CS162 Operating Systems and Systems Programming Lecture 27 ManyCore OS and Peer to peer Systems December 10 2007 Prof John Kubiatowicz http inst eecs berkeley edu cs162 Requests for Final topics Some topics people requested Dragons too big of a topic for today ManyCore Systems Parallel OSs Embedded OSs Peer to Peer Systems OceanStore Virtual reality enhancement Quantum Computing Today A couple of topics to finish from last time ManyCore Parallel OS Embedded OS realtime systems Peer to Peer Systems OceanStore Other Topics Come look for me at office hours Or any other time 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 2 Security Terms Virus A piece of code that attaches itself to a program or file so it can spread from one computer to another leaving infections as it travels Most attached to executable files so don t get activated until the file is actually executed Once caught can hide in boot tracks other files OS Worm Similar to a virus but capable of traveling on its own Takes advantage of file or information transport features Because it can replicate itself your computer might send out hundreds or thousands of copies of itself Trojan Horse Named after huge wooden horse in Greek mythology given as gift to enemy contained army inside At first glance appears to be useful software but does damage once installed or run on your computer 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 3 Security Problems Buffer overflow Condition define BUFFER SIZE 256 int process int argc char argv char buffer BUFFER SIZE if argc 2 return 1 else strcpy buffer argv 1 return 0 After attack Before attack Technique exploited by many network attacks Anytime input comes from network request and is not checked for size Allows execution of code with same privileges as running program but happens without any action from user How to prevent Don t code this way ok wishful thinking New mode bits in Intel Amd and Sun processors Put in page table says don t execute code in this page 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 4 The Morris Internet Worm The beginning of chaos Internet worm Self reproducing Author Robert Morris a first year Cornell grad student Launched close of Workday on November 2 1988 Within a few hours of release it consumed resources to the point of bringing down infected machines Techniques Exploited UNIX networking features remote access Bugs in finger buffer overflow and sendmail programs debug mode allowed remote login Dictionary lookup based password cracking Grappling hook program uploaded main worm program 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 5 Timing Attacks Tenex Password Checking Tenex early 70 s BBN Most popular system at universities before UNIX Thought to be very secure gave red team all the source code and documentation want code to be publicly available as in UNIX In 48 hours they figured out how to get every password in the system Here s the code for the password check for i 0 i 8 i if userPasswd i realPasswd i go to error How many combinations of passwords 2568 Wrong 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 6 Defeating Password Checking Tenex used VM and it interacts badly with the above code Key idea force page faults at inopportune times to break passwords quickly Arrange 1st char in string to be last char in pg rest on next pg Then arrange for pg with 1st char to be in memory and rest to be on disk e g ref lots of other pgs then ref 1 st page a aaaaaa page in memory page on disk Time password check to determine if first character is correct If fast 1st char is wrong If slow 1st char is right pg fault one of the others wrong So try all first characters until one is slow Repeat with first two characters in memory rest on disk Only 256 8 attempts to crack passwords Fix is easy don t stop until you look at all the characters 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 7 Types of Parallel Machines Symmetric Multiprocessor Multiple processors in box with shared memory communication Current MultiCore chips like this Every processor runs copy of OS Non uniform shared memory with separate I O through host Multiple processors Each with local memory general scalable network Extremely light OS on node provides simple services Scheduling synchronization Network accessible host for I O P P P P Bus Memory P M P M P M P M P M P M P M P M Host P M P M P M P M P M P M P M P M Cluster Many independent machine connected with general network Communication through messages 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Network Lec 27 8 ManyCore Chips The future is on the way Intel 80 core multicore chip Feb 2007 80 simple cores Two floating point engines core Mesh like network on a chip 100 million transistors 65nm feature size Frequency Voltage Power Bandwidth Performance 3 16 GHz 0 95 V 62W 1 62 Terabits s 1 01 Teraflops 5 1 GHz 1 2 V 175W 2 61 Terabits s 1 63 Teraflops 5 7 GHz 1 35 V 265W 2 92 Terabits s 1 81 Teraflops ManyCore refers to many processors chip 64 128 Hard to say exact boundary How to program these Use 2 CPUs for video audio Use 1 for word processor 1 for browser 76 for virus checking Something new is clearly needed Kubiatowicz CS162 UCB Fall 2007 here 12 10 07 Lec 27 9 Berkeley PARLab Parallel processors have been around for a long time So what is different now Industry is on a growth path massively parallel processors will soon be widespread Communication between cores very low overhead Challenge is still how to program them Caught attention of Berkeley and many others New research laboratory PARLab New approach vertically integrated programming environment Combine lessons of last 20 years with application driven approach Berkeley researchers from many backgrounds meeting since Feb 2005 to discuss parallelism Krste Asanovic Ras Bodik Jim Demmel Kurt Keutzer John Kubiatowicz Edward Lee George Necula Dave Patterson Koushik Sen John Shalf John Wawrzynek Kathy Yelick Circuit design computer architecture massively parallel computing computer aided design embedded hardware and software programming languages compilers scientific programming and numerical analysis 12 10 07 Kubiatowicz CS162 UCB Fall 2007 Lec 27 10 Par Lab Research Overview Easy to write correct programs that run efficiently on Imagemanycore Parallel Persona Hearing Speec o ti Retriev Browse a l Health Music h c i l al r p Dwarfs p A ns Static u c er d Pro Lay ty Parallel Libraries Efficiency Languages c n ie r c Ef Laye Legacy y Code OS h c r A 12 10 07 Parallel Frameworks Sketching Type
View Full Document
Unlocking...