Avoiding TLB Shootdowns Through Self-Invalidating TLB Entries
Avoiding TLB Shootdowns Through Self-Invalidating TLB Entries
复制标题
通过自我失效 TLB 条目避免 TLB 被击落
DOI：
10.1109/pact.2017.38
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
G. Loh
中科院分区：
文献类型：
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作者：
Amro Awad;Arkaprava Basu;S. Blagodurov;Yan Solihin;G. Loh
更新过程的页面表条目（PTE）将在任何系统的TLBS陈旧中呈现该PTE的任何现有副本。为了防止进程使用陈旧的TLB条目进行非法内存访问，操作系统（OS）执行了昂贵的TLB射击操作。我们没有明确发行枪击，而是提出了一个协调的TLB和PAGE表管理机制，其中每个TLB条目都有过期时间。过期的TLB条目被视为无效。对于每个PTE，操作系统随后跟踪任何TLB输入的最新到期时间可能会缓存该PTE。如果OS在相应的最新到期时间已经通过时，则不会发出枪击。作为需要快速TLB射击的新兴用例，我们考虑由不同类型的内存组成的内存系统（例如，更快的DRAM和较慢的非挥发性内存），在这些内存中，希望将积极的迁移保持在更快的内存中，但是每个页面都无法迁移，因为每个迁移都需要迁移，因为每个迁移都需要PTE更新和相应的TLB射击。我们证明，通过站点增强的这种异质记忆系统可以通过避免超过65％的射击下的65％的射击，可以在类似的系统中平均提高45.5％的性能45.5％。
Updates to a process's page table entry (PTE) renders any existing copies of that PTE in any of a system's TLBs stale. To prevent a process from making illegal memory accesses using stale TLB entries, the operating system (OS) performs a costly TLB shootdown operation. Rather than explicitly issuing shootdowns, we propose a coordinated TLB and page table management mechanism where an expirationtime is associated with each TLB entry. An expired TLB entry is treated as invalid. For each PTE, the OS then tracks the latest expiration time of any TLB entry potentially caching that PTE. No shootdown is issued if the OS modifies a PTE when its corresponding latest expiration time has already passed.In this paper, we explain the hardware and OS support required to support Self-invalidating TLB entries (SITE). As an emerging use case that needs fast TLB shootdowns, we consider memory systems consisting of different types of memory (e.g., faster DRAM and slower non-volatile memory) where aggressive migrations are desirable to keep frequently accessed pages in faster memory, but pages cannot migratetoo often because each migration requires a PTE update and corresponding TLB shootdown. We demonstrate that such heterogeneous memory systems augmented with SITE can allow an average performance improvement of 45.5% over a similar system with traditional TLB shootdowns by avoiding more than 65% of the shootdowns.