Exam 2

A minimal software processor in whose context a series of instructions can be executed.
Saving its context implies stopping the current execution and saving all the data needed to continue the execution at a later stage.

A software processor in whose context one or more threads may be executed.
Executing a thread, means executing a series of instructions in the context of that thread.

The minimal collection of values stored in the registers of a
processor used for the execution of a series of instructions (e.g., stack pointer,
addressing registers, program counter)

The minimal collection of values stored in registers and
memory, used for the execution of a series of instructions (i.e., processor
context, state)

The minimal collection of values stored in registers and
memory, used for the execution of a thread (i.e., thread context, but now also
at least MMU register values)

Do threads or processes share the same address space?

What is "cheaper" thread switching or process switching?

what is an example of 1 indirect cost for context switching

This describes what kind of thread?:
all operations can be handled within a single process
all services provided by the kernel are done on behalf of the process where the thread lives
threads are used when there are many external events
threads block on a per event basis

This describes what kind of thread?:
the kernel has an implementation of threads
if a thread is blocked the kernel can schedule the thread associated with the event
thread signaling is done by the kernel
each thread operation requires a trap to the kernel

What does this describe?:
kernel threads managing user threads

When user level threads block, __ also is blocked

What is TLP?

Why is ___ important?:
hardware changes faster than software
ease of portability and code migration
isolation of failing or attacked components

A VM with a seperate set of instructures, an interpereter/emulator, running atop an OS

A VM with low-level instructions, along with bare-bones minimal operating system.

A VM with low-level instructions, but delegating most work to a full-fledged OS

if and only if executed in
user mode, it causes a trap to the operating
system

An instruction that may affect configuration of a machine (e.g., one affecting
relocation register or interrupt table)

An instruction whose effect is partially determined by context (e.g., POPF sets an
interrupt-enabled flag, but only in system mode).

condition for virtualization

modify guest OS, either by preventing nonprivileged sensitive instructions, or
making them nonsensitive (i.e., changing the context)

a collection of processes in a container that is given their own view of identifiers

combine several file systems into a layered fashion with only the highest layer
allowing for write operations (and the one being part of a container)

resource restrictions can be imposed upon a collection of processes

In this window system, your computer acts as a client to the x-kernel, which then will process things for you and display the results to the screen

What are the issues with X windowing system?
no clear seperation between application logic vs __ commands

This is an alternative to X window system, it lets applications control the display completely. (its more efficient too)

Billions of websites, billions of different computers and screens, How do we make an ultimate networked user interface to websites?

Server handles the request before attending a next request

Uses a dispatcher, which picks up an incoming request that is then passed
on to a separate thread/process

ftp is port

telnet (file transfer) is port

smtp (mail) is port

www (web) port

how can we handle out-of-band communication? this is when we need to interrupt a server once it is busy with a lower priority task? We can use TCP or a __ for urgent messages

Stateless or stateful?:
- dont record whether a file has been opened
- dont promise to invalidate a clients cache
- dont keep track of your clients
- no status on cleint after handling request

they are specialized servers designed to manage and serve distributed objects which are instances of classes that encapsulate both data and behavior and can be invoked remotely.

policies concerning threading models for object servers ( whether they are activated in a single threaded context one request at a time, as a per thread request such that each request handled by a separate thread ,or in a thread pool context by a thread selected form a pool of threads.

what implements a specific activation policy?

This is the three tier architecture for server ___:
1. presentation tier (front end)
2. application layer (middleware, request handling)
3. data tier (backend) databases lol

___s like Akamai are used to distribute cache data closer to a geographic location

Why do we migrate code?
a) ensuring that servers in the data center are sufficiently loaded
b) minimizing communication needed between client and server
c) a and b

What if you have something computationally heavy, distributed across a long distance, but you CANT have clients send data because of privacy?

move only the code and data segment of a thread to another machine, then reboot execution

Move the entire component (thread) to another machine, including execution state.
can be achieved with migration (move object over)
or cloning (start clone and set in same execution state)

1.__ migrates vms by ___ memory pages to the new machine and resending the ones that are later modified during the migration process

2.___ and ___ implies stopping the current virtual machiene, copying over memory, and starting the new virtual machine.

3.Letting the new virtual machine ___ in new pages as needed: processes start on the new virtual machine immediately and copy memory pages on demand.

A complete migration may actually take tens of seconds. We also need to realize that during the
migration, a service will be completely unavailable for multiple seconds.

Layers of OSI model

OSI physical layer is for

osi data link layer is for

osi network layer is for

osi transport layer is ___ or UDP

TCP is ___ based

UDP is ___ based

The osi ____ layer is to provide common services and protocols that can
be used by many different applications

Middle ware contains
a) communication, naming, and security protocols
b) unmarshaling of data (turn into bits or change bits to normal data)
c) scaling mechanisms
d) both a and b
e) all

This type of messaging, discards messages when they can't be delivered

This type of messaging stores messages until they can be delivered

Client waits for reply

Client continues without waiting

At request submission
At request delivery
After request processing
these are all of the places for synchronization

• Client cannot do any other work while waiting for reply
• Failures have to be handled immediately: the client is waiting
• The model may simply not be appropriate (mail, news)

this form of middleware implements ___ ___ Communication
Messages are queued
Know that the middleware often ensures fault tolerance
Know its benefits:
Decouples sender and receiver
Enables scalability and resilience

parameters are passed in RPC by marshaling (converting data to byte stream), and with ___ agreements(int, float..)

while procedure is executed, nothing can be
assumed about parameter values.

BERKELEY SOCKET FUNC ____ Create a new communication end point

BERKELEY SOCKET FUNC ____ attach a local address to a socket

BERKELEY SOCKET FUNC ____ tell operating system what the maximum number of pending connection requests should be

BERKELEY SOCKET FUNC ____ block caller until a connection request arrives

send some data over the connection

recieve some data over the connection

release the connection