We propose ecoTLB —software-based eventual translation lookaside buffer (TLB) coherence—which eliminates the overhead of the synchronous TLB shootdown mechanism in operating systems that use address space identifiers (ASIDs). With an eventual TLB coherence, ecoTLB improves the performance of free and page swap operations by removing the inter-processor interrupt (IPI) overheads incurred to invalidate TLB entries. We show that the TLB shootdown has implications for page swapping in particular in emerging, disaggregated data centers and demonstrate that ecoTLB can improve both the performance and the specific swapping policy decisions using ecoTLB ’s asynchronous mechanism. We demonstrate that ecoTLB improves the performance of real-world applications, such as Memcached and Make, that perform page swapping using Infiniswap , a solution for next generation data centers that use disaggregated memory, by up to 17.2%. Moreover, ecoTLB improves the 99th percentile tail latency of Memcached by up to 70.8% due to its asynchronous scheme and improved policy decisions. Furthermore, we show that recent features to improve security in the Linux kernel, like kernel page table isolation (KPTI), can result in significant performance overheads on architectures without support for specific instructions to clear single entries in tagged TLBs, falling back to full TLB flushes. In this scenario, ecoTLB is able to recover the performance lost for supporting KPTI due to its asynchronous shootdown scheme and its support for tagged TLBs. Finally, we demonstrate that ecoTLB improves the performance of free operations by up to 59.1% on a 120-core machine and improves the performance of Apache on a 16-core machine by up to 13.7% compared to baseline Linux, and by up to 48.2% compared to ABIS, a recent state-of-the-art research prototype that reduces the number of IPIs.

中文翻译：

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ECO TLB

我们建议生态TLB— 基于软件的最终转换后备缓冲区 (TLB) 一致性 — 它消除了使用地址空间标识符 (ASID) 的操作系统中同步 TLB 击落机制的开销。随着最终的 TLB 连贯性，生态TLB提高性能自由和页面交换通过消除使 TLB 条目无效所产生的处理器间中断 (IPI) 开销来进行操作。我们展示了 TLB 击落对页面交换有影响，特别是在新兴的、分散的数据中心中，并证明了生态TLB可以提高性能和特定的交换策略决策使用生态TLB的异步机制。我们证明生态TLB提高了实际应用程序的性能，例如 Memcached 和 Make，这些应用程序使用执行页面交换无限交换，使用分解内存的下一代数据中心的解决方案，最多可提高 17.2%。而且，生态TLB由于其异步方案和改进的策略决策，Memcached 的第 99 个百分位尾部延迟提高了 70.8%。此外，我们展示了提高 Linux 内核安全性的最新功能，如内核页表隔离 (KPTI)，可能会导致架构上显着的性能开销，而不支持特定指令来清除标记 TLB 中的单个条目，从而回退到完整的 TLB冲洗。在这种情况下，生态TLB由于其异步击落方案和对标记 TLB 的支持，能够恢复支持 KPTI 所损失的性能。最后，我们证明生态TLB在 120 核机器上的自由操作性能提升高达 59.1%，与基线 Linux 相比，Apache 在 16 核机器上的性能提升高达 13.7%，与 ABIS 相比提升高达 48.2%，最近最先进的研究原型减少了 IPI 的数量。