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The proliferation of fast, dense, byte-addressable nonvolatile memory suggests the possibility of keeping data in pointer-rich “in-memory” format across program runs and even crashes. For full generality, such data requires dynamic memory allocation. Toward this end, we introduce _recoverability_, a correctness criterion for persistent allocators, together with a nonblocking allocator, _Ralloc_, that satisfies this criterion. Ralloc is based on _LRMalloc_, with three key innovations. First, we persist just enough information during normal operation to permit reconstruction of the heap after a full-system crash. Our reconstruction mechanism performs garbage collection (GC) to identify and remedy any failure-induced memory leaks. Second, in support of GC, we introduce the notion of _filter functions_, which identify the locations of pointers within persistent blocks. Third, to allow persistent regions to be mapped at an arbitrary address, we employ the position-independent pointer representation of Chen et al., both in data and in allocator metadata. Experiments show that Ralloc provides scalable performance competitive to that of both _Makalu_, the state-of-the-art lock-based persistent allocator, and the best transient allocators (e.g.,_JEMalloc_).
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Understanding and optimizing persistent memory allocation
The proliferation of fast, dense, byte-addressable nonvolatile memory suggests that data might be kept in pointer-rich “in-memory” format across program runs and even process and system crashes. For full generality, such data requires dynamic memory allocation, and while the allocator could in principle be “rolled into” each data structure, it is desirableto make it a separate abstraction. Toward this end, we introduce _recoverability_, a correctness criterion for persistent allocators, together with a nonblocking allocator, _Ralloc,_ that satisfies this criterion. Ralloc is based on the _LRMalloc_ of Leite and Rocha, with four key innovations: First, we persist just enough information during normal operation to permit a garbage collection (GC) pass to correctly reconstruct the heap in the wake of a full-system crash. Second, we introduce the notion of _filter functions_, which identify the locations of pointers within persistent blocks to mitigate the limitations of conservative GC. Third, we reorganize the layout of the heap to facilitate the incremental allocation of physical space. Fourth, we employ position-independent (offset-based) pointers to allow persistent regions to be mapped at an arbitrary address. Experiments show Ralloc to be performance-competitive with both _Makalu_, the state-of-the-art lock-based persistent allocator, and such transient allocators as LRMalloc and JEMalloc. In particular, reliance on GC and offline metadata reconstruction allows Ralloc to pay almost nothing for persistence during normal operation.
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- PAR ID:
- 10187404
- Date Published:
- Journal Name:
- International Symposium on Memory Management
- Page Range / eLocation ID:
- 60 to 73
- 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/10.1145/3381898.3397212
