Increasing File System Burstiness for Energy Efficiency
Athanasios E. Papathanasiou,
and
Michael L. Scott.
Computer Science Department
University of Rochester
Several important devices -- hard disks and wireless networks in
particular -- support low-power modes that can save significant energy
if the device is inactive for relatively long periods of time (typically
tens of seconds). Modern file systems, however, are typically designed
to maximize throughput and to minimize I/O latency, not to minimize
energy. Even under a light workload, idle times tend to be too short to
exploit for energy savings.
We propose that the file systems used in mobile platforms and in
underloaded servers be re-designed to create a bursty access pattern:
one that increases the average length of idle intervals for devices with
low power modes. Toward this end we are currently exploring aggressive
prefetching (of the sort previously used to prepare local disk caches
for disconnected operation), bursty periodic update (with increased
variance in time-to-stable-storage), and scheduling algorithms that (a)
embody knowledge of device power characteristics, and (b) coordinate I/O
activities across all running applications. To mitigate the effects of
possible disk congestion, we introduce a notion of urgency, and use it
to order requests.
Using trace-driven simulation, we have found that by re-shaping the
low-level disk access pattern we can save up to 55% of total disk energy
in such common applications as mp3 playback and encoding, data copying,
and games. (This is in comparison to a baseline IBM TravelStar disk
with the best reactive [timer-based] spin-down policy). We are
currently working on an implementation of our ideas in the Linux EXT2
file system.
Publications
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Aggressive Prefetching: An Idea Whose Time Has Come.
In
Proceedings of the Tenth Workshop on Hot Topics in Operating Systems (HotOS X),
June 12-15, 2005, Eldorado Hotel, Santa Fe, NM, USA.
Available:
PDF (720KB),
Compressed Postscript (680KB).
Slides:
PDF (232KB),
Compressed Postscript (720KB).
Handouts:
PDF (208KB),
Compressed Postscript (704KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Power-efficient Server-class Performance from Arrays of Laptop Disks
Technical Report 837, Computer Science Department, University of Rochester, May 2004.
Available:
PDF(144KB),
Compressed Postscript(68KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Energy Efficient Prefetching and Caching.
In
Proceedings of the USENIX 2004 Annual Technical Conference (USENIX'04),
June 27-July 2, 2004, pp. 255--268, Boston Marriott Copley Place, Boston, MA, USA.
Available:
PDF (176KB),
Compressed Postscript (92KB).
Slides:
PDF (144KB),
Compressed Postscript (383KB).
Handouts:
PDF (92KB),
Compressed Postscript (316KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Energy Efficiency through Burstiness.
In
Proceedings of the 5th IEEE Workshop on Mobile Computing Systems and Applications
(WMCSA'03), October 9-10, 2003, pp. 44--53, Monterey, California, USA.
Available:
PDF (272KB),
Compressed Postscript (116KB).
Slides: PDF(128 KB).
Handouts: PDF(120 KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Increasing Disk Burstiness for Energy Efficiency,
Technical Report 792, University of Rochester, November 2002.
Available:
PDF(224KB),
Compressed Postscript(112KB).
Talks
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Power-efficient Server-class Performance from Arrays of Laptop Disks
Work-In-Progress presentation at the
USENIX 2004 Annual Technical Conference (USENIX'04),
June 27-July 2, 2004, Boston Marriott Copley Place, Boston, MA, USA.
Summary:
PDF(27KB),
Compressed Postscript(14KB).
Slides:
PDF(39KB),
Compressed Postscript(200KB).
Handouts:
PDF(33KB),
Compressed Postscript(192KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Energy Efficient Prefetching and Caching.
In
Proceedings of the USENIX 2004 Annual Technical Conference (USENIX'04),
June 27-July 2, 2004, Boston Marriott Copley Place, Boston, MA, USA.
Available:
PDF (176KB),
Compressed Postscript (92KB).
Slides:
PDF (144KB),
Compressed Postscript (383KB).
Handouts:
PDF (92KB),
Compressed Postscript (316KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Energy Efficient Prefetching and Caching.
Poster Paper Presentation at the
19th ACM Symposium on Operating Systems Principles (SOSP'03),
The Sagamore, Bolton Landing (Lake George), New York, October 19-22, 2003.
Abstract:
PDF(80KB),
PS(66KB).
Poster:
Poster in PowerPoint (40x32 inches)(144KB).
Poster in PDF (A4 size)(50KB).
Poster in Compressed PS (A4 size)(224KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott
Energy Efficiency through Burstiness.
Paper presentation at the
5th IEEE Workshop on Mobile Computing Systems and Applications
(WMCSA'03), October 9-10, Monterey, California, USA.
Also available:
Slides in PDF(128 KB).
Handous in PDF(120 KB).
-
Athanasios E. Papathanasiou
and
Michael L. Scott:
Increasing File System Burstiness for Energy Efficiency.
Work In Progress Presentation at the
5th Symposium on Operating Systems Design and Implementation
(OSDI'02),
Boston, MA, December 2002.
Also Available:
Slides in PDF(33KB),
Handouts in PDF(30KB).
Acknowledgments
This work is supported in part by NSF grant CNS-0411127. Any opinions,
findings, and conclusions or recommendations expressed in this material
are those of the author(s) and do not necessarily reflect the views of
the National Science Foundation.
Keywords: file systems, energy efficiency, power efficiency,
energy-aware operating systems, prefetching and update policies