As with paging , this mapping requires two memory references per logical address , effectively slowing the computer system by a factor of two , unless something is done 如同对源程序编码给予定位一样,这种变换需要每一逻辑地址有两个内存参考。如果没有什么措施,则会有效地使用计算机系统运算速度降低一半。
As we saw earlier in the section on linux and segmentation , each segment descriptor uses same set of addresses for linear addressing , minimizing the need to use the segmentation unit to convert logical addresses to linear addresses 前面介绍linux分段模型时已提到,每个分段描述符都使用相同的地址集进行线性寻址,从而尽可能降低使用分段单元将逻辑地址转换成线性地址的需要。
In a virtual - memory system , programs are given access to a larger set of addresses than is physically available , and a dedicated memory manager maps these logical addresses to actual locations , using temporary storage on disc to hold the overflow 在虚拟内存系统中,程序可以访问超出可用物理内存的更大的地址集合,专用内存管理程序将这些逻辑地址映射到实际地址,使用磁盘上的临时存储保存超出的部分。
In computing, a logical address is the address at which an item (memory cell, storage element, network host) appears to reside from the perspective of an executing application program.