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I/O Devices. Connected to the Backplane bus Hard disk controllers Graphics adapters Serial I/O Sound Cards Virtual Reality Helmet Gloves Quake controller. I/O Performance. I/O Bandwidth How much data can we move from A to B/time unit How many I/O operations can we perform/time unit

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I o devices l.jpg
I/O Devices

  • Connected to the Backplane bus

    • Hard disk controllers

    • Graphics adapters

    • Serial I/O

    • Sound Cards

    • Virtual Reality

      • Helmet

      • Gloves

      • Quake controller


I o performance l.jpg
I/O Performance

  • I/O Bandwidth

    • How much data can we move from A to B/time unit

    • How many I/O operations can we perform/time unit

  • Latency per access

    • Low long do we have to wait to get access

  • Response time

    • The total time to perform a task


Disk i o performance l.jpg
Disk I/O Performance

  • Supercomputer Benchmarks

    • Batch jobs

      • Large files

      • Throughput of data

  • Transaction Processing

    • I/O Rate

      • Many small accesses

  • File System

    • MakeDir, Copy, ScanDir, ReadAll, Make


Types of i o devices l.jpg
Types of I/O Devices

  • Behavior

    • Input, Output, Storage

  • Partner

    • Human/Machine

  • Data Rate

    • Human

      • Keyboard, 10b/sec

      • Voice, 100kb/sec

    • Hard Disk

      • 10Mb/sec


Hard disk l.jpg
Hard disk

1-10 inches

  • 2-20 Platters

  • 3600-7400 RPM

  • 1-10 Inch Diameter

  • 500-2000 tracks/surface

  • 32-128 sectors/track

  • Cylinder

    • All tracks at one position

2-20

Sectors

Track


Hard disk6 l.jpg
Hard Disk

  • Average Seek Time (average time to move a track)

    • 8-12 ms

    • Does not consider locality

  • Rotational Latency

    • 4-8 ms

    • Often dominates over Seek Time

    • Start reading to ring-buffer when track reached

  • Transfer Rate

    • 2-10 Mb/sec

30

31

32

1

2

3


Other properties l.jpg
Other Properties

  • Storage Size 500Mb-10Gb

  • Cylinder 0, Boot Block

  • Partition Information

    • Usually a Physical Disk is devided into Smaller Partitions

    • File System Information

  • File System

    • The “data structure” for storing files and folders

    • Usually Hierarchical

      • Folders, sub folders and files

      • File types, (program/data-format) and protection bits


Scsi eide i o bus l.jpg
SCSI/EIDE I/O Bus

  • SCSI

    • General purpose interface for HDs, Scanners, Streamers, etc

    • Both synchronous/asynchronous operation

    • 5Mb/sec (standard SCSI higher for wide and ultra-wide)

    • 7 Devices/Bus Mastering/Self Selection Arbitration

  • EIDE

    • HDs and HD like devices (CR-ROMs etc)

    • Synchronous

    • 5Mb/sec

    • 2 Devices on each controller

    • HD controller on Interface


Networks l.jpg
Networks

  • RS-232, copper wire 19.2kbit/sec

    • Serial Point to Point Protocol (ppp)

  • LAN (Local Area Network), coaxial 100Mbit/sec

    • Ethernet 10Mbit/sec

    • Package 128-1530 bytes

    • Actually a bus with collision detection

  • Long Haul Network, fiber 1Gbit/sec

    • ARPANET (US government) became INTERNET

    • Packet Switched Networks


Network file system l.jpg
Network File System

  • Mounting Devices over the Network (usually LAN)

  • Local and Network devices transparent to User

  • Network Server - Local Client (a protocol)

  • Needs support by the OS

    • Local TCP stack, handles streams of I/O

    • Network Server forwards these streams

    • “Samba Server” makes Unix devices available to PCs


Graphics adapters l.jpg
Graphics Adapters

  • Each pixel uses a bit array (1-24bits)

  • 1280*1024*24bits/pixel needs approximately 4Mb

Red

Green

Blue

Yellow

White

8 + 8 + 8 =24bits/pixel


Graphics adapter design l.jpg
Graphics Adapter Design

  • Needs to update the Screen 60-100 times/sec (frames)

  • At 80Hz*4Mb=320Mb/sec Huge Throughput

  • We use special VRAM (Video RAM)

    • Shifts out bits to DAC at this high rate

  • Usually contain a Graphics Accelerator, which

    • Move and Copy Blocks of data in local VRAM

    • Perform operations, like AND/EXOR (bit mask)

    • Functions Line, Polygon Fill

    • “3D” functions like:

      • Polygon Shading, Texture Mapping etc.


Video application example l.jpg
Video Application Example

  • A system for real-time video recording/playback

    • A Frame Grabber, records video to HD

    • A Graphics Adapter displays video from HD

  • 640*480*8bits/pixel (256 colors)

    • 300kb/frame recording or playback

  • We do NOT want CPU in data path


Approach 1 l.jpg
Approach 1

  • The Frame Grabber records one Frame (300kb) to local buffer

    • Frame Grabber gives interrupt

  • The OS sets up a DMA transfer from FG to RAM

    • The DMA gives interrupt

  • The OS sets up a DMA transfer to HD

    • The DMA gives interrupt

    • The HD gives interrupt, data written to disk

  • At 25 frames/sec (TV quality) this gives

    • 2 (first to RAM then to HD) * 300 * 25 = 15Mb/sec

Hmm, no Good! A lot bus activity, too high HD throughput

(and this is for just recording)


Approach 2 l.jpg
Approach 2

  • Put MPEG-2 hardware compression on the Frame Grabber, now only 30kb/frame

    • Frame Grabber gives interrupt

  • The OS sets up a DMA transfer from FG to HD

    • The DMA gives interrupt

    • The HD gives interrupt, data written to disk

  • At 25 frames/sec (still TV quality) this gives

    • 30 * 25 = 750kb/sec

  • Simultaneous record/playback gives

    • 1.5 Mb HD throughput, which is possible but still quite high

    • A lot of activity on the SCSI bus


Approach 3 l.jpg
Approach 3

  • Frame Grabber

    • MPEG-2 hardware compression, now only 30kb/frame

    • Graphics Adapter, that can display MPEG-2 frames

    • SCSI bus to local HD for video storage

    • Interrupt each frame recorded, or finished playback sequence

  • Best solution! Almost no bus PC bus activity

  • You get what you pay for, this one will cost you $$$$


High fidelity audio l.jpg
High Fidelity Audio

  • PCM 44.1 kHz 16bits Stereo (WAV/AIFF)

  • 96 db signal/noice ratio

16 bit

signed integer

Left

16 bit

signed integer

Right


Sound cards l.jpg
Sound Cards

  • Wave-Table playback

    • 16 bit (Stereo at 44.1 kHz)

    • 32 voices

    • 5.6 Mb/sec (quite high bandwidth)

WaveTable

ROM/RAM

Signal Processor

Audio

MIX

DA/Filter

...


Audio i o l.jpg
Audio I/O

  • In/Out

    • Data Buffers

    • DMA Channel

    • IRQ (Interrupt number) 2 IRQ for full duplex operation

  • 350kb/sec throughput on bus, OK

In Buffer

DSP

Filter/Ad

Audio In

Out Buffer

DA/Filter

Audio Out


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