory aimed to solve is that core processors were changing in fundamental ways, says Brown professor Maurice Herlihy. Herlihy developed a system of requests and permissions in which operations are begun and logged in, but wholesale changes, or transactions, are not made before the system checks to be sure no other thread has suggested changes to the pending transaction as well. If no other changes have been requested, the transaction is consummated, but if there is another change request, the transaction is aborted and the threads start anew. Intel says its transactional memory is "hardware [that] can determine dynamically whether threads need to serialize through lock-protected critical sections, and perform serialization only when required."
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