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We have designed, implemented and evaluated
an automatic application-controlled file
prefetching system called AASFP that is particularly useful for multimedia applications
with irregular disk access patterns.
It is automatic in the sense that the system exploits application-specific
disk access patterns for file prefetching without any manual programming.
The idea of extracting I/O related code from the original code is very general
and we believe it is applicable to other languages such as C++ or Java as well;
the required effort to support other languages should also be comparable to this work.
The Linux-based AASFP prototype implementation is
fully operational and provides up to 54% overall application improvement for
a real-world volume visualization
application. Currently we are continuing the development of AASFP. We are
extending the current prototype to allow
multiple I/O-intensive applications to run on an AASFP-based system
simultaneously. The key design issue here is to allocate disk resource
among multiple processes, depending on their urgency on disk
access requirements. We are also building on the AASFP technology
to develop a high-performance I/O subsystem for large-scale
parallel computing clusters.
Finally we are extending the AASFP prototype
to the context of Network File System (NFS), and generalize the
application-specific prefetching to a more general concept called
active file server architecture.
Here, in addition to standard file access service,
we allow an application to deposit an arbitrary program either to manipulate
accessed file data on the fly such as compression or encryption (data plane), or to exercise
different control policies such as prefetching, replacement, and garbage collection (control plane).
The active file server architecture significantly enhances the customizability and
flexibility of file access, and thus improves both the performance of individual
applications and the overall efficiency of the file system.
A major research challenge for active file server is the design of
a procedural interface for application program segments that is both
general and efficient enough to accommodate various control plane or data plane
processing requirements, and sufficiently rigid to ensure data security and safety.
We plan to use AASFP with NFS as a case study to gain some concrete experiences with
the architectural design issues associated with active file server.
The code of this project will be available for download at the URL: https://www.ecsl.cs.sunysb.edu/archive.html.
Next: Acknowledgments
Up: A Decoupled Architecture for
Previous: Performance Results and Analysis
chuan-kai yang
2002-04-15