Difference between shared memory and pipe in unix?
Taken from this article
(unnamed) Pipes
- Can switch between blocking andnon-blocking mode
- Don't have to free them when done
- Are automatically inherited bychildren
- Must read and write in a linearfashion
Shared Memory
- Can store structures
- Won't ever block - positive
- Can have as many programs read orwrite to it as you need
- Won't ever block - negative: must usesemaphores or your own spin-locks
- It's possible for it to not be freedeven when all programs exit
Shared Memory Vs Pipe-
Kernel-
Once Shared Memory is setup by the kernel there is no further need of kernel for the communication b/w process whereas in Pipe, data is buffered in the kernel space and requires system call for each access. Here, Shared Memory is faster than Pipe. It is a major drawback of the pipe becuase IPC is important for the computational speed up.
Communication
Shared Memory- Bidirectional whereas Pipe(unnamed Pipe)- Unidirectional.
Reliable
Shared Memory- Less Reliable(data mix up) whereas Pipe is more Reliable as data is buffered and is under control of the kernel.
Hope you like it.