Transactional memory

About: Transactional memory is a research topic. Over the lifetime, 2365 publications have been published within this topic receiving 60818 citations.

Improving STM performance with transactional structs

Abstract: Software transactional memory (STM) has made it significantly easier to write correct concurrent programs in Haskell. Its performance, however, is limited by several inefficiencies. While safe concurrent computations are easy to express in Haskell's STM, concurrent data structures suffer unfortunate bloat in the implementation due to an extra level of indirection for mutable references as well as the inability to express unboxed mutable transactional values. We address these deficiencies by introducing TStruct to the GHC run-time system, allowing strict unboxed transactional values as well as mutable references without an extra indirection. Using TStruct we implement several data structures, discuss their design, and provide benchmark results on a large multicore machine. Our benchmarks show that concurrent data structures built with TStruct out-scale and out-perform their TVar-based equivalents.

Resolving Semantic Conflicts in Word Based Software Transactional Memory

Abstract: In this paper we describe a technique for addressing semantic conflicts within word based Software Transactional Memory. A semantic conflict is considered to be some application condition which causes transactions to explicitly abort. Session locking and a companion Contention Management Policy are described which support the parallel exploration of multiple transaction schedules at run time, to resolve semantic conflicts. Performance figures are provided to demonstrate the effectiveness of our technique when semantic conflicts are introduced into established benchmarks.

Unbounded transactional memory with forward progress guarantees using a hardware global lock

Abstract: A processing device implementing unbounded transactional memory with forward progress guarantees using a hardware global lock is disclosed A processing device of the disclosure includes a hardware transactional memory (HTM) hardware contention manager to cause a bounded transaction to be translated to an unbounded transaction, the unbounded transaction to acquire a global hardware lock for the unbounded transaction, the global hardware lock read by bounded transactions that abort when the global hardware lock is taken The processing device further includes an execution unit communicably coupled to the HTM hardware contention manager to execute instructions of the unbounded transaction without speculation, the unbounded transaction to release the global hardware lock upon completion of execution of the instructions

Unifying Memory and Database Transactions

Abstract: Software Transactional Memory is a concurrency control technique gaining increasing popularity, as it provides high-level concurrency control constructs and eases the development of highly multi-threaded applications. But this easiness comes at the expense of restricting the operations that can be executed within a memory transaction, and operations such as terminal and file I/O are either not allowed or incur in serious performance penalties. Database I/O is another example of operations that usually are not allowed within a memory transaction. This paper proposes to combine memory and database transactions in a single unified model, benefiting from the ACID properties of the database transactions and from the speed of main memory data processing. The new unified model covers, without differentiating, both memory and database operations. Thus, the users are allowed to freely intertwine memory and database accesses within the same transaction, knowing that the memory and database contents will always remain consistent and that the transaction will atomically abort or commit the operations in both memory and database. This approach allows to increase the granularity of the in-memory atomic actions and hence, simplifies the reasoning about them.