CISC 360 Fa2009. Overview. Computational Example. Real-World Pipelines: Car Washes. Michela Taufer. Pipelined

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1 CISC 360 a2009 Ovrviw ichla Taufr Powrpoint Lctur Nots for Computr Systms: Prorammr's Prspctiv,. ryant and. O'Hallaron, Prntic Hall, CS:PP CISC 360 aʼ08 al-orld Piplins: Car ashs Computational xampl Squntial Paralll 300 ps 20 ps Combinational loic lay or latncy = 320 ps Throuhput = 3.12 GOPS Piplind 3 CISC 360 aʼ08 4 CISC 360 aʼ08

2 CISC 360 a ay Piplind Vrsion Piplin iarams 100 ps 20 ps 100 ps 20 ps 100 ps 20 ps loic loic loic C lay = 360 ps Throuhput = 8.33 GOPS Tim C C C Tim 5 CISC 360 aʼ08 6 CISC 360 aʼ08 Opratin a Piplin loic C C C Tim 100 ps 20 ps 100 ps 20 ps 100 ps 20 ps loic 7 CISC 360 aʼ08 loic C Limitations: Nonuniform lays ps 20 ps loic loic C C C Tim Throuhput limitd by slowst sta Othr stas sit idl for much of th tim Challnin to partition systm into balancd stas loic C 8 CISC 360 aʼ08 lay = 510 ps Throuhput = 5.88 GOPS

3 CISC 360 a2009 Limitations: istr Ovrhad ata pndncis loic loic loic loic loic loic Combinational loic lay = 420 ps, Throuhput = GOPS s try to dpn piplin, ovrhad of loadin ristrs bcoms mor sinificant Prcnta of clock cycl spnt loadin ristr: 1-sta piplin: 6.25% 3-sta piplin: 16.67% 6-sta piplin: 28.57% Hih spds of modrn procssor dsins obtaind throuh vry dp piplinin 9 CISC 360 aʼ08 Tim 10 CISC 360 aʼ08 ata Hazards ata pndncis in Procssors 1 irmovl $50, %ax loic loic loic C 2 addl %ax, %bx 3 mrmovl 100( %bx ), %dx C C C OP4 C Tim sult dos not fd back around in tim for nxt opration Piplinin has chand bhavior of systm sult from on instruction usd as oprand for anothr ad-aftr-writ () dpndncy Vry common in actual prorams ust mak sur our piplin handls ths proprly Gt corrct rsults inimiz prformanc impact 11 CISC 360 aʼ08 12 CISC 360 aʼ08

4 rad writ rad writ CISC 360 a2009 SQ Hardwar nw Nw SQ+ Hardwar mory rad m. writ val ata Stas occur in squnc On opration in procss at a tim mory val rad m. ata writ ddr ata xcut ch val ddr ata ch val xcut val val dst dst src src dst dst src src val val dst dst src src cod istr fil rit back icod ifun r r dst dst src src cod istr fil rit back tch incrmnt icod ifun r r tch incrmnt picod pch pval pvalc pvalp 13 CISC 360 aʼ08 14 CISC 360 aʼ08 nw Nw ddin Piplin istrs val, val _icod, _val rit back _val, _val, _dst, _dst mory m. val ata ddr ata mory m. val ata mory val val ata ddr, ata mory _icod, _ch, _val val ata ddr, ata ddr ata ch val val xcut xcut ch val xcut ch xcut ch val alu, alu alu, alu val val dst dst src src val val dst dst src src dst dst src src dst dst src src cod istr fil cod istr rit back fil icod ifun r r rit back icod ifun r r tch incrmnt tch incrmnt picod pch pval pvalc pvalp 15 CISC 360 aʼ08 val, val val, val src, src cod d_src, dst, dst icod, istr cod d_src istr fil fil icod, ifun r, r icod, ifun, tch r, r, incrmnt rit back tch incrmnt prd pstat f_ 16 CISC 360 aʼ08

5 CISC 360 a2009 Piplin Stas mory _icod, _val _icod, _ch, _val _val, _val, _dst, _dst val ata ddr, ata PIP- Hardwar rit back icod val val dst dst rad m. ata writ mory data in ddr _val _ch icod ch val val dst dst _ch ch val xcut alu, alu xcut icod ifun val val dst dst src src val, val d_src d_src cod d_src, d_src istr fil rit back cod Slct d_rval dst dst src src _val istr fil _val icod, ifun, r, r, icod ifun r r tch incrmnt f_ prd tch f_ Slct incrmnt Prdict _val _val prd 17 CISC 360 aʼ08 18 CISC 360 aʼ08 mory _icod, _val _icod, _ch, _val _val, _val, _dst, _dst val ata ddr, ata rit back icod val val dst dst rad m. ata writ mory data in ddr _val _ch dback Paths rit back icod val val dst dst rad m. ata writ mory data in ddr _val _ch icod ch val val dst dst icod ch val val dst dst ch val _ch _ch xcut alu, alu xcut xcut icod ifun val val dst dst src src icod ifun val val dst dst src src cod val, val d_src, d_src istr fil rit back cod d_src d_src Slct d_rval dst dst src src _val istr fil _val cod d_src d_src Slct d_rval dst dst src src _val istr fil _val tch icod, ifun, r, r, incrmnt f_ prd icod ifun r r tch f_ Slct incrmnt Prdict _val _val icod ifun r r tch f_ Slct incrmnt Prdict _val _val prd prd 19 CISC 360 aʼ08 20 CISC 360 aʼ08

6 CISC 360 a2009 Prdictin th icod ifun r r _icod _ch _val _icod _val Prdict Our Prdiction Straty Instr valid Nd Nd rids incrmnt Split lin yt 0 yts 1-5 Slct prd Start ftch of nw instruction aftr currnt on has compltd ftch sta Not nouh tim to rliably dtrmin nxt instruction Guss which instruction will follow covr if prdiction was incorrct 21 CISC 360 aʼ08 22 CISC 360 aʼ08 covrin from isprdiction Instr valid icod ifun r Split yt 0 r lin yts 1-5 Nd Nd rids incrmnt _icod _ch _val _icod _val Prdict Piplin monstration irmovl $1,%ax #I1 irmovl $2,%cx #I2 irmovl $3,%dx #I3 irmovl $4,%bx #I4 halt #I5 isprdictd Jump ill s branch fla onc instruction rachs sta Can t fall-throuh from val turn ill t rturn whn rt rachs writ-back sta 23 CISC 360 aʼ08 Slct prd Cycl 5 I5 24 CISC 360 aʼ08 I1 I2 I3 I4

7 CISC 360 a2009 ata pndncis: 3 Nopʼs # dmo-h3.ys x000: irmovl $10,%dx 0x006: irmovl $3,%ax 0x00c: nop 0x00d: nop 0x00: nop 0x00f: addl %dx,%ax 0x011: halt Cycl 6 [%ax] 3 Cycl 7 val [%dx] = val [%ax] CISC 360 = 3 aʼ08 ata pndncis: 2 Nopʼs # dmo-h2.ys x000: irmovl $10,%dx 0x006: irmovl $3,%ax 0x00c: nop 0x00d: nop 0x00: addl %dx,%ax 0x010: halt Cycl 6 [%ax] 3 val [%dx] = 10 rror val [%ax] = 0 26 CISC 360 aʼ08 ata pndncis: 1 Nop # dmo-h1.ys x000: irmovl $10,%dx 0x006: irmovl $3,%ax 0x00c: nop 0x00d: addl %dx,%ax 0x00f: halt Cycl 5 val [%dx] = 0 rror 27 val [%ax] = 0 CISC 360 aʼ08 [%dx] 10 _val= 3 _dst= %ax ata pndncis: No Nop # dmo-h0.ys x000: irmovl $10,%dx 0x006: irmovl $3,%ax 0x00c: addl %dx,%ax 0x00: halt Cycl 4 _val= 10 _dst= %dx _val = 3 _dst= %ax 28 CISC 360 aʼ08 val [%dx] = 0 val [%ax] = 0 rror

8 CISC 360 a2009 ranch isprdiction xampl dmo-j.ys 0x000: xorl %ax,%ax 0x002: jn t # Not takn 0x007: irmovl $1, %ax # all throuh 0x00d: nop 0x00: nop 0x00f: nop 0x010: halt 0x011: t: irmovl $3, %dx # Tart (Should not xcut) 0x017: irmovl $4, %cx # Should not xcut 0x01d: irmovl $5, %dx # Should not xcut Should only xcut first 8 instructions 29 CISC 360 aʼ08 ranch isprdiction Trac # dmo-j x000: xorl %ax,%ax 0x002: jn t # Not takn 0x011: t: irmovl $3, %dx # Tart 0x017: irmovl $4, %cx # Tart+1 0x007: irmovl $1, %ax # all Throuh Incorrctly xcut two instructions at branch tart Cycl r %ax CISC 360 aʼ08 _ch = 0 _val = 0x007 val 3 dst = %dx = 4 dst = %cx turn xampl dmo-rt.ys 0x000: irmovl Stack,%sp # Intializ stack pointr 0x006: nop # void hazard on %sp 0x007: nop 0x008: nop 0x009: call p # Procdur call 0x00: irmovl $5,%si # turn point 0x014: halt 0x020:.pos 0x20 0x020: p: nop # procdur 0x021: nop 0x022: nop 0x023: rt 0x024: irmovl $1,%ax # Should not b xcutd 0x02a: irmovl $2,%cx # Should not b xcutd 0x030: irmovl $3,%dx # Should not b xcutd 0x036: irmovl $4,%bx # Should not b xcutd 0x100:.pos 0x100 0x100: Stack: # Stack: Stack pointr quir lots of nops to avoid data hazards 31 CISC 360 aʼ08 Incorrct turn xampl # dmo-rt 0x023: rt 0x024: irmovl $1,%ax # Oops! 0x02a: irmovl $2,%cx # Oops! 0x030: irmovl $3,%dx # Oops! 0x00: irmovl $5,%si # turn Incorrctly xcut 3 instructions followin rt 5 32 CISC 360 aʼ08 r %si val = 0x0 val = 1 dst = %ax val 2 dst = %cx = 3 dst = %dx

9 CISC 360 a2009 Piplin Summary 33 CISC 360 aʼ08