How to use shared memory with Linux in C

There are two approaches: shmget and mmap. I’ll talk about mmap, since it’s more modern and flexible, but you can take a look at man shmget (or this tutorial) if you’d rather use the old-style tools. The mmap() function can be used to allocate memory buffers with highly customizable parameters to control access and permissions, and to back them with file-system storage if … Read more

Oracle startup not possible – ORA-00845: MEMORY_TARGET not supported on this system – but memory size seems to be fine

You might be using Automatic Memory Management (AMM). AMM uses two initialization parameters: MEMORY_TARGET MEMORY_MAX_TARGET The shared memory file system should have enough space to accommodate the MEMORY_TARGET and MEMORY_MAX_TARGET values. To verify: In UNIX/Linux, you will have to set the shared memory file system accordingly. Verify: Set: For example,

What’s the difference between the message passing and shared memory concurrency models?

It’s a pretty simple difference. In a shared memory model, multiple workers all operate on the same data. This opens up a lot of the concurrency issues that are common in parallel programming. Message passing systems make workers communicate through a messaging system. Messages keep everyone seperated, so that workers cannot modify each other’s data. … Read more