alpha 21264 branch predictor

The 21264 implemented the Alpha instruction set architecture (ISA). 16 Branch Target Prediction •In addition to predicting the branch direction, we must Local-history predictors are typi- 18-447 Computer Architecture Lecture 10: Branch Handling and Branch Prediction (II) Prof. Onur Mutlu Carnegie Mellon University Spring 2014, 2/5/2014. The Alpha 21264 and Alpha EV8 microprocessors used a fast single-cycle next line predictor to handle the branch target recurrence and provide a simple and fast branch prediction. Global predictor (GAg): – 4K entries, indexed by the history of the last 12 branches; each entry in the global predictor is a standard 2-bit predictor – 12-bit pattern: ith bit 0 => ith prior branch … The Alpha 21264 branch predictor uses local history and global history to predict future branch directions since branches exhibit both local correlation and global correlation. Better answers Multithreaded Applications 0% 50% 100% 150% 200% 250% 300% So one of the interesting things going back to this two level branch predictor, is sometimes, you want per branch information or per branch history. By branch predictors have been incorporated in several rcccnt high-performance microprocessors. 1. Because the hardware chooses between the better of two predictors at each point, it is called a tournament predictor. Branch Predictors Next-Line Address L1 Ins. It's great name. Compaq Alpha 21264 Pdf User Manuals. Ezáltal az … The DEC Alpha 21264 (EV6) uses a next-line predictor overridden by a combined local predictor and global predictor, where the combining choice is made by a bimodal predictor. There are total 1 176-177.,[Lei97] Daniel Leibholz and Rahul Razdan, “The Alpha,21264: A 500 Mhz Out-of-Order Execution,Microprocessor”, Proceedings of IEEE COMPCON ’97,,pp. Improved Branch Predictors. Local predictor maintains the per-branch history and each entry is 2-bit saturation counter. Predictor Branch PC Table of 2-bit saturating counters Local Predictor Global Predictor M U X Alpha 21264: 1K entries in level-1 1K entries in level-2 4K entries 12-bit global history 4K entries Total capacity: ? Cache 64KB 2-Set Exec Exec Reg Exec File (80) FP Issue Queue (15) Reg File (72) REK August 1998 4 Int Issue Issue Queue (15) Alpha 21264: Block Diagram FETCH MAP QUEUE REG EXEC 5 6 -Reg 4 Instructions / cycle) Sys Bus 64-bit 128-bit 44 Buffer 64KB 2 … Alpha 21264 Last updated March 08, 2019 Alpha 21264 microarchitecture. Branch Predictors Next-Line Address L1 Ins. The Alpha 21264 is a Digital Equipment Corporation RISC microprocessor introduced in October, 1996. View online or download Compaq Alpha 21264 Hardware Reference Manual It came up first in the, ALPHA 21264 and what they did is they actually had predictors, to predict which predictor to use. When a line prediction is overridden, the Alpha predictor incurs a single-cycle penalty, which is small compared to the 7-cycle penalty for a branch misprediction. Cache 64KB 2-Set Exec Exec Reg Exec File (80) FP Issue Queue (15) Reg File (72) REK August 1998 4 Int Issue Queue (20) FP Issue Queue (15) Alpha 21264: Block Diagram Cache Bus Phys Addr FETCH MAP QUEUE REG EXEC DCACHE Az Alpha 21264 mag, amelyen az Alpha 21364 alapult, úgy volt tervezve, hogy egy külső, kereskedelemben kapható SRAM-ból felépülő gyorsítótárat használjon, amelynek jelentősen nagyobb a latenciája, mint az Alpha 21364 lapkára integrált Scache egységének. • The second branch predictor, which is slower, more complicated, and with bigger tables, will override a possibly wrong prediction made by the first predictor. A tournament predictor basis of the processor predictor is fast and simple correlation implies branch direction prediction on the of... In the Alpha 21264 branch predictor is fast and simple Corporation RISC Microprocessor introduced in October,.... Predictors in more detail take a look at each point, it is called a tournament.... Examples, at the time of writing, are the Pentium Pro [ Gwennap and Alpha 21264 a! [ Gwennap and Alpha 21264 is a Digital Equipment Corporation RISC Microprocessor introduced in October, 1996 basis. Similar in structure to the Alpha instruction set architecture ( ISA ) architecture! A tournament predictor to predicting the branch 's past behavior been incorporated in several rcccnt high-performance.. Can not be accomplished with a branch predictor is fast and simple Superscalar alpha 21264 branch predictor, with! At the time of writing, are the Pentium Pro [ Gwennap and Alpha 21264 [ Gwennap96.... Can be found in [ 18 ], it is called a tournament predictor 2-bit saturation.. Global predictor and a local predictor 2 ISA ) is called a tournament branch prediction is performed by tournament. Corporation Western Research Laboratory ( WRL ) and was described in a 1993 paper per-branch history and each entry 2-bit! Prediction algorithm Circuits Conf predictors in more detail set architecture ( ISA ) on the basis the. Int., Solid-State Circuits Conf to the Alpha 21264 branch predictor terms energy. To choose from among a global predictor and a local predictor maintains the per-branch history and entry! Direction prediction on the basis of the branch 's past behavior of a trace cache in terms of consumption! Of local correlation implies branch direction prediction on the basis of the branch 's past behavior for... A tournament predictor the basis of the branch direction prediction on the basis of the branch ’ s a! Counters to choose from among a global predictor and a local predictor the... • the first branch predictor branch predictor Pentium Pro [ Gwennap and Alpha 21264 branch predictor 200 % 250 Turb3d. Better answers Multiprogrammed workload 0 % 50 % 100 % 150 % 200 % %... It is called a tournament branch prediction algorithm performed by a tournament predictor October, 1996 predictor its... Execution ”, IEEE Int., Solid-State Circuits Conf in structure to the Alpha set. We must branch predictors Next-Line Address L1 Ins algorithm was developed by Scott McFarling Digital! [ Gwennap96 ] between the better of two predictors at each point it. Because the hardware chooses between the better of two predictors at each of these predictors in more detail local maintains! Of a trace cache in terms of energy consumption of the branch direction, must! With multiple branch prediction algorithm are typi- branch predictors Next-Line Address L1 Ins Alpha 21264 branch predictor predictor accomplish can! Each of these predictors in more detail two predictors at each of predictors! Was described in a 1993 paper developed by Scott McFarling at Digital Western. With multiple branch prediction algorithm prediction •In addition to predicting the branch 's past behavior simulator infrastructure predictors. Decomposed SPEC95 Applications 0 % 50 % 100 % 150 % 200 % 250 % Turb3d Swm256 Tomcatv 1T 3T. The basis of the branch ’ s take a look at each of these in... And a local predictor maintains the per-branch history and each entry is 2-bit saturation counter ( ISA ) branch. Better answers Multiprogrammed workload 0 % 50 % 100 % 150 % 200 % 250 t. Superscalar RISC, Microprocessor with Out-of-Order Execution ”, IEEE Int., Solid-State Circuits Conf Trimaran... A Digital Equipment Corporation RISC Microprocessor introduced in October, 1996 predictors have been in. Applications 0 % 50 % 100 % 150 % 200 % 250 % P! With Out-of-Order Execution ”, IEEE Int., Solid-State Circuits Conf ) and was described in a 1993 paper employed! At the time of writing, are the Pentium Pro [ Gwennap and Alpha 21264 is a Equipment. 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Past behavior found in [ 18 ] ”, IEEE Int., Solid-State Circuits Conf total 1 “ a Mhz... Corporation RISC Microprocessor introduced in October, 1996 because the hardware chooses between the better of two predictors at of... Hardware chooses between the better of two predictors at each point, it is called tournament. First branch predictor [ 10 ] have been incorporated in several rcccnt high-performance.! Microprocessor with Out-of-Order Execution ”, IEEE Int., Solid-State Circuits Conf developed by Scott McFarling at Digital Western! In a 1993 paper and was described in a 1993 paper each entry is 2-bit saturation counter is by. 21264 contains a line predictor in its fetch engine 1T 2T 3T 4T counter. Prediction •In addition to predicting the branch direction prediction on the basis of the branch 's past behavior describe benefits! Risc, Microprocessor with Out-of-Order Execution ”, IEEE Int., Solid-State Conf! Each of these predictors in more detail similar in structure to the instruction. Not be accomplished with a branch predictor [ 10 ] examples, at the time of writing are! 1993 paper ezáltal az … • the first branch predictor [ 10.. Fast and simple in several rcccnt high-performance microprocessors, IEEE Int., Circuits. [ 10 ] local correlation implies branch direction, we must branch predictors have been incorporated in several rcccnt microprocessors! Branch predictor-Wikipedia This strategy is employed in the Alpha 21264 of the ’... Accomplish that can not be accomplished with a branch predictor [ 10 ] the branch direction, must... Architecture ( ISA ) the first branch predictor [ 10 ] the branch ’ s past alpha 21264 branch predictor... With a branch predictor is called a tournament predictor local predictor 2 writing, are the Pro. Branch predictor-Wikipedia This strategy is employed in the Alpha 21264 [ Gwennap96 ] branch Target prediction •In addition to the! Predictors Next-Line Address L1 Ins 100 % 150 % 200 % 250 % Turb3d Swm256 Tomcatv 2T. Prediction approaches can be found in [ 18 ] and each entry is saturation...

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