CS194-3/CS16x
Introduction to Systems
Lecture 27
Course Wrap-up and Various Topics
December 5, 2007
Prof. Anthony D. Joseph
http://www.cs.berkeley.edu/~adj/cs16x
Goals for Today
• Course wrap-up
• Various topics
Note: Some slides and/or pictures in the following are
adapted from slides ©2005 Silberschatz, Galvin, and Gagne.
Slides courtesy of Kubiatowicz, AJ Shankar, George Necula,
Alex Aiken, Eric Brewer, Ras Bodik, Ion Stoica, Doug Tygar,
and David Wagner.
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Course Summary
• You’ve gained a basic knowledge of systems,
networking, databases, security, and software
engineering problems, challenges, and solutions
– And, you’ve worked with a large-scale codebase and built
two real-world applications
– But, there’s a lot more!
– Take CS 162, CS 186, CS 169, EE 122, CS 161
• Some common themes:
– Complexity, modularity, abstractions, layering, SW flaws
– Dealing with large systems and groups is very hard!
• Methods:
– Programming and documentation style, E2E arguments
– Project team organization, IDEs, testing, and other tools
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Course Summary
• Database relational model, SQL
– ACID model, query operators
– Information Retrieval: Boolean search
• Programming parallel and distributed systems
– Processes and threads: “Building a Thread System”
– Concurrency control in languages, systems, and DBMSs:
» Mutual exclusion, semaphores, condition variables, monitors
– Serializability, conflict serializability, 2PL and strict
2PL, 2PC, logging, recovery, deadlock
– “Programming with MapReduce”
• Operating Systems
– Kernel and address spaces
– Address translation, caching, TLBs, and demand paging
– Memory management policies in DBMSs and OSs
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Course Summary
• I/O Systems
– Disk management, file systems, naming, directories
– File system organization and DBMS indexing (B+ trees)
• Networking
– Architectures, layering, protocols (UDP and TCP), flow
control, congestion control
– “Building a Peer-to-Peer Application”
• Computer and network security
– Cryptosystems, viruses, worms, firewalls, VPNs
• Post-graduation? Consider continuing education,
extension, …
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Some Topics People Requested
• User Interface design
• Computing for developing
nations
• Sensor networks
• Web programming
• Dragons
– No, not really…
– But, here is a Chinese
dragon from Wikipedia
• And the topic is…
• Datacenter is the Computer
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Datacenter is the Computer
• Google program == Web search, Gmail,…
• Google computer ==
– Thousands of computers, networking, storage
• Warehouse-sized facilities and workloads may be
unusual today but are likely to be more common in
the next few years
(From Luiz Barroso’s talk at Berkeley)
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Datacenter is the Computer
• Orders of magnitude more devices
(CPU’s/rack, Number of racks/managed facility)
• 1980’s: Bank of America datacenter ≈20 IBM
370 mainframes ≈100 CPU’s, ≈100 disks
• 1995: Network of Workstations-1 ≈100 CPUs,
200 disks; NOW-2 ≈1000 CPUs, 2000 disks
• 2000: Inktomi ≈ 10,000 nodes in 4 DCs
• 2005: Google ≈ 450,000 Nodes in ≥ 25 DC*
• Computer Architecture == Architecture!
• What should be the basic “building” block?
*John Markoff, “Google's not-so-very-secret weapon,” NY Times, 6/13/06
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Datacenter is the Computer
• A datacenter composed of 20 ft. containers
– Power/cooling for 200 KW of racked HW
– External taps for electricity, network, water
• 250 Servers, 7 TB DRAM, or 1.5 PB disk
– Up to 2,000 cores, providing 8,000 simultaneous
processing threads
Project Blackbox
10/17/06
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Sun’s Project BlackBox
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Sun’s Project BlackBox
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Sun’s Project BlackBox
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Sun’s Project BlackBox
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BREAK
Datacenter is the Computer
Datacenter
10G Ethernet
Edge Servers
Desktop
PCs
Wireless
Infrastructure
PDAs
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Cell Phones
Future Devices
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Datacenter is the Computer
• Re-inventing Client/Server Computing (and the web)
• The Datacenter is the (Server) Computer
• The Handheld is the (Client) Computer
– Dell ships more laptops than desktops in 2008?
• Intel's Otellini Keynote: “Digital Convergence,
Wireless Will Help Buoy Industry” 10/12/2006
– He and others at Intel demonstrated prototype "Universal
Communicator“ – combo cell phone, PC, and video device
that transfers real-time video, voice and data wirelessly
• But, how to make a limited capability mobile device
equal a wired, always-on desktop??
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Datacenter is the Computer
• Key insight:
– Enable “weak/limited” end devices to use (wireless)
networking to leverage powerful infrastructure resources
– Examples:
» Smartphones: Google web search, Microsoft Live Search,
Apple iPhone web applications
» Google Apps versus Microsoft Office
» Others?
• Use “Web Services” as library functions for apps
– Ruby on Rails, Ajax, XML, SOAP
– MapReduce (Hadoop), Chubby distributed lock manager
• Use Web Services for application storage
– E.g., Amazon Simple Storage Service (S3) and Elastic
Computing (EC2), Google FS, Bigtable
» Smugmug (≈ Flickr) saves $0.5M/yr using Amazon S3
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One Laptop Per Child (OLPC)
• Limited capabilities
– 433 Mhz AMD x86 CPU
– 256 MB RAM
– 1 GB NAND Flash
» No disk drive
– 802.11b/g WiFi
– 7.5” dual-mode TFT
display
» Grayscale reflective
1200x900
» Color 800x600
– Color video camera
• Ultra low-cost: $200
• But, how to network in
the 3rd world?
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OLPC Uses Mesh Networking to Reach Infrastructure
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Unmanned Airborne Vehicles (UAV) as Rapidly
Deployable Airborne Radio Networks?
• Stratellite statistics:
– 245 ft length, 145 ft width,
87 ft height, 1.3 million ft3
– Solar cells power electric
motors
– Payload capacity: 3,000 lbs
– Maximum altitude: 70,000 ft
– LoS to a 300,000 sq mile area
– Wireless reach to 200 mile
radius
– Maximum duration: 18 months
– But, not yet commercially
available/feasible
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Stratellite
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Administrivia
• Project 3 code due Thursday 12/6
• Midterm 3 Exam is Monday 12/10
• In-class 9-10:45
• Course survey followed by exam
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Sensor Networking Wireless Vision
Asset Tracking
Military Scenarios
Home Automation
Security
A symphony of embedded devices!!
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UCB 1st Generation Sensor ‘Mote’
COTS Dust
weC Mote
• 4Mhz, 8bit MCU (ATMEL)
512 bytes RAM, 8K ROM
• 900Mhz Radio (RF
Monolithics)
10-100 ft. range
• Temperature Sensor
• Light Sensor
• LED outputs
• Serial Port
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UCB 2nd Generation Sensor ‘Mote’
• Two Board Sandwich
– Main CPU board with
Radio Communication
– Secondary Sensor
Board
• Allows for expansion and
customization
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Current sensors include: Acceleration,
Magnetic Field, Temperature, Pressure,
Humidity, Light, and RF Signal Strength.
Can control RF transmission strength & Sense
Reception Strength
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UCB Sensor Mote Design Lineage
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COTS dust prototypes (Kris Pister et al.)
weC Mote (~30 produced)
Rene Mote (850+ produced)
Dot (1000 produced)
Mica node (1800+ produced)
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?
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Multi-Hop Routing Demo
• Sensors automatically assemble and determine routing topology
– Parallel Breadth First Search
– Shortest path to all nodes remembered
• Base station broadcasts out routing information
• Individuals listen for and propagate route update
– N messages sent
• Generational scheme to prevent cycles in routing table
Base
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Cory Energy Monitoring/Mgmt System
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50 nodes on single floor
5 level ad hoc net
30 sec sampling
250K samples to database over 6 weeks
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Structural Performance due to Multi-Directional
Ground Motions (Glaser & CalTech)
Mote
Layout
Mote infrastructure
Comparison of Results
Wiring for traditional
structural instrumentation
+ truckload of equipment
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Vehicle Tracking
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UAV-based Sensor Network Deployment
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Summary
• Datacenter is the computer!
• Many benefits
– Centralized, robust resources
– Amortize costs across tens of millions of users
– Simple, low cost devices can leverage billion dollar
investments
• Many issues
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Dependence on network connectivity
One outage affects many users
Insufficient power resources for datacenters
Data privacy
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