Organisasi dan arsitektur komputer Organisasi & Arsitektur Komputer Organisasi dan arsitektur komputer Wisnu Djatmiko TM 2

Daftar Pustaka Bab 1 Organisasi & Arsitektur Komputer Wisnu Djatmiko

Daftar Pustaka Bab 2 Organisasi & Arsitektur Komputer Wisnu Djatmiko

TIK Peserta MK Arsikom dapat menjelaskan definisi CPU Time dengan 90% benar. Peserta MK Arsikom dapat menjelaskan cara mengurangi CPU Time dengan 90% benar. Peserta MK Arsikom dapat menghitung CPU time sebuah fungsi dengan 90% benar. Organisasi & Arsitektur Komputer Wisnu Djatmiko

Pokok Bahasan CPU time Organisasi & Arsitektur Komputer Wisnu Djatmiko

Architectural Development & Styles Desainer Komputer berusaha meningkatkan kinerja komputer (mengurangi "kesenjangan semantik“ antara high level vs low level) Adanya kerumitan untuk membuat sebuah mesin harus diprogram untuk dapat mengkonversikan data (lambang) menjadi kode-kode biner A (latin capital letter A) = 0041H (ASCII) Organisasi & Arsitektur Komputer

Architectural Development & Styles Banyaknya mode pengalamatan (>20 mesin VAX) menambah kompleksitas instruksi Misal mesin CISC Intel PentiumTM Organisasi & Arsitektur Komputer

Architectural Development & Styles Perlu strategi untuk mempercepat kinerja mesin Misal nya meningkatkan kecepatan clock Efek stunami : meningkatkan kompleksitas perhitungan dalam satu siklus clock. Hasil penelitian menunjukkan 80% instruksi dari sebuah program berisi : assignment statements (50%), conditional branching , dan procedure calls. Organisasi & Arsitektur Komputer

Architectural Development & Styles [Optimasi arsitektur] : mempercepat instruksi yang sering digunakan dapat mengurangi kompleksitas instruksi dan jumlah mode pengalamatan. Misal : mesin RISC (Reduced Instructions Set Computers) Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES CC (Clock Cycle) menyatakan jumlah siklus clock sebuah CPU yang digunakan untuk menyeleseikan sebuah tugas, CT (Cycle Time) menyatakan waktu yang dibutuhkan 1 clock atau f (CPU Speed). Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES CPI (jumlah rata-rata clock cycle per instruksi) dapat dihitung : Persamaan CPU time menjadi : Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES It is known that the instruction set of a given machine consists of a number of instruction categories: ALU (simple assignment and arithmetic and logic instructions), load, store, branch, and so on. where Ii is the number of times an instruction of type i is executed in the program and CPIi is the average number of clock cycles needed to execute such instruction. Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES Example : Hitung CPI untuk Mesin A yang mempunyai clock rate 200 MHz CR = 200 MHz CT = 5 nS Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES Example : Mesin A mengerjakan X dengan instruksi Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES Jika Mesin A mengerjakan program X menggunakan 100 instructions, maka CPI mesin A[X] adalah : It should be noted that the CPI reflects the organization and the ISA (instruction set architecture) of the processor while the instruction count reflects the instruction set architecture and compiler technology used. Organisasi & Arsitektur Komputer

PERFORMANCE MEASURES Organisasi & Arsitektur Komputer

What time to measure? Elapsed time, wall-clock time: actual time from start to completion depends on CPU, system, I/O, etc. often used in real benchmarks only suitable choice when I/O is included

What time to measure? CPU Time: measure/analyze CPU performance only may be suitable when machine is timeshared possibly both user and system component User CPU time is our focus for first part of course

What time to measure? Elapsed time = CPU time + Idle time usually and assuming time is accurately accounted for

Metrics of performance Different performance metrics are appropriate at different levels: Frames per second Operations per second Compiler Language Programming Application (millions) of Instructions per second – MIPS (millions) of (F.P.) operations per second – MFLOP/s ISA Cycles per second (clock rate) Cycles per Instruction Datapath Control Function Units Transistors

Relating Processor Metrics CPU execution time per program = CPU clock cycles/program X Clock cycle time = CPU clock cycles/program ÷ Clock rate (frequency) CPU clock cycles/program = Instructions/program X Clock cycles Per Instruction Clock cycles Per Instruction (CPI) is an average measurement, it depends on : ISA, the implementation, and the program measured CPI = CPU clock cycles/program ÷ Instructions/program Also, Instructions per clock cycle or IPC = 1 / CPI CPU execution time = Instructions X CPI X Clock cycle

How much work can our structure perform? For a program Q: Time = Number of executed instr * Number of cycles per instr * Time per cycle T = Nq * CPI * Tc

How to reduce T? T = Nq * CPI * Tc Make this a function of the instruction CPI goes up, but we can use an average, not the worst case Tc goes down, time to do the longes step, not the entire instruction

CPU time ---- CPI < 1 [RISC dan pipeling] Branch Prediction Modular Terstruktur Organisasi & Arsitektur Komputer