Load Instr 1. Instr 2 Instr 3. Instr 4. Outline & Announcements. EEL-4713C Computer Architecture Pipelined Processor - Hazards

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1 uli & Aoucm EEL-4713C Compu Achicu Pipli Poco - Haza oucio o Haza Fowaig 1 cycl Loa Dlay 1 cycl Bach Dlay Wha mak pipliig ha EEL4713C A Goo-Ro.1 EEL4713C A Goo-Ro.2 Pipliig alig wih haza Sigl Mmoy i a Sucual Haza Limi o pipliig: Haza pv x iucio fom xcuig uig i iga clock cycl ucual haza: HW cao uppo hi combiaio of iucio aa haza: iucio p o ul of pio iucio ill i h pipli cool haza: pipliig of bach & oh iucio ha chag h PC Commo oluio i o all h pipli uil h haza i olv, iig o o mo bubbl i h pipli. Loa Tim (clock cycl) Mm Rg Mm Rg Mm Rg Mm Rg Mm Mm Rg Mm Rg Rg Mm Rg Mm Rg Mm Rg EEL4713C A Goo-Ro.3 EEL4713C A Goo-Ro.4

2 pio 1: Sall o olv Mmoy Sucual Haza Tim (clock cycl) pio 2: Duplica o Rolv Sucual Haza Spaa ucio Cach (m) & Daa Cach (Dm) Tim (clock cycl). Loa 1 Mm Rg Mm Rg Mm Rg Mm Rg. Loa 1 2 3(all) 4 Mm Rg Mm Rg bubbl Mm Rg Mm Rg Mm Rg Mm Rg m Rg Dm Rg EEL4713C A Goo-Ro.5 EEL4713C A Goo-Ro.6 Daa Haza o 1 Daa Haza o 1: a 1,2,3 ub 4, 1,3 a 6, 1,7 o 8, 1,9 xo 10, 1,11. Dpci backwa i im a haza Tim (clock cycl) F D/RF EX MEM WB a 1,2,3 ub 4,1,3 a 6,1,7 o 8,1,9 xo 10,1,11 m Rg Dm Rg EEL4713C A Goo-Ro.7 EEL4713C A Goo-Ro.8

3 pio1: HW Sall o Rolv Daa Haza Bu call how h cool logic wok. Tim (clock cycl) F D/RF EX MEM WB a 1,2,3 ub 4, 1,3 a 6,1,7 o 8,1,9 xo 10,1,11 m bubbl bubbl bubbl Rg Dm Rg m Rg Dm m Rg m Rg Th Mai Cool ga h cool igal uig Rg/Dc F/D Rgi Cool igal fo Exc (Exp, Sc,...) a u 1 cycl la Cool igal fo Mm (MmW Bach) a u 2 cycl la Cool igal fo W (MmoRg MmW) a u 3 cycl la Rg/Dc Exc Mm Mai Cool Exp Sc p RgD MmW Bach MmoRg RgW D/Ex Rgi Exp Sc p RgD MmW Bach MmoRg RgW Ex/Mm Rgi MmW Bach MmoRg RgW Mm/W Rgi W MmoRg RgW EEL4713C A Goo-Ro.9 EEL4713C A Goo-Ro.10 pio 1: HW all pipli pio 2: SW i ip iucio. HW o chag PC => kp fchig am iucio & cool igal o big valu (0) Tim (clock cycl) F D/RF EX MEM WB a 1,2,3 all all all ub 4,1,3 m bubbl bubbl bubbl bubbl m bubbl bubbl bubbl bubbl m bubbl bubbl bubbl bubbl. Wo ca i NP iucio Tim (clock cycl) F D/RF EX MEM WB a 1,2,3 op op op ub 4,1,3 m Rg Dm Rg a 6,1,7 m Rg Dm a 6,1,7 m Rg Dm EEL4713C A Goo-Ro.11 EEL4713C A Goo-Ro.12

4 . pio 3 igh: Daa i availabl! Pipli gi alay coai aa Tim (clock cycl) F D/RF EX MEM WB a 1,2,3 ub 4,1,3 a 6,1,7 o 8,1,9 xo 10,1,11 m Rg Dm Rg HW Chag fo Fowaig (Bypaig):) ca muliplx o a pah fom pipli gi EEL4713C A Goo-Ro.13 EEL4713C A Goo-Ro.14 Loa lay Fowaig uc Daa Haza o 1 cycl: Cycl 1 Cycl 2 Cycl 3 Cycl 4 Cycl 5 Cycl 6 Cycl 7 Cycl 8 Clock 0: Loa fch Rg/Dc Exc Mm W Plu 1 fch Rg/Dc Exc Mm W Plu 2 fch Rg/Dc Exc Mm W Plu 3 fch Rg/Dc Exc Mm W Plu 4 fch Rg/Dc Exc Mm W Alhough Loa i fch uig Cycl 1: Daa loa fom mmoy i cycl 4 Th aa i NT wi io h Rg Fil uil h of Cycl 5 W cao a hi valu fom h Rg Fil uil Cycl 6 3-iucio lay bfo h loa ak ffc. Tim (clock cycl) F D/RF EX MEM WB lw 1, 0(2) ub 4,1,6 a 6,1,7 o 8,1,9 m Rg Dm Rg EEL4713C A Goo-Ro.15 EEL4713C A Goo-Ro.16

5 pio1: HW Sall o Rolv Daa Haza Chck fo haza & all pio 2: SW i ip iucio Wo ca i NP iucio. Tim (clock cycl) F D/RF EX MEM WB lw 1, 0(2) all ub 4,1,3 a 6,1,7 o 8,1,9 m bubbl bubbl bubbl bubbl m Rg Dm Rg. Tim (clock cycl) F D/RF EX MEM WB lw 1, 0(2) op ub 4,1,3 a 6,1,7 o 8,1,9 m Rg Dm Rg EEL4713C A Goo-Ro.17 EEL4713C A Goo-Ro.18 *Sofwa Schulig o Avoi Loa Haza *Sofwa Schulig o Avoi Loa Haza Ty poucig fa co fo a = b + c; = f; aumig a, b, c,,, a f i mmoy. Slow co: LW Rb,b LW Rc,c ADD Ra,Rb,Rc SW a,ra LW R, LW Rf,f SUB R,R,Rf SW,R EEL4713C A Goo-Ro.19 Ty poucig fa co fo a = b + c; = f; aumig a, b, c,,, a f i mmoy. Slow co: LW Rb,b LW Rc,c ADD Ra,Rb,Rc SW a,ra LW R, LW Rf,f SUB R,R,Rf SW,R EEL4713C A Goo-Ro.20 all all

6 Sofwa Schulig o Avoi Loa Haza Compil Avoiig Loa Sall: Ty poucig fa co fo a = b + c; = f; aumig a, b, c,,, a f i mmoy. Slow co: LW Rb,b LW Rc,c ADD Ra,Rb,Rc SW a,ra LW R, LW Rf,f SUB R,R,Rf SW,R EEL4713C A Goo-Ro.21 Fa co: LW Rb,b LW Rc,c LW R, ADD Ra,Rb,Rc LW Rf,f SW a,ra SUB R,R,Rf SW,R chul uchul gcc 31% 54% pic 14% 42% x 25% 65% 0% 20% 40% 60% 80% % loa allig pipli EEL4713C A Goo-Ro.22 Bach lay Cycl 4 Cycl 5 Cycl 6 Cycl 7 Cycl 8 Cycl 9 Cycl 10 Cycl 11 Clk 12: Bq fch Rg/Dc Exc Mm W (ag i 1000) 16: R-yp fch Rg/Dc Exc Mm W 20: R-yp fch Rg/Dc Exc Mm W 24: R-yp fch Rg/Dc Exc Mm W 1000: Tag of B fch Rg/Dc Exc Mm W Alhough Bq i fch uig Cycl 4: Tag a i NT wi io h PC uil h of Cycl 7 Bach ag i NT fch uil Cycl 8 3-iucio lay bfo h bach ak ffc Bach Sall mpac f CP = 1, 30% bach, Sall 3 cycl => w CP = 1.9! 2 pa oluio: Dmi bach ak o o oo, AND Compu ak bach a ali MPS bach = 0 o!= 0 Soluio pio 1: Mov Zo o D/RF ag A o calcula w PC i D/RF ag 1 clock cycl paly fo bach v. 3 EEL4713C A Goo-Ro.23 EEL4713C A Goo-Ro.24

7 pio 1: mov HW fowa o uc bach lay pio 2: Dfi Bach a Dlay Nx PC A ucio Fch 4 A Mmoy F/D. Dco Rg. Fch Nx SEQ PC A RS1 RS2 MUX Zo? Rg Fil D/EX Excu A. Calc MUX EX/MEM Mmoy Acc Daa Mmoy MEM/WB Wi Back MUX A iucio af bach ha o xcu ip of h bach oucom Wo ca, SW i NP io bach lay Wh o g iucio o fill bach lay lo? Bfo bach iucio Fom h ag a: oly valuabl wh bach Fom fall hough: oly valuabl wh o bach Compil ffciv fo igl bach lay lo: Pofilig: abou 50% of lo ufully fill Sig Ex mm RD RD RD WB Daa EEL4713C A Goo-Ro EEL4713C A Goo-Ro.26 Exampl Bach picio A 1,2,3 Bq 2, 4, ag Nx Bach o pig o a, o wap Aggiv pipli poco: Plac bach oluio a aly a poibl i pipli Byo ha, u bach picio a pculaio Simpl bach picio: Aum bach o ak, fch fom fall-hough f bach i ak, fluh pipli Tag: x Mo complx chiqu a of u: Pic ak o o ak ba o laig of pa bhavio of a bach - Kp cou ix by PC o a bach pico abl Pic ag a bfo i i calcula - Bach ag abl, alo ix by PC EEL4713C A Goo-Ro.27 EEL4713C A Goo-Ro.28

8 Bach picio Summay 5-ag pipli vii Spculaiv xcuio: Tu, bu vify Aum bach picio i coc, hav mchaim o c ohwi a fluh pipli bfo ay amag o achicual a i o (i.. gi o mmoy g coup) Pipli gi Daa a cool igal popaga vy cycl Haza cio logic a fowaig fo aa haza 1 cycl loa lay lo, R-yp ha zo lay Mov bach oluio o D ag o uc lay o 1 cycl Exampl: u h PC o look up a bach pico abl a a bach ag abl f h i a machig y fo h PC, chac a i i a bach, a chac a h icio (ak/o ak) a ag mach h picio Go aha a h x PC o b h pic o La o i h pipli, oc h bach i olv (i i a bach? Coiio aifi? Wha i h ag?), ih l h iucio ha follow i commi, o ica hm EEL4713C A Goo-Ro.29 EEL4713C A Goo-Ro.30 5-ag pipli vii Haza cio 5-ag pipli vii Haza cio: Loa? R(loa) = R,R(x)? Y: all PC, F/D, i bubbl Fowaig mux Rgi Compaio logic Fowaig mux Rgi Compaio logic EEL4713C A Goo-Ro.31 EEL4713C A Goo-Ro.32

9 5-ag pipli vii D/EX.MmRa==1 a ((D/EX.R==F/D.R) o (D/EX.R==F/D.R)) Cla cool Sigal fo EX, M, WB 5-ag pipli vii Haza cio Diabl wiig PC, F/D gi EEL4713C A Goo-Ro.33 Fowaig mux Rgi Compaio logic EEL4713C A Goo-Ro.34 Fowaig mux WB=1? Diaio g ( fo loa, ohwi) mach o of x i? Mach co x? 5-ag pipli vii Haza cio: i a bach? Tak? Y: fluh F/D gi (foc op) Exampl of oh haza Ra-af-wi (RAW) Loa follow by iucio uig am gi Rgi a mu occu af loa wi i Wi-af-wi (WAW) iv. $f0,$f2,$f4 a. $f0,$f6,$f8 a. wi mu occu af iv. Wi-af-a (WAR) Fowaig mux Rgi Compaio logic iv. $f0,$f2,$f4 a. $f2,$f4,$f6 a. wi mu occu af iv. a EEL4713C A Goo-Ro.35 EEL4713C A Goo-Ro.36

10 Wh i pipliig ha? Wh i pipliig ha? up: 5 iucio xcuig i 5 ag pipli How o op h pipli? Ra? Who cau h iup? Sag Poblm iup occuig F Pag faul o iucio fch; mialig mmoy acc; mmoy-pocio violaio D Ufi o illgal opco EX Aihmic iup MEM Pag faul o aa fch; mialig mmoy acc; mmoy-pocio violaio Complx Aig Mo a ucio A mo: Auoicm cau gi chag uig iucio xcuio Now woy abou wi haza ic wi o log la ag - Wi Af Ra (WAR): Wi occu bfo ip a - Wi Af Wi (WAW): Wi occu i wog o, lavig wog ul i gi - (Pviou aa haza call RAW, fo Ra Af Wi) Mmoy-mmoy Mov iucio Mulipl pag faul EEL4713C A Goo-Ro.37 EEL4713C A Goo-Ro.38 Wh i pipliig ha? Fi Gaio RSC Pipli ( Scala ) Floaig Poi: log xcuio im Alo, may pipli FP xcuio ui o ha ca iiia w iucio wihou waiig fo full lacy FP ucio Lacy (MPS R4000) A, Subac 4 Muliply 8 Divi 36 Squa oo 112 Nga 2 Abolu valu 2 FP compa 3 Divi, Squa Roo ak -10X o -30X log ha A Excpio? A WAR a WAW haza ic pipli a o log am lgh All iucio follow am pipli o ( aic chul ). Rgi wi i la ag Avoi WAW haza All gi a pfom i fi ag af iu. Avoi WAR haza Mmoy acc i ag 4 Avoi all mmoy haza Cool haza olv by lay bach (wih fa pah) RAW haza olv by bypa, xcp o loa ul which a olv by lay loa. Subaial pipliig wih vy lil co o complxiy. Machi ogaizaio i (lighly) xpo! EEL4713C A Goo-Ro.39 EEL4713C A Goo-Ro.40

11 Exampl Toay RSC Pipli ( Supcala ) Alpha (92): up o wo iucio p cycl floaig-poi, o ig (i-o) 7 ag (i), 10 ag (FP) MPS R3000 (88) (ig) iucio p cycl 5 ag (i) Spac Mico (91) 5 ag ucio ca b iu ou of o i pipli ( yamic chul ) Mu hal WAW, WAR haza i aiio o RAW Tomaulo, Scoboaig chiqu Mulipl iucio iu i a igl cycl ucio a quu up fo xcuio i a o buff CPffciv < 1! Cool haza olv (pculaivly) by picig bach Sigl-cycl mmoy acc i b ca (cach hi) T-hu if o go o mai mmoy Aggiv pipliig wih apily icaig co/complxiy. Dimiihig u a mo ouc a a EEL4713C A Goo-Ro.41 EEL4713C A Goo-Ro.42 Exampl NBu Alpha (98) up o 4 iucio p cycl 7 ag (i), 10 ag (FP) MPS R10000 (96) 4 iucio p cycl 5 ag (i), 10 ag (FP) Spac Ula (96) 9 ag (i, FP) 4 iucio iu p cycl Succo o Pium Po 3 uop p cycl, ou-of-o Ky iffc Dp pipli fo fa clock: 20 ag Sv ig xcuio ui v. 5 Ca ovlap iucio fom wo pogam i h pipli - Hyp-haig ; imulaou muli-haig - To ofwa, look a if i ha 2 poco EEL4713C A Goo-Ro.43 EEL4713C A Goo-Ro.44

12 Rviw: Summay of Pipliig Baic Sp Up popoioal o pipli ph; if ial CP i 1, h: Spup= Pipli ph! Clock cycl upipli 1+Pipli all cycl p iucioclock cycl pipli Haza limi pfomac o compu: ucual: mo HW ouc aa: fowaig, compil chulig cool: aly valuaio & PC, lay bach, picio caig lgh of pip ica impac of haza ic pipliig hlp iucio bawih, o lacy Compil ky o ucig co of aa a cool haza loa lay lo bach lay lo Excpio, ucio S, FP mak pipliig ha EEL4713C A Goo-Ro.45