This paper presents lottery scheduling, a novel randomized resource allocation mechanism. Lottery scheduling provides efficient, responsive control over the relative execution rates of computations. Such control is beyond the capabilities of conventional schedulers, and is desirable in systems that service requests of varying importance, such as databases, media-based applications, and networks. Lottery scheduling also supports modular resource management by enabling concurrent modules to insulate their resource allocation policies from one another. A currency abstraction is introduced to flexibly name, share, and protect resource rights. We also show that lottery scheduling can be generalized to manage many diverse resources, such as I/O bandwidth, memory, and access to locks. We have implemented a prototype lottery scheduler for the Mach 3.0 microkernel, and found that it provides flexible and responsive control over the relative execution rates of a wide range of applications. The overhead imposed by our unoptimized prototype is comparable to that of the standard Mach timesharing policy.

: In 1993, sizes of on-chip caches on current commercial microprocessors range from 16K bytes to 36 Kbytes. These microprocessors can be directly used in the design of a low cost single-bus shared memory multiprocessors without using any second-level cache. In this paper, we explore the viability of such a multi-microprocessor. Simulations results clearly establish that performance of such a system will be quite poor if on-chip caches are direct-mapped. On the other hand, when the on-chip caches are partially associative, the achieved level of performance is quite promising. In particular, two recently proposed innovative cache structures, the skewed associative cache organization and the semi-unified cache organization are shown to work fine. Key-words: microprocessors, shared memorymulti-microprocessors, cache, skewed-associative cache, semi-unified cache. (R'esum'e : tsvp) e-mail : drach, gefflaut, pjoubert, seznec@irisa.fr Unit e de recherche INRIA Rennes IRISA, Campus univer...