Flash Storage and IO Operation Lecture Objectives: 1) 2) 3) 4) 5) Explain the limitations of flash memory. Define wear leveling. Define the term IO Transaction Define the terms synchronous bus and asynchronous interconnect.
Explain the difference between polling and interrupts Nonvolatile semiconductor storage 100 1000 faster than disk Smaller, lower power, more robust But more $/GB (between disk and DRAM) Chapter 6 Storage and Other I/O Topics 2 6.4 Flash Storage Flash Storage
Flash Memory Performance Limitations Cost is higher than mechanical drives Cells wear out over time CS2710 Computer Organization 3 Flash memory can only be written to a finite number of times Write operations begin to fail after 10000100000 cycles (current technology)
Disk drives or DRAM memory do not have this limitation Wear leveling A technique which organizes blocks of data so that blocks which have been rewritten many times are exchanged for blocks which have not been written as often. CS2710 Computer Organization 4 CS2710 Computer Organization
5 Definitions Processor memory bus A bus that connect the processor to the memory, and is generally high speed. Backplane bus A bus that is designed to allow processors, memory, and I/O devices to coexist on a single bus IO Transaction
A sequence of operations over the interconnect that includes a request, and may include a response either of which may carry data. Synchronous bus A bus that includes clock and control lines and a fixed protocol for communicating that is relative to the clock Asynchronous interconnect A mechanism which uses a handshaking protocol rather than a clock to accommodate devices of varying speeds. CS2710 Computer Organization 6
I/O is mediated by the OS Multiple programs share I/O resources Need protection and scheduling I/O causes asynchronous interrupts Same mechanism as exceptions I/O programming is fiddly OS provides abstractions to programs 6.6 Interfacing I/O Devices
I/O Management I/O Commands I/O devices are managed by I/O controller hardware Transfers data to/from device Synchronizes operations with software Command registers Cause device to do something Status registers Indicate what the device is doing and occurrence of errors
Data registers Write: transfer data to a device Read: transfer data from a device I/O Register Mapping Memory mapped I/O Registers are addressed in same space as memory Address decoder distinguishes between them OS uses address translation mechanism to make them only accessible to kernel I/O instructions Separate instructions to access I/O registers
Can only be executed in kernel mode Example: x86 Polling Interrupts -> Part #1 10 Polling Periodically check I/O status register If device ready, do operation If error, take action
Common in small or low-performance realtime embedded systems Predictable timing Low hardware cost In other systems, wastes CPU time Chapter 6 Storage and Other I/O Topics 11 Interrupts No! Shut up and Ill tell you when we are there!
Interrupts -> Part #1 12 Interrupts When a device is ready or error occurs Controller interrupts CPU Interrupt is like an exception But not synchronized to instruction execution Can invoke handler between instructions
Cause information often identifies the interrupting device Priority interrupts Devices needing more urgent attention get higher priority Can interrupt handler for a lower priority interrupt Chapter 6 Storage and Other I/O Topics 13
But for the marriage of Drusilla with Azizus, it was in no long time afterward dissolved upon the following occasion: While Felix was procurator of Judea, he saw this Drusilla, and fell in love with her; for she did indeed...
Abraham's Journey To The Promised Land Abraham and his wife Sarah, lived in a place called Ur. Abraham was a faithful man of God. One day God told Abraham to take all his family and belongings and leave Ur and...
"Purpose becomes a more powerful and enduring . source of energy . in our lives in three ways: when its source moves from negative to positive, external to internal, and self to others." Jim Loehr and Tony Schwartz, Authors "The...
A—All of the benefits should be accounted for as pensions. In accordance with Statements No. 68, Accounting and Financial Reporting for Pensions, No. 73, Accounting and Financial Reporting for Pensions and Related Assets That Are Not within the Scope of...
On service fellows (BCH San Francisco and Oakland) attend conference from 7-9 AM. Board Review and Bedside teaching (9-11AM) occurs for off service fellows . CICU specific. CICU specific. Weekend call:
Wegmans Frozen Cookie Capacity Increase Final Project Presentation. Richard Latham, Bridget Eggers, Tyler Brent, Valeria Gonzalez. A DAY IN THE PROCESS. ... Incorporate mixer schedule into the ROSS system. Separate changeover time and sanitation time.
Kevin Rolland Bronze medal in Free style ski. Jean-Frédéric Chapuis Gold medal, Arnaud BovolentaSilvermedal and Jonathan Midol Bronze medal in ... Ski cross. Some French olympic champions 2014. Here are some French olympic champions Jean-Guillaume Beatrix, Bronze medal in ....
Climate. The kind of social and emotional mood we create for others. "When we expect more favorable things of people, we create a more positive interpersonal climate for them."-- Dr. Robert Rosenthal. The Pygmalion Effect, CRMLearning, CA, www.crmlearning.com. Negative ....
Ready to download the document? Go ahead and hit continue!