Serverless computing is an increasingly attractive paradigm in the cloud due to its ease of use and fine-grained pay-for-what-you-use billing. However, serverless computing poses new challenges to system design due to its short-lived function execution model. Our detailed analysis reveals that memory management is responsible for a major amount of function execution cycles. This is because functions pay the full critical-path costs of memory management in both userspace and the operating system without the opportunity to amortize these costs over their short lifetimes.
To address this problem, we propose Memento, a new hardware-centric memory management design based upon our insights that memory allocations in serverless functions are typically small, and either quickly freed after allocation or freed when the function exits. Memento alleviates the overheads of serverless memory management by introducing two key mechanisms: (i) a hardware object allocator that performs in-cache memory allocation and free operations based on arenas, and (ii) a hardware page allocator that manages a small pool of physical pages used to replenish arenas of the object allocator. Together these mechanisms alleviate memory management overheads and bypass costly userspace and kernel operations. Memento naturally integrates with existing software stacks through a set of ISA extensions that enable seamless integration with multiple languages runtimes. Finally, Memento leverages the newly exposed memory allocation semantics in hardware to introduce a main memory bypass mechanism and avoid unnecessary DRAM accesses for newly allocated objects.
We evaluate Memento with full-system simulations across a diverse set of containerized serverless workloads and language runtimes. The results show that Memento achieves function execution speedups ranging between 8–28% and 16% on average. Furthermore, Memento hardware allocators and main memory bypass mechanisms drastically reduce main memory traffic by 30% on average. The combined effects of Memento reduce the pricing cost of function execution by 29%. Finally, we demonstrate the applicability of Memento beyond functions, to major serverless platform operations and long-running data processing applications.
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MemPerf: Profiling Allocator-Induced Performance Slowdowns
The memory allocator plays a key role in the performance of applications, but none of the existing profilers can pinpoint performance slowdowns caused by a memory allocator. Consequently, programmers may spend time improving application code incorrectly or unnecessarily, achieving low or no performance improvement. This paper designs the first profiler—MemPerf—to identify allocator-induced performance slowdowns without comparing against another allocator. Based on the key observation that an allocator may impact the whole life-cycle of heap objects, including the accesses (or uses) of these objects, MemPerf proposes a life-cycle based detection to identify slowdowns caused by slow memory management operations and slow accesses separately. For the prior one, MemPerf proposes a thread-aware and type-aware performance modeling to identify slow management operations. For slow memory accesses, MemPerf utilizes a top-down approach to identify all possible reasons for slow memory accesses introduced by the allocator, mainly due to cache and TLB misses, and further proposes a unified method to identify them correctly and efficiently. Based on our extensive evaluation, MemPerf reports 98% medium and large allocator-reduced slowdowns (larger than 5%) correctly without reporting any false positives. MemPerf also pinpoints multiple known and unknown design issues in widely-used allocators.
more » « less- Award ID(s):
- 2312396
- PAR ID:
- 10541495
- Publisher / Repository:
- OOPSLA
- Date Published:
- Journal Name:
- Proceedings of the ACM on Programming Languages
- Volume:
- 7
- Issue:
- OOPSLA2
- ISSN:
- 2475-1421
- Page Range / eLocation ID:
- 1418 to 1441
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1145/3622848
