Do-It-Yourself Virtual Memory Translation

Alam, Hanna; Zhang, Tianhao; Erez, Mattan; Etsion, Yoav

doi:10.1145/3079856.3080209

Cited by 40 publications

(23 citation statements)

References 28 publications

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“…Use of large pages to increase TLB-coverage [34,35,36,55,57,63,64,66] and additional MMU structures to cache multiple levels of the page-tables [19,24,26] are some of the techniques widely adopted in commercial systems. In addition, researchers have also proposed TLB-speculation [20,60], prefetching translations [47,53,62], eliminating or devirtualizing virtual memory [42], or exposing virtual memory system to applications to make the case for application-specific address translation [16].…”

Section: Virtual Memorymentioning

confidence: 99%

“…An important feature of Mitosis is that it requires no changes to applications or hardware, and is easy to use on a perapplication basis. For this reason, Mitosis is readily deployable and complementary to emerging hardware techniques to reduce address translation overheads like segmentation [21,49], PTE coalescing [58,59] and user-managed virtual memory [16]. We will release our implementation of Mitosis to enable future research on page-table placement and plan to upstream our changes to Linux.…”

Section: Introductionmentioning

confidence: 99%

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Mitosis: Transparently Self-Replicating Page-Tables for Large-Memory Machines

Achermann

Panwar²,

Bhattacharjee

et al. 2020

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

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Multi-socket machines with 1-100 TBs of physical memory are becoming prevalent. Applications running on multi-socket machines suffer non-uniform bandwidth and latency when accessing physical memory. Decades of research have focused on data allocation and placement policies in NUMA settings, but there have been no studies on the question of how to place page-tables amongst sockets. We make the case for explicit page-table allocation policies and show that pagetable placement is becoming crucial to overall performance.We propose Mitosis to mitigate NUMA effects on page-table walks by transparently replicating and migrating page-tables across sockets without application changes. This reduces the frequency of accesses to remote NUMA nodes when performing page-table walks. Mitosis uses two components: (i) a mechanism to enable efficient page-table replication and migration; and (ii) policies for processes to efficiently manage and control page-table replication and migration.We implement Mitosis in Linux and evaluate its benefits on real hardware. Mitosis improves performance for large-scale multi-socket workloads by up to 1.34x by replicating pagetables across sockets. Moreover, it improves performance by up to 3.24x in cases when the OS migrates a process across sockets by enabling cross-socket page-table migration.

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Section: Virtual Memorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mitosis: Transparently Self-Replicating Page-Tables for Large-Memory Machines

Achermann

Panwar²,

Bhattacharjee

et al. 2020

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

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show abstract

“…Huge pages have become vital for mitigating address translation overheads of modern workloads as non-linear scaling of the hardware cost, energy consumption and lookup latency has impacted the growth of TLB capacity [40,49,63]. Though each address translation may require up to 6× more memory lookups in virtualized systems due to the two-dimensional page tables [31], modern hardware can nearly match the address translation efficiency of virtualized environments with the native systems by utilizing huge pages [61].…”

Section: Motivationmentioning

confidence: 99%

“…Address translation overhead has become a major performance bottleneck for modern data processing applications as TLB scaling has not caught up with the growth of memory capacity in recent times [31,40,49,63]. This has inspired support for huge pages in most processors [4,5,53].…”

Section: Introductionmentioning

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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“…With the continuously increasing application footprints and a corresponding growth of memory capacity, virtual-tophysical memory address translation tends to be a new bottleneck of system performance [8]. Modern computer systems typically employ translation lookaside buffer (TLB) as a cache to store the recent virtual-to-physical address translations for faster retrieval in the future.…”

Section: Introductionmentioning

confidence: 99%

Supporting Superpages and Lightweight Page Migration in Hybrid Memory Systems

Wang

Liu

Liao

et al. 2019

ACM Trans. Archit. Code Optim.

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Superpages have long been used to mitigate address translation overhead in big memory systems. However, superpages often preclude lightweight page migration, which is crucial for performance and energy efficiency in hybrid memory systems composed of DRAM and non-volatile memory (NVM). In this paper, we propose a novel memory management mechanism called Rainbow to bridge this fundamental conflict between superpages and lightweight page migration. Rainbow manages NVM at the superpage granularity, and uses DRAM to cache frequently-accessed (hot) small pages in each superpage. Correspondingly, Rainbow utilizes split TLBs to support different page sizes. By introducing an efficient hot page identification mechanism and a novel NVM-to-DRAM address remapping mechanism, Rainbow supports lightweight page migration while without splintering superpages. Experimental results show that Rainbow can significantly reduce applications' TLB misses by 99.8%, and improve application performance (IPC) by up to 2.9X (43.0% on average) when compared to a state-of-the-art memory migration policy without superpage support.

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Do-It-Yourself Virtual Memory Translation

Cited by 40 publications

References 28 publications

Mitosis: Transparently Self-Replicating Page-Tables for Large-Memory Machines

Mitosis: Transparently Self-Replicating Page-Tables for Large-Memory Machines

Making Huge Pages Actually Useful

Supporting Superpages and Lightweight Page Migration in Hybrid Memory Systems

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