Despite great advancements in hardware-assisted virtualization of the x86 architecture, certain workloads still suffer significant overhead. This article dissects said overhead in the context of multi-threading. We describe the state-of-the-art, pinpoint challenges, and suggest improvements, aiming to provide a valuable reference to developers and users of virtualization systems alike. We study the virtualization overhead of the PARSEC and SPLASH2X multithreaded benchmarks in a variety of scenarios using a state-of-the-art system. Through controlled experiments, source code analysis and literature review, we quantify the virtualization overhead multithreading still induces and link it to its root causes, after which we suggest possible mitigation strategies. Multithreading still induces high virtualization overhead, mainly caused by synchronization, spinning at user level and NUMA management. The overhead is diverse in nature and embodiment as it is a function of many system and workload properties. System-level solutions are feasible, but often imply difficult trade-offs. Systematic workload optimization is a promising alternative.

中文翻译：

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X86最新技术和尚存挑战中的多线程虚拟化开销

尽管x86架构的硬件辅助虚拟化取得了很大进步，但某些工作负载仍然遭受大量开销。本文在多线程上下文中剖析了上述开销。我们描述了最新的，精确的挑战，并提出了改进建议，旨在为虚拟化系统的开发人员和用户提供有价值的参考。我们使用最先进的系统在各种情况下研究PARSEC和SPLASH2X多线程基准测试的虚拟化开销。通过受控实验，源代码分析和文献回顾，我们量化了虚拟化开销，但多线程仍会引起该问题并将其链接到其根本原因，然后我们提出了可能的缓解策略。多线程仍然会带来很高的虚拟化开销，主要是由同步，在用户级别旋转和NUMA管理引起的。由于开销是许多系统和工作负载属性的函数，因此开销在本质和实施方式上是多种多样的。系统级解决方案是可行的，但通常意味着难以取舍。系统的工作负载优化是一种有前途的选择。