Managing more physical with less virtual
Rohit Chawla, Steve Baumel · Software Practice and Experience · 2000
Recent explosive growth in physical memory configurations inverts the problem faced by traditional operating systems, which were built around the assumption of limited physical memory and plentiful virtual memory. With the introduction of the Pentium Pro, there is an aberration in the historical trend towards increased virtual space. Such processors have 36-bit physical and 32-bit logical addressing; with traditional algorithms, the smaller virtual space limits the number of concurrent processes as well as the total physical memory usable by an application. To address these problems, two general principles can be applied to any operating system to reduce its virtual memory needs: first, multiplexing different physical addresses over the same virtual—as opposed to multiplexing different virtual over the same physical, where the optimization was to share the physical memory across multiple processes; second, optimize virtual consumption by kernel pagepool data, by organizing data structures to extend their physical memory reach using the same amount of virtual space. Copyright © 2000 John Wiley & Sons, Ltd.