nru

NRU is an initialism that can refer to several different concepts depending on context. It is most commonly encountered as a page replacement algorithm in computer operating systems and as a designation for certain universities in Russia. Other uses exist but are less common.

Not Recently Used (NRU) is a class of page replacement strategies used in virtual memory systems. A typical NRU implementation tracks, for each loaded page, a reference bit (whether the page has been accessed since the last reset) and a modified bit (dirty, indicating writes). Periodically, the system divides pages into four classes based on these bits: (0,0), (0,1), (1,0), and (1,1). When a page needs to be evicted, the system selects a candidate from the lowest-numbered non-empty class, favoring pages that have not been recently referenced. After a class reclassification, reference bits are often reset to 0. NRU is simple to implement and inexpensive but can be less effective than algorithms that maintain more detail about page usage, such as aging or least-recently-used variants.

In Russia, National Research University (NRU) is a designation given by the government to a select group of universities recognized for research activity and academic quality. NRU designation typically comes with increased funding, autonomy, and a mandate to pursue advanced research. The National Research University Higher School of Economics (NRU HSE) is a prominent example. The NRU status is part of a broader national program to promote research universities and is used in English-language references to identify such institutions.