Sage-Tips

Is IPC faster than shared memory?

The IPC shared semaphore facility provides process synchronization. Shared memory is the fastest form of interprocess communication.

Why are memory-mapped files supported by current operating systems?

A memory-mapped file contains the contents of a file in virtual memory. This mapping between a file and memory space enables an application, including multiple processes, to modify the file by reading and writing directly to the memory.

How does shared memory work in Linux?

Shared memory is a feature supported by UNIX System V, including Linux, SunOS and Solaris. One process must explicitly ask for an area, using a key, to be shared by other processes. This process will be called the server. All other processes, the clients, that know the shared area can access it.

What are the advantages of IPC?

Advantages of using CICS Inter Process Communication

• Credential of current process accessing shared memory is checked.
• Owner and creator of shared memory is also checked.
• Remote Procedure Call information is stored in secured shared memory.

Which IPC method is more efficient?

Fastest IPC mechanism in OS is Shared Memory. Shared memory is faster because the data is not copied from one address space to another, memory allocation is done only once, andsyncronisation is up to the processes sharing the memory.

What is memory mapped file in Linux?

More precisely, a memory mapped file is a mirror of a portion (or entire) file on virtual memory managed completely by the operating system. In other words, whenever a file is memory mapped, the operating system will immediately map file memory to a region on virtual memory. You can think of this as some RAM space.

What is mmap used for Linux?

The mmap() function is used for mapping between a process address space and either files or devices. When a file is mapped to a process address space, the file can be accessed like an array in the program.

Does mmap copy data?

Mmap is sometimes the most efficient way to access data; why? Fewer copies: both standard IO and read/write copy the data out of the operating system into a user buffer. mmap brings the data into memory and lets your application access that data directly.

Memory-Mapped Files. A memory-mapped file contains the contents of a file in virtual memory. This mapping between a file and memory space enables an application, including multiple processes, to modify the file by reading and writing directly to the memory.

What are the IPC mechanisms in Linux?

This is the first article in a series about interprocess communication (IPC) in Linux. The series uses code examples in C to clarify the following IPC mechanisms: This article reviews some core concepts before moving on to the first two of these mechanisms: shared files and shared memory.

What is the fastest way to implement a shared memory IPC?

Finally, you need some way of blocking thread execution on the server thread while it waits for data. One of the fastest is the WaitForSingleObject function call. My implementation uses this function and waits on the named events. Most shared memory IPCs are implemented similar to the following:

What are persistent memory-mapped files?

Persisted memory-mapped files. Persisted files are memory-mapped files that are associated with a source file on a disk. When the last process has finished working with the file, the data is saved to the source file on the disk. These memory-mapped files are suitable for working with extremely large source files.