Proactively Breaking Large Pages to Improve Memory Overcommitment Performance in VMware ESXi

Guo, Fei; Kim, Seongbeom; Baskakov, Yury; Banerjee, Ishan

doi:10.1145/2731186.2731187

Cited by 44 publications

(6 citation statements)

References 12 publications

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“…Other researchers also investigated and redesigned libraries and OS kernel internals to use the huge page feature [4], [5], [10], [11]. LPageBreak [29] opportunistically breaks huge pages to mitigate the cost of the page compaction. SmartMD [8] breaks huge pages for memory deduplication.…”

Section: Related Workmentioning

confidence: 99%

Comparison of Value- and Reference-Based Memory Page Compaction in Virtualized Systems

Aoyama

Yamada

2022

IEICE Trans. Inf. & Syst.

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The issue of copying values or references has historically been studied for managing memory objects, especially in distributed systems. In this paper, we explore a new topic on copying values v.s. references, for memory page compaction on virtualized systems. Memory page compaction moves target physical pages to a contiguous memory region at the operating system kernel level to create huge pages. Memory virtualization provides an opportunity to perform memory page compaction by copying the references of the physical pages. That is, instead of copying pages' values, we can move guest physical pages by changing the mappings of guest-physical to machine-physical pages. The goal of this paper is a quantitative comparison between value-and reference-based memory page compaction. To do so, we developed a software mechanism that achieves memory page compaction by appropriately updating the references of guest-physical pages. We prototyped the mechanism on Linux 4.19.29 and the experimental results show that the prototype's page compaction is up to 78% faster and achieves up to 17% higher performance on the memory-intensive real-world applications as compared to the default value-copy compaction scheme.

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Section: Related Workmentioning

confidence: 99%

Comparison of Value- and Reference-Based Memory Page Compaction in Virtualized Systems

Aoyama

Yamada

2022

IEICE Trans. Inf. & Syst.

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“…Ingens [63] improves THP support in terms of fairness, bloat and latency by tracking huge page utilization and access frequency of pages. Guo et al [38] proposed proactively breaking huge pages to improve memory efficiency via page sharing in virtualized environments. In summary, prior OS research has mainly focused on implementing huge page support, optimizing performance or improving memory efficiency in the presence of huge pages, with different policies applied at the virtual memory layer while fragmentation has received less attention.…”

Section: Related Workmentioning

confidence: 99%

Making Huge Pages Actually Useful

Panwar

Prasad

Gopinath

2018

Proceedings of the Twenty-Third International Conference on Architectural Support for Programming Languages and Operating Syste

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The virtual-to-physical address translation overhead, a major performance bottleneck for modern workloads, can be effectively alleviated with huge pages. However, since huge pages must be mapped contiguously, OSs have not been able to use them well because of the memory fragmentation problem despite hardware support for huge pages being available for nearly two decades.This paper presents a comprehensive study of the interaction of fragmentation with huge pages in the Linux kernel. We observe that when huge pages are used, problems such as high CPU utilization and latency spikes occur because of unnecessary work (e.g., useless page migration) performed by memory management related subsystems due to the poor handling of unmovable (i.e., kernel) pages. This behavior is even more harmful in virtualized systems where unnecessary work may be performed in both guest and host OSs.We present Illuminator, an efficient memory manager that provides various subsystems, such as the page allocator, the ability to track all unmovable pages. It allows subsystems to make informed decisions and eliminate unnecessary work which in turn leads to cost-effective huge page allocations. Illuminator reduces the cost of compaction (up to 99%), improves application performance (up to 2.3×) and reduces the maximum latency of MySQL database server (by 30×).

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“…Unfortunately, there are no such workarounds to mitigate the translation coherence overheads of hypervisor-initiated nested page table remappings. For these reasons, cross-VM memory deduplication [22,48] and page migration between NUMA memories on multi-socket systems [49][50][51] are known to be expensive. In the past, such overheads may have been mitigated by using these optimizations sparingly.…”

Section: Page Remapping In Virtualized Systemsmentioning

confidence: 99%

Hardware Translation Coherence for Virtualized Systems

Yan

Vesely

Cox

et al. 2017

Proceedings of the 44th Annual International Symposium on Computer Architecture

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To improve system performance, modern operating systems (OSes) often undertake activities that require modification of virtual-to-physical page translation mappings. For example, the OS may migrate data between physical frames to defragment memory and enable superpages. The OS may migrate pages of data between heterogeneous memory devices. We refer to all such activities as page remappings. Unfortunately, page remappings are expensive. We show that translation coherence is a major culprit and that systems employing virtualization are especially badly affected by their overheads. In response, we propose hardware translation invalidation and coherence or HATRIC, a readily implementable hardware mechanism to piggyback translation coherence atop existing cache coherence protocols. We perform detailed studies using KVM-based virtualization, showing that HATRIC achieves up to 30% performance and 10% energy benefits, for per-CPU area overheads of 2%. We also quantify HATRIC's benefits on systems running Xen and find up to 33% performance improvements.

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Proactively Breaking Large Pages to Improve Memory Overcommitment Performance in VMware ESXi

Cited by 44 publications

References 12 publications

Comparison of Value- and Reference-Based Memory Page Compaction in Virtualized Systems

Comparison of Value- and Reference-Based Memory Page Compaction in Virtualized Systems

Making Huge Pages Actually Useful

Hardware Translation Coherence for Virtualized Systems

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