Systems Architecture, Fifth Edition

Module 2 - SystemsMIS5122: Enterprise Architecture for IT AuditorsAgendaSystems TopicsCentral Processing Unit (CPU)Control UnitArithmetic Logic Unit (ALU)RegistersThe System BusI/O BasicsProcessing ParallelismMulticore ProcessingScaling up & outClass ActivityBuilding our own computer (No, not LMC!)

Case Study Focus on Systems

DesktopsServersSpecial Purpose MachinesNASRoutersQuestion?Is a 2.4 GHz Xeon twice as fast as a 1.2 GHz Pentium III?Is a 3.4 GHz Xeon twice as fast as a 1.7 GHz Xeon?Will my program run in half the time on the 3.4 GHz Xeon vs. the 1.7 GHz Xeon?5

Control unitMoves data and instructions between main memory and registersTells the ALU what to do

Arithmetic logic unit (ALU)Performs computation and comparison operationsAll input and output to registers

Set of registersStorage locations that hold inputs and outputs for the ALU

How a Microprocessor WorksRegistersWhat are general-purpose registers?What are special-purpose registers?

General Purpose Registers - Hold data for currently executing program that is needed quickly or frequently

Hold intermediate results and frequently needed data itemsUsed only by currently executing programImplemented within the CPU; contents can be read or written quicklyIncreasing their number usually decreases program execution time to a point

Special Purpose Registers - Store information about currently executing program and about status of CPUTrack processor and program statusTypesInstruction registerInstruction pointerProgram status word (PSW)Stores results of comparison operationControls conditional branch executionIndicates actual or potential error conditionsWord SizeWhat is the word size of a machine?

Word SizeNumber of bits a CPU can process simultaneously

Increasing it usually increases CPU efficiency, up to a point

Other computer components should match or exceed it for optimal performance CPU components (ALU, registers), bus, RAM, etc.

Implications for system bus design and physical implementation of memory9

What did you learn?A(n) _______ is the number of bits processed by the CPU in a single instruction. It also describes the size of a single register.

The address of the next instruction to be fetched by the CPU is held in the _______________.

wordinstruction pointerWhat did you learn?In many CPUs, a register called the _____ stores condition codes, including those representing processing errors and the results of comparison operations.

PSWClock RateWhat is the clock rate of a machine?How is it typically measured?What is the CPU cycle time?What are wait states?Typically measured in thousands of MHz(1000 MHz = 1 GHz)CPU cycle time inverse of clock rateCan typically fetch and execute simple instruction in 1 cycleRate of actual or average instruction execution is measured in MIPS or MFLOPSWait stateWaiting to access memoryWaiting to access I/O devices

What did you learn?The _________ time of a processor is 1 divided by the clock rate (in Hz).

One ______ is one cycle per second.

cycle timehertzQuestion?In your own words, what does Moores law have to do with making CPUs faster?The Physical CPUElectrical device implemented as silicon-based microprocessorContains millions of switches, which perform basic processing functionsPhysical implementation of switches and circuits Why binary?

What is the decimal system and why do we use it?

How would we count if we had four fingers on each hand?

Binary is just another numbering system, no better or worse than decimalUse binary numbers to represent numeric valuesUse binary numbers to represent characters

Favorite sayingThere are 10 types of people in this world, those who understand binary and those who dont

Its cheap and easy to make circuits that deal with two and only two voltagesHigh voltage represents a 1Low voltage represents a 0Switches and GatesWhat are switches and gates?Basic building blocks of computer processing circuits

Electronic switchesControl electrical current flow in a circuitImplemented as transistors

GatesAn interconnection of switchesA circuit that can perform a processing function on an individual binary electrical signal, or bit

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NotAndOrXOrNAnd

XOrXOrXOrXOrAndAndAndABCarrySum0000100101011110

Look at the physical length of the circuit and were only adding a pair of 6 bit numbers. How long would the circuit be if we were multiplying a pair of 32 bit numbers or 64 bit numbers?Electrical PropertiesAffect speed and reliability of CPUConductivityAbility of an element to enable electron flowResistanceLoss of electrical power that occurs within a conductorHeatNegative effects of heat:Physical damage to conductorChanges to inherent resistance of conductorDissipate heat with a heat sinkSpeed and circuit lengthTime required to perform a processing operation is a function of length of circuit and speed of light(approx 186,000 miles per second)Reduce circuit length for faster processing22Moores Law - Rate of increase in transistor density on microchips doubles every 18-24 months with no increase in unit cost

What did you learn?___________ predicts that transistor density and processor power will double every two years or less.

Moores lawCase Study The Fastest CPUs?

ServersA few special purpose desktops?

The System BusSystem Bus (FSB)Connects CPU with main memory and peripheral devices

Set of data lines, control lines, and status linesData busAddress busControl bus

Bus protocolNumber and use of linesProcedures for controlling access to the busThe System BusQuestion?If I have one system with an 800 MHz bus and another system with a 1.6 GHz bus, will the second system run application twice as fast as the first system?

Load R1,10001000Read from RAMAnd wait for 1 bus cycle127.34AddressData1000127.34Subtotal10010.07Tax rate1002TaxRegisterValueR1R2127.34

Load R2,10011001Read from RAMAnd wait for 1 bus cycle0.07AddressData1000127.34Subtotal10010.07Tax rate1002TaxRegisterValueR1R2127.340.07

Multiply R1,R2And wait for 1 clock cycleAddressData1000127.34Subtotal10010.07Tax rate1002TaxRegisterValueR1R2127.340.078.91

Store R2,10021002Store into RAMAnd wait for 1 bus cycle8.91AddressData1000127.34Subtotal10010.07Tax rate1002TaxRegisterValueR1R2127.348.918.91Bus Clock and Data Transfer RateWhat is the bus clock pulse and a bus cycle?

What do these have to do with data transfer rate?Bus clock pulseCommon timing reference for all attached devicesFrequency measured in MHz

Bus cycleTime interval from one clock pulse to the next

Data transfer rateMeasure of communication capacityBus capacity = data transfer unit x clock rate

Case Study The Fastest FSBs?

ServersA few special purpose desktops?What did you learn?The ___________ is the communication channel that connects all computer system components.

The system bus can be decomposed logically into three sets of transmission lines: the _______bus, the ________ bus, and the ____ bus.

system busaddresscontroldataBreak TimeQuestion?What does it mean when I say that a device controller insulates the system from the physical geometry of I/O devices?How do device controllers insulate the system from the physical geometry of I/O devices?Key to Annes Filing System?What the heck was the key to Annes filing system?Why was the white paper on Oracle Datagard filed in the potato salad folder?Why were the hardware lease prices filed with dry cleaning receipts?I didnt know and I didnt care (OK, at first it drove me crazy).Id give her a request for informationthe information would magically appear on in my in-box.

Logical Access I/O PortsWhat is meant by logical access and how do I/O ports facilitate logical access?Communication pathway from CPU to/from peripheral device

Usually a memory address that can be read/written by the CPU and a single peripheral device

Also a logical abstraction that enables CPU and bus to interact with each peripheral device as if the device were a storage device with linear address space

Mailbox analogy

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Logical access: The device, or its controller, translates linear sector address into corresponding physical sector location on a specific track and platter.40

Device ControllerUsed by secondary storage and I/O devices

Implement the bus interface and access protocols

Translate logical addresses into physical addresses

Enable several devices to share access to a bus connection

What did you learn?A(n) ________ is a memory address to which the CPU copies data when writing to an I/O or storage device.

The operating system normally views any storage device as a(n) _________________, thus ignoring the device's physical storage organization.

I/O portLinear address spaceWhat did you learn?Part of the function of a storage secondary device controller is to translate _______________ into physical addresses.

logical addressesQuestion?What are the big differences between buffers and caches?Buffers and CachesWhat is a buffer and what is a cache? How are they similar? How are they different?Improve overall computer system performance by employing RAM to overcome mismatches in data transfer rate and data transfer unit size

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BufferMailman/mailbox analogy

Small storage areas (usually DRAM or SRAM) that hold data in transit from one device to another

Use interrupts to enable devices with different data transfer rates and unit sizes to efficiently coordinate data transfer

Buffer overflow

Intel Itanium 2 microprocessor uses three levels of primary storage caching.Can limit wait states by using SRAM cached between CPU and SDRAM primary storage:Level one (L1): within CPULevel two (L2): on-chipLevel three (L3): off-chipCacheDiffers from buffer:Data content not automatically removed as usedUsed for bidirectional dataUsed only for storage device accessesUsually much largerContent must be managed intelligently

Achieves performance improvements differently for read and write accesses

Case Study The Largest Caches?

ServersA few special purpose desktops?What did you learn?A(n) _______ is a small area of memory used to resolve differences in data transfer rate or data transfer unit size.

A(n) ______ is an area of fast memory where data held on a storage device is prefetched in anticipation of future requests for that data.

buffercacheWhat did you learn?A(n) ____ cache is implemented on the same chip as the CPU and is integrated into the same circuitry as the CPU.

L1Processing ParallelismIncreases computer system computational capacity; breaks problems into pieces and solves each piece in parallel with separate CPUsTechniquesMulticore processorsMulti-CPU architectureClusteringQuestion?What type of system is faster?A 4-way system with four separate CPUsA quad-core system

Multicore ProcessorsInclude multiple CPUs and shared memory cache in a single microchip

Typically share memory cache, memory interface, and off-chip I/O circuitry among the cores

Reduce total transistor count and cost and provide synergistic benefits

Case Study Multiple Processors or Multicore Processors?

ServersA few special purpose desktops?Multi-CPU ArchitectureEmploys multiple single or multicore processors sharing main memory and the system bus within a single motherboard or computer systemCommon in midrange computers, mainframe computers, and supercomputersCost-effective forSingle system that executes many different application programs and servicesWorkstationsScaling UpWhat is scaling up?Increasing processing by using larger and more powerful computers

Used to be most cost-effective

Still cost-effective when maximal computer power is required and flexibility is not as important

Scaling OutWhat is scaling out?Partitioning processing among multiple systems

Speed of communication networks; diminished relative performance penalty

Economies of scale have lowered costs

Distributed organizational structures emphasize flexibilityImproved software for managing multiprocessor configurations

57Computer System ClassesMicrocomputerMeets information processing needs of single userExamples: PCs, network computersPortableMeets information processing needs of a single user at a variety of levelsExamples: laptop, network, PDAMidrange computerSupports many programs and users simultaneouslyMainframeHandles information processing needs of large number of users and applicationsLarge amounts of data storage and accessSupercomputerDesigned for rapid mathematical computation58

Table 2.2 Representative products in various computer classes (2009)Multicomputer ConfigurationsAny organization of multiple computers to support a specific set of services or applicationsCommon configurationsClusterBladeGridCouldClusterGroup of similar or identical computers that cooperate to provide services or execute a common applicationConnected by high-speed networkTypically located close to one anotherAdvantages: scalability and fault toleranceDisadvantages: complex configuration and administrationBladeCircuit board that contains most of a serverSame advantages and disadvantages as a cluster, but also:Concentrate more computing power in less spaceAre simpler to modifyGridGroup of dissimilar computer systems, connected by high-speed network, that cooperate to provide services or execute a common applicationComputers may be in separate rooms, buildings, or continentsComputers work cooperatively at some times, independently at othersCloudSet of computing resources with two components:Front-end interfacesBack-end resourcesSpecific way of organizing computing resources for maximum availability and accessibilityMinimum complexity in the user or service interfaceCase Study Focus on Systems

DesktopsServersSpecial Purpose MachinesNASRoutersReviewSystems TopicsCentral Processing Unit (CPU)Control UnitArithmetic Logic Unit (ALU)RegistersThe System BusI/O BasicsProcessing ParallelismMulticore ProcessingScaling up & out`

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