Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
32 Cards in this Set
- Front
- Back
|
Name the 2 types of IPC. |
1. message passing 2. shared memory |
|
|
When is process messaging needed? |
when processes want to exchange data by sending and recieving messages. |
|
|
what two elements does a message exchange require? |
1) send 2) receive |
|
|
Is message exchange generalized? If so, how is generalization expressed? |
Yes. Senders and receivers can be on different machines. |
|
|
How is message exchange secure? |
the receiver can inspect an incoming message before processing it. |
|
|
When is a deadlock is said to occur?
|
two or more processes are blocked, and each of them is waiting for a resource that is held by another blocked process.
|
|
|
Make an analogy with which you could describe a deadlock to a layman.
|
ex: trying to negotiate a peace treaty between palestine and israel. MAKE YOUR OWNNNNNNNNNN!!!!!!!
|
|
|
What are the two elements of a deadlock?
|
1) processes, 2) resources
|
|
|
Define the relationship between any process P and resource R in a deadlock.
|
1) process P depends upon/holds on/owns resource R (arrow in), 2) process P needs/wants resource R (arrow out)
|
|
|
Can a serially resuable resource be used forever?
|
No, they exist in a limited quantity.
|
|
|
What are examples of serially reusable resources given a computer?
|
memory space, buffer space, disk space, USB slot (flash drives)
|
|
|
Can consumable resources be reused?
|
No.
|
|
|
What is an example of a consumable resource?
|
ex. messages: "owned by process that creates them until it releases them, and wanted by the process that will receive them
|
|
|
What are the four ways that a deadlock can be handled?
|
1) do nothing. 2) deadlock prevention (build systems that prevent deadlock), 3) deadlock avoidance (system states that avoid potential deadlocks), 4) deadlock detection (break deadlocks!!!)
|
|
|
What is the name of the necessary conditions that must be in effect for a deadlock to occur? How many are there?
|
Habermand's conditions, 4
|
|
|
What are Haberman's 4 conditions that are necessary for a deadlock to happen?
|
1) mutual exclusion, 2) hold and wait, 3) no preemtion, 4) circular wait
|
|
|
Define musual exlusion.
|
at least one of the processes involved in the deadlock must claim exclusive control of some of the resources ti requires
|
|
|
Define hold and wait.
|
processes can hold the resources that have already been allocated to them while waiting for additional resources
|
|
|
T/F no preemption means that a resource can be taken from a process at any given time.
|
F, see "define no preemption"
|
|
|
Define no preemption.
|
once a resource has been allocated to a process, it cannot be taken away or borrowed from that process until the process is finished.
|
|
|
Define circular wait.
|
there must be a circular chain of processes such that each process in the chain holds some resources that are needed by the next process in the chain (a vicious circle)
|
|
|
What must a system do to be using deadlock prevention?
|
it prevents any of the four necessary condition for deadlocks
|
|
|
Which of Haberman's conditions is denied in a deadlock prevition scheme?
|
whichever is easiest for the system!
|
|
|
What are the two drawbacks of denying mutual excluision?
|
1) many resources can only be used by one process at a time, 2) a message canot be held and sent at the same time
|
|
|
What are the two drawbacks of denying mutual excluision?
|
1) Processes are forced to acquire all their resources ahead of time, 2) this denial cannot be applied to consumable resources
|
|
|
What are the two drawbacks of allowing preemption?
|
1) work will be lost when a process steals storage space from another, 2) a process cannot be forced to send messages
|
|
|
What is the drawback of denying circular wait?
|
messages are forced to move in only one direction, i.e. processes cannot exchange messages
|
|
|
What resources work well with denial of circular wait?
|
ex. CPU and memory
|
|
|
What does denying ciruclar wait entail?
|
imposition of total order on all resource types and forcing all processes to follow said order in aquisition of new resources, all or one
|
|
|
What does allowing preemtion entail?
|
allowing processes to take away or borrow the resources that they need from the process that holds on them
|
|
|
What does denying hold and wait entail?
|
erquireing processes to get all resources they will need or none of them
|
|
|
What does denying mutual exclusion entail?
|
prevention of any one processes from claiming exclusive control of any resource(s)
|
