延迟存储:一种降低虚拟机退出开销的方法

Delay storing:a method to reduce the cost of virtual machine exit

研究了虚拟机退出及恢复运行时的开销问题,提出了一种用于降低虚拟机切换时进行保存及恢复现场的开销的延迟存储方法。该方法的主要思想是利用修改虚拟机软件源代码的方式,通过判断虚拟机恢复运行时是否依然是上次退出时的同一个虚拟机,来减少需要保存和恢复的寄存器数量。这个方法不需要对硬件设计进行改动,可以支持多核操作系统和多个虚拟机同时运行的情况,因此具有广泛的适用性。在龙芯3A1500处理器平台上的试验结果显示,上述延迟存储方法与现有方法相比,可以降低虚拟机退出开销65%,虚拟机整体性能提升3%到10%。

The cost of virtual machines＇ exit and restoration was studies, and a method based on delay storing was proposed to reduce the cost of saving and restoring registers when virtual machines exit or resume. The main mechanism of the method is to reduce the amount of registers to be saved and restored by changing the source code of the virtual machine software and judging whether the virtual machine in resuming is still the same one that exited last time. The proposed method needs no hardware change, and supports muhicore operating systems and concurrent operation of multiple virtual machines, leading to a wide applicability. The results of the test conducted on the Loongson 3A1500 platform demonstrated that the cost of virtual machine exit of the proposed method was reduced by 65% compared with the existing method, and the performance of the whole virtual machine was increase by 3% to 10%.