Byte-addressable, non-volatile memory (NVM) is emerging as a revolutionary memory technology that provides persistency, near-DRAM performance, and scalable capacity. To facilitate its use, many NVM programming models have been proposed. However, most models require programmers to explicitly specify the data structures or objects that should reside in NVM. Such requirement increases the burden on programmers, complicates software development, and introduces opportunities for correctness and performance bugs.
We believe that requiring programmers to identify the data structures that should reside in NVM is untenable. Instead, programmers should only be required to identify durable roots - the entry points to the persistent data structures at recovery time. The NVM programming framework should then automatically ensure that all the data structures reachable from these roots are in NVM, and stores to these data structures are persistently completed in an intuitive order.
To this end, we present a new NVM programming framework, named AutoPersist, that only requires programmers to identify durable roots. AutoPersist then persists all the data structures that can be reached from the durable roots in an automated and transparent manner. We implement AutoPersist as a thread-safe extension to the Java language and perform experiments with a variety of applications running on Intel Optane DC persistent memory. We demonstrate that AutoPersist requires minimal code modifications, and significantly outperforms expert-marked Java NVM applications.
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MOD: Minimally Ordered Durable Datastructures for Persistent Memory
Persistent Memory (PM) makes possible recoverable applications that can preserve application progress across system reboots and power failures. Actual recoverability requires careful ordering of cacheline flushes, currently done in two extreme ways. On one hand, expert programmers have reasoned deeply about consistency and durability to create applications centered on a single custom-crafted durable datastructure. On the other hand, less-expert programmers have used software transaction memory (STM) to make atomic one or more updates, albeit at a significant performance cost due largely to ordered log updates.
In this work, we propose the middle ground of composable persistent datastructures called Minimally Ordered Durable datastructures (MOD). We prototype MOD as a library of C++ datastructures---currently, map, set, stack, queue and vector---that often perform better than STM and yet are relatively easy to use. They allow multiple updates to one or more datastructures to be atomic with respect to failure. Moreover, we provide a recipe to create additional recoverable datastructures.
MOD is motivated by our analysis of real Intel Optane PM hardware showing that allowing unordered, overlapping flushes significantly improves performance. MOD reduces ordering by adapting existing techniques for out-of-place updates (like shadow paging) with space-reducing structural sharing (from functional programming). MOD exposes a Basic interface for single updates and a Composition interface for atomically performing multiple updates. Relative to widely used Intel PMDK v1.5 STM, MOD improves map, set, stack, queue microbenchmark performance by 40%, and speeds up application benchmark performance by 38%.
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- Award ID(s):
- 1815656
- PAR ID:
- 10145464
- Date Published:
- Journal Name:
- ASPLOS '20: Proceedings of the Twenty-Fifth International Conference on Architectural Support for Programming Languages and Operating Systems
- Page Range / eLocation ID:
- 775 to 788
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3373376.3378472
