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Unformatted text preview: 20: intro 14 8/27/13 cs420: intro 15 Clock Speeds Increased Notice a little trick: x axis goes only to 2003! 8/27/13 cs420: intro 16 Un3l they stopped increasing! Why? 8/27/13 cs420: intro 17 Source: Herb Sutter (orig. in DDJ) 8/27/13 cs420: intro 18 Predic3on in 1999 From Shekhar Borkar, Intel, at MICRO’99 8/27/13 So, the chips were getting too hot cs420: intro 19 Predic3on in 1999 From Shekhar Borkar, Intel, at MICRO’99 8/27/13 So, the chips were getting too hot cs420: intro 20 Bill Wulf in 1978 •  William Wulf is one of the most inPluential computer scientist •  Visited IISc Bangalore around 1978.. –  When I was a grad student •  Talked about his parallel computing projects –  C.mmp –  Stated motivations: Sequential processors cannot keep getting faster forever, because of physical limitations. We need many processors working in parallel to compute faster •  But engineers kept making it go faster –  Until now 8/27/13 cs420: intro 21 Frequency and Power •  There is a cubic relationship between them! –  So, if frequency doubles, dynamic power increases 8- fold! –  Static power is still a signiPicant part of the total power •  So, frequencies stalled around 2- 3 GHz –  Which is plenty fast 8/27/13 cs420: intro 22 Power vs Frequency on a given processor Power&Consump-on&(W)& 165.00% 145.00% Intel%i7%(Nehalem)% Intel%Xeon%E5520% Intel%i7%(Sandy%Bridge)% 125.00% 105.00% 85.00% 65.00% 45.00% 1.20% 1.60% 2.00% 2.40% 2.80% 3.20% 3.60% Frequency&(GHz)& 8/27/13 cs420: intro 23 Energy vs Frequency on a given processor 1.15$ Intel$Xeon$E5520$ Normalized+Energy+ 1.10$ Intel$i7$(Nehalem)$ 1.05$ Intel$i7$(Sandy$Bridge)$ 1.00$ 0.95$ 0.90$ 0.85$ 0.80$ 0.75$ 0.70$ 1.20$ 1.70$ 2.20$ 2.70$ 3.20$ Frequency+(Ghz)+ 8/27/13 cs420: intro 24 Number of Transistors/chip? •  Well, they will keep on growing for the next ten years –  May be a bit slowly •  Current technology is 32 or 22 nanometers •  We may go to 9 or 5 nanometers feature size –  i.e. gap between two wires (as a simple dePinition) •  For comparison: –  Distance between a carbon and a Hydrogen atom is 1 Angstrom = 0.1 nanometer! –  Silicon- Silicon bonds are longer –  5 Ao lattice spacing (image: wikipedia) •  i.e. 0.5 nanometer –  So, we are close to atomic units! 8/27/13 cs420: intro 25 Consequence •  •  •  •  We will get to over 50 billion transistors/chip! What to do with them? Put more processors on a chip Beginning of the multi...
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