04.ConcurrentProgrammingOverview

04.ConcurrentProgrammingOverview - ConcurrentPrograming:

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1 Concurrent Programing: Why you should care, deeply
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2 Student Questions 1. it is said that user-level threads are implemented by a library at  the user-level. we have POSIX for starting user threads in C++.  How do I start a kernel thread?  2. we all know that creating a kernel thread is more expensive than  creating a user thread. can you explain more about _how_ it is  expensive?  System call 1,000s of cycles Function call 10s of cycles 3. Why is creating a process more expensive than creating a kernel  thread?
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3 Uniprocessor Performance Not Scaling 1 10 100 1000 10000 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 Performance (vs. VAX-11/780) 25% /year 52% /year 20% /year Graph by Dave Patterson
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4 Power and heat lay waste to processor makers Intel P4 (2000-2007) 1.3GHz to 3.8GHz, 31 stage pipeline “Prescott” in 02/04 was too hot. Needed 5.2GHz to beat 2.6GHz Athalon Intel Pentium Core, (2006-) 1.06GHz to 3GHz, 14 stage pipeline Based on mobile (Pentium M) micro-architecture Power efficient 2% of electricity in the U.S. feeds computers Doubled in last 5 years
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5 What about Moore’s law? Number of transistors double every 24 months Not performance!
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6 Architectural trends that favor multicore Power is a first class design constraint Performance per watt the important metric Leakage power significant with small transisitors Chip dissipates power even when idle! Small transistors fail more frequently Lower yield, or CPUs that fail? Wires are slow Light in vacuum can travel ~1m in 1 cycle at 3GHz Motivates multicore designs (simpler, lower-power cores) Quantum effects Motivates multicore designs (simpler, lower-power cores)
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7 Multicores are here, and coming fast! Sun Rock
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This document was uploaded on 03/09/2012.

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04.ConcurrentProgrammingOverview - ConcurrentPrograming:

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