A Lock-Free O(1) Event Pool and Its Application to Share-Everything PDES Platforms

Abstract

The large diffusion of highly-parallel sharedmemory multi-core machines has led Parallel Discrete Event Simulation (PDES) platforms to a shift towards a shareeverything model. This model is based on loose coupling between simulation objects and threads, lasting (as an extreme) no more than the lifetime of individual events. Concurrent threads can therefore CPU-dispatch events destined to any object at any point in time, thus fully sharing the workload of events to be processed on a fine grain basis. This demands for efficient mechanisms to share the overall pool of pending events by enabling parallelism in insertion and extraction operations. In this article we present a lock-free event pool which also provides amortized O(1) time complexity for both insertions and extractions. It can sustain highly concurrent accesses, while not leading to noticeable performance degradation when scaling up the thread count. Experimental results demonstrate that our solution stands as a core facility capable of further raising up the pragmatical impact of such an emerging shareeverything PDES paradigm.

A Non-blocking Buddy System for Scalable Memory Allocation on Multi-core Machines

“…In these contexts, the de-schedule of a lock-holding thread because of CPU-steals can lead to detrimental performance and waste of energy because of the stretch of the spin-locking phase by other threads attempting to access the same critical section. Along this direction, a lot of effort has been spent in developing non-blocking versions of classical data structures such as lists or queues [5], [6], hash-tables [7], registers [8], [9] binary-search trees [10], [11] and priority queues [12], [13]. 1 https://github.com/HPDCS/NBBS In any case, while many solutions have been devised in order to reduce the negative impact of concurrency and synchronization in memory allocation/deallocation by relying on pre-reserving or caching, no one fully faces the problem of concurrent accesses to back-end allocators.…”

A Conflict-Resilient Lock-Free Calendar Queue for Scalable Share-Everything PDES Platforms

“…spinlocks) does not ensure scalability, thus figuring out as an adequate approach limited to a reduced number of threads. For this reason, recent studies [10,5,14] have targeted the design of event pool data structures based on the lock-free paradigm. Here concurrent threads attempt to perform their operations-either an extraction or an insertion-without the need to take any lock.…”

“…In this article, we take the lock-free calendar queue presented in [14] as our reference and present the design of an innovative version that has the property of being conflictresilient 1 . Conflict resilience is achieved in relation to concurrent extractions.…”

“…A current trend is the one of building PDES platforms as "share-everything" systems [14]. In this paradigm, an event (which may target any simulation object) can be picked by any worker thread for actual processing.…”

“…Indeed, each worker thread picks events with lower timestamps without considering any partial view of the pending event set-the view generated by partitioning simulation objects across threads. PDES platforms adhering to the share-everything paradigm, or at least tending to this type of architectural organization, can be found in [4,19,10,5,14].…”