Abstract

• 确定了对CPU utilization的不准确测量是如何影响OS的几个关键方面的
• 这篇文章提出来了一个比CPU utilization更准确的性能评估指标

In this paper, we identify how an inaccurate measurement of the CPU utilization affects several key aspects of the system such as OS statistics or the charging mechanism in data centers.

We propose a new hardware CPU accounting mechanism to improve the accuracy when measuring the CPU utilization in CMPs and compare it with the previous accounting mechanisms.

Question

作者在后文中举例：在锁定一个固定的，排除了 “OS noise” 的核上运行SPEC CPU 2,000 benchmark 171.swim， it completes its execution in 117 seconds. when swim runs together with other applications in the same core, its real execution time increases up to 4x due to task switches forced by the OS. (cache data eviction or process switch)

所以似乎是指对于一个固定的计算系统对于同一workload所花的计算时间大致相同。

Tricks

• We move all the OS activity to the first core, leaving the other cores as isolated as possible from “OS noise.”

Points

• processors with shared on-chip resources, such as CMPs 会因为其他正在运行的任务而导致不同的性能、时间和方差
• processors with shared on-chip resources, such as CMPs 由于空间上的cache共享而使得 the time spent running on the CPU 这种衡量方式不准确