CS514: Intermediate
Course in Operating
Systems
Professor Ken Birman
Ben Atkin: TA
Lecture 27: Nov. 30
Trends in Systems
• Today is our last lecture
• Have seen a great deal of
technology
–
–
–
–
Mixture of current systems
Emerging products and systems
Technologies
Research trends
• What will we see next?
Traditional Areas
•
•
•
•
•
•
•
File systems
Communications
Naming of objects, interoperation
Security
Resource management
Transactions
Extensibility
Emerging areas
• Scalable service management
• Tools for hosting data
• Mechanisms for offloading work
from customers onto 3rd party
solution provider systems
• QoS mechanisms
• Power-aware and mobility
support
Where are the big
opportunities?
• We could review these one topic
at a time, but that might get dull
• Can we develop a methodology
for recognizing big
opportunities and “leaping in”?
Technology trends
CPU MIPS
700
600
500
400
300
200
100
0
Memory MB
LAN Mbits
5
0
-2
0
0
0
0
0
O/S
overhead
2
1
9
9
5
-2
0
0
5
9
9
-1
0
9
9
1
1
9
8
5
-1
9
9
0
WAN Mbits
Source: Scientific American, Sept. 1995
Note tremendous growth
in WAN speeds
Typical latencies
(milliseconds)
Disk I/O
1000
100
Ethernet
RPC
10
1
ATM
roundtrip
0.1
WAN
roundtrip
5
-2
0
0
0
0
0
0
2
1
9
9
5
-2
0
0
5
9
9
-1
0
9
9
1
1
9
8
5
-1
9
9
0
0.01
WAN, disk latencies are
fairly constant due to
physical limitations
O/S latency: the most expensive
overhead on LAN communication!
40
35
30
25
20
15
10
5
0
O/S
overhead in
proportional
terms
19851990
19952000
Suggests?
• Notice that revolutionary
opportunity is triggered by
technical discontinuity
• To predict a revolution…
… just identify a technology sector
about to be shaken up by a trend
that breaks the usual relationships
… predict “big things will happen”
Recent revolutions
• Internet became much faster,
more widely available
• Operating systems became
object oriented
– Enabled the Web
– Which enabled all sorts of B2B
developments people knew were
coming…
Other examples?
• For a long time, PCs were slow
and balky, but very cheap
• But around 1990 technology
gave us a fast, big PC
– Suddenly, desktop world yielded to
PC world
– Price point can trigger a
discontinuity
Other examples?
• We used to be short on memory
hence relied heavily on disks
• But around 1985 memory sizes and
cost changed the equation
• Suddenly massive caches made
sense
– Giving us ideas like log-structured file
systems and new styles of caching in
file and database systems
– A world where 100% hit rates made
sense
Looking to the future?
• Major discontinuities:
– Move from PC to PDA/telephone
hybrids
– Mobility, disconnected operation
– Emergence of huge numbers of
computing systems that need to
cooperate
– Perhaps, some form of QoS?
Want to have an impact?
• Trick is to zero in on one of these
areas
• Be an early player
– For example, get a mobile hand-held
system and start to play with it
– Lots of things in the legacy
infrastructure just aren’t right for it
• Your opportunity: fix a few of them by doing
the obvious things
• And you’ll instantly be famous!
Mobile Trends
• Nomadicity: increasingly powerful
nomadic devices
– Anticipate fusion of web browser,
telephone and also PDA functionality
– Some devices of this sort already exist –
but they remain primitive
– Low bandwidth interaction a big
obstacle right now – you can’t talk to it,
but typing without a keyboard is a pain
Mobile trends
• Communications standards
– We already are seeing widespread
use of wireless ethernet cards
– Bluetooth is the next big step:
widespread low-power
connectivity for small devices
– XML helps: data objects are
readily understood… fewer
proprietary standards
Mobile trends
• Power conservation
– Also better understood
– Flexibility: compute faster or
slower, move code or data, sleep
or run more actively
– Signal strength also a factor
Mobile trends
• Suggests a future in which
– We’ll move from place to place
with our computing context
– In a given setting, devices find the
appropriate local resources and
can talk to them
– And device is smart about when to
ship code, when to ship data
Mobile trends
• But this also points to a missing link:
exciting research opportunity
– How to do naming of objects in this new
mobile world?
• User wants a single personalized name for
resources and a single name space
• But we also need to share things
– And how to organize or structure a
nomadic or wireless environment
– Peer-to-peer and multi-peer opportunity
will be enormous
Illustrating…
• A discontinuous development
– From fixed infrastructure to mobile
wireless one
– High performance but power-aware
– Fusion of previously independent
technologies (voice, web, email)
• Stress on existing infrastructure
– We tend to adapt the existing
infrastructure to the new setting
– But a whole new approach may be
needed
Driving…
• New ideas in file systems
– How should we do file systems for
mobile and wireless systems?
• Communication
– How should we do point to point and
multicast for wireless peer-to-peer or
“ad-hoc” networks?
– Is TCP the right protocol for a wireless
connection to a server?
• The list goes on…
Dangers
• It is easy to overreach
– People tend to try to do 10 things
all at the same time…
– Need to be incremental
• Challenge?
– Picking the right first step
– The right infrastructure can enable
just about anything!
The demise of curiosity
driven research
• Computer science is less and less of
a traditional science
– In the early days, we did “curiosity
driven research”
• Solve problems mostly for fun…
– Today, we think in terms of market
demand and technology transition
– Even academic research is more and
more focused on impact
• So don’t get carried away with esoteric or
theoretical ideas…
• Build and demonstrate your technologies!
Other examples
• Until recently, we needed more and
more computing power to run even
desktop environments
• But recently, advances in PC
performance have outstripped
demand for improved performance
• Creates an opportunity to do “PC
hosting” using virtual computing
systems; end-user has a lightweight
device interface
Other examples
• Pent-up demand for network QoS
solutions is enormous
• Can we somehow evade QoS
problems associated with the
Internet?
• For example, routing
– Routing hasn’t gotten much attention lately
– As we saw, routing is rather slow and static
– Better routing could be a breakthrough
opportunity
Object orientation
• World went from
– Big clumsy objects (RPC)
– To smaller components
– To XML encodings
• Suddenly, we need to manage
massive numbers of small
components and objects
• How can we structure this new
world to behave in a predictable,
reliable manner?
The list goes on…
• Broadly, the need is for
– Progress, mostly driven by hardware
advances
– Which implies certain necessary
infrastructure changes
• But we also want
– Reliability, predictability, security
– And we need to make money doing it:
technology is no longer something people
do for its own sake
– Also want to make the world a better place
The end
• Hope you got something out of the
course!
• Appropriate spring courses
– CS414 (for those who really didn’t have
the background for 514!)
– CS513 (like 514 but security)
– CS614 (entirely journal papers and lots
of them; Ken will teach this)
– ECE 566 (wireless networks)
– ECE 572 (parallel architecture)