1 what is concurrency? Flashcards
Concurrency
Sharing of resources in the same time frame. E.g. CPU, memory, I/O-device.
Communication
Convey information from one entity to another
Interrupt
Hardware notification of event. Detection part of instruction cycle. Source may be external, internal timer, division by zero…
Signal
Software notification of event. May be caused by interrupt handling.
Signal is generated
when the event that causes the signal occurs
Signal is caught
if the process that receives it, executes a handler for it.
A signal that is generated by the process or thread that receives it
is generated synchronously
Is a signal handler running concurrently?
Yes, at the very least concurrent with the main program.
A call directly into the kernel
is a system call
The programs that run in privileged mode
is the kernel
With full access to system resources, a program runs in
privileged mode.
reentrant function
Program function that is also a mathematical function
Program function that is also a mathematical function
is a reentrant function
A function that modifies local, static or global data
is a non-reentrant function
A is a non-reentrant function
modifies local, static or global data