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4

And when a system call happens that kernel process gets loaded and a handler gets executed. This would be extremely slow as a process context switch would be required to make a kernel call and another one when the kernel call returns. Please consider that even a simple operation like printing "Hello World" to the screen using printf() in C ...


2

Asking about RAM is wrong, what counts is address space. If your OS is using virtual memory (which is most likely the case), then the mapping of address space to RAM is arbitrary and can change at any time, so address space counts. The address space assigned to a process is (almost) free and can be huge; how much of it is used is what actually costs. So in ...


4

If the process asks for 100MB, there has to be a contiguous 100MB free in the address space of the process (virtual memory), but those addresses can be mapped to non-contiguous pages of physical memory. The allocated addresses might not even be backed by physical pages until they are written to – Linux happily overcommits memory. On 64 bit systems it's ...


6

aren't processes already fairly isolated via separate virtual address spaces? A bit isolated, yes, in that one process cannot access the memory of another process. But it can do various other things which will interfere with the proper running of other processes, for example by using up all of one resource (CPU, memory, filesystem handles) or another. does ...


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