The aperiodic multiprocessor utilization bound for liquid tasks

Real-time scheduling theory has developed powerful tools for translating conditions on aggregate system utilization into per-task schedulability guarantees. The main breakthrough has been Liu and Layland's utilization bound for schedulability of periodic tasks. In 2001 this bound was generalized by Abdelzaher and Lu to the aperiodic task case. In this paper we further generalize the aperiodic bound to the case of multiprocessors, and present key new insights into schedulability, analysis of aperiodic tasks. We consider a special task model, called the liquid task model, representative of high-performance servers with aperiodic workloads, such as network routers, web servers, proxies, and real-time databases. For this model, we derive the optimal multiprocessor utilization bound, defined on a utilization-like metric we call "synthetic utilization". This bound allows developing constant-time admission control tests that provide utilization-based absolute delay, tees. We show that the real utilization of admitted tasks can be close to unity even when synthetic utilization is kept below the bound. Thus, our results lead to multiprocessor systems which combine constant-time admission control with high utilization while making no periodicity assumptions regarding the task arrival pattern.

NATURVETENSKAP Data- och informationsvetenskap Datorteknik hsv//swe
NATURAL SCIENCES Computer and Information Sciences Computer Engineering hsv//eng
real-time databases
multiprocessors
proxies
web servers
aperiodic multiprocessor utilization bound
constant-time admission control
task model
liquid tasks
network routers
high-performance servers
aggregate system utilization
per-task schedulability
real-time scheduling theory

Andersson, Björn,1974Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)bjornand (författare)
Jonsson, Jan,1962Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)janjo (författare)
Sharma, V. (författare)
Nguyen, M. (författare)
Chalmers tekniska högskola (creator_code:org_t)

Ingår i:8th IEEE Real-Time and Embedded Technology and Applications Symposium, 2002. Proceedings, s. 173-1841545-34210769517390

Av författaren/redakt...: Abdelzaher, T.; Andersson, Björn ...; Jonsson, Jan, 19 ...; Sharma, V.; Nguyen, M.

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