Hi all, I'm creating some applications using OFD lock to do IPC. However I do want to know what the kernel does behind my operations.

For example, when I acquired an OFD lock, what does the kernel do? Is the locking done in user space / kernel space / via I/O file system? Where's the lock structure resides in, is it in open file description table?

You might want to start here: https://www.gnu.org/software/libc/ma...ion-Locks.html

My initial reaction to these sort of things is always:
- why do you care ?.
- why haven't you checked the (kernel) source tree ?.

I care because I care performance... OFD suits my application well. I've done experiments to show it's good. However, I just wanted to know what's happening in the background to get clear about what my application is doing.

Really appreciated if there is any idea / advice to the question.

Did you read the link I posted?

If you’re ready to “care [about] performance” at this level, then you’re ready to look at the kernel source yourself instead of asking us to do it for you.

Sure. I wrote my whole program by referring to that but I need more detail behind program itself. I guess I'll need to look into kernel codes.

In my humble opinion, such concerns are both technically irrelevant and unnecessary. Linux is "the environment." If you have established to your satisfaction that "performance is 'good' when this strategy is used," then you are done. You should simply treat the kernel as "a black box." As long as it works and "performance is good [enough]," then you don't have to be concerned with "how it was implemented (in any particular case)."

"How does the kernel actually work? Well, there are these magical little elves who live in a tree ... and one of them is named Linus ..."

Do you have a problem somewhere? Do you want to solve something? Or do you want to inspect the source code of kernel (to understand OFD)? What is your goal?