5,967 research outputs found
k2U: A General Framework from k-Point Effective Schedulability Analysis to Utilization-Based Tests
To deal with a large variety of workloads in different application domains in
real-time embedded systems, a number of expressive task models have been
developed. For each individual task model, researchers tend to develop
different types of techniques for deriving schedulability tests with different
computation complexity and performance. In this paper, we present a general
schedulability analysis framework, namely the k2U framework, that can be
potentially applied to analyze a large set of real-time task models under any
fixed-priority scheduling algorithm, on both uniprocessor and multiprocessor
scheduling. The key to k2U is a k-point effective schedulability test, which
can be viewed as a "blackbox" interface. For any task model, if a corresponding
k-point effective schedulability test can be constructed, then a sufficient
utilization-based test can be automatically derived. We show the generality of
k2U by applying it to different task models, which results in new and improved
tests compared to the state-of-the-art.
Analogously, a similar concept by testing only k points with a different
formulation has been studied by us in another framework, called k2Q, which
provides quadratic bounds or utilization bounds based on a different
formulation of schedulability test. With the quadratic and hyperbolic forms,
k2Q and k2U frameworks can be used to provide many quantitive features to be
measured, like the total utilization bounds, speed-up factors, etc., not only
for uniprocessor scheduling but also for multiprocessor scheduling. These
frameworks can be viewed as a "blackbox" interface for schedulability tests and
response-time analysis
Quasinormal Modes and Hidden Conformal Symmetry of Warped dS Black Hole
In this paper, we analytically calculate the quasinormal modes of scalar,
vector, tensor, and spinor perturbations of the warped dS black hole. There
are two horizons for the warped dS black hole, namely, the black hole
horizon and the cosmological horizon . In the calculation, we impose
the ingoing boundary condition at the black hole horizon and the outgoing
boundary condition at the cosmological horizon. We also investigate the hidden
conformal symmetry of the warped dS black hole in the region between the
black hole horizon and the cosmological horizon . We use the hidden
conformal symmetry to construct the quasinormal modes in an algebraic way and
find that the results agree with the analytically ones. It turns out that the
frequencies of the quasinormal modes could be identified with the poles in the
thermal boundary-boundary correlators.Comment: 26 pages, references added, published versio
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