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Add getcpu system call support for getting a NUMA node of the current thread#1575

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Eugene-Usachev wants to merge 4 commits intobytecodealliance:mainfrom
Eugene-Usachev:getcpu
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Add getcpu system call support for getting a NUMA node of the current thread#1575
Eugene-Usachev wants to merge 4 commits intobytecodealliance:mainfrom
Eugene-Usachev:getcpu

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@Eugene-Usachev
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Not much time ago I needed to get a NUMA node of the current thread. Linux provides the getcpu system call for it. But I did not find any Rust library that provides this function. I read this repository code, and I like what you are doing, so I want to help you to extend the functionality of this library.

I implemented the getcpu syscall for Linux only. Also, I develop with WSL, which adds \r\n at the end of lines, so I patched tests for not reading the end of lines.

Comment thread src/buffer.rs
Comment thread src/thread/sched.rs
/// [Linux]: https://man7.org/linux/man-pages/man2/getcpu.2.html
#[cfg(linux_kernel)]
#[inline]
pub fn getcpu() -> (usize, usize) {
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According to the Linux docs, the values written by getcpu have type unsigned int.

   int getcpu(unsigned int *_Nullable cpu, unsigned int *_Nullable node);

Would it be better to reflect them here as u32, rather than usize?

I see that sched_getcpu already returns usize, but that appears to be an error.

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I tried to do the same as sched_getcpu. To be honest, I am not sure what users prefer more here. I use numa_node: usize in my code, but I can't say everyone does it. If you want me to change it I can do it but I think it is not important.

Comment thread src/backend/linux_raw/vdso_wrappers.rs Outdated
@Eugene-Usachev
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Hi @sunfishcode, thanks for the previous feedback.

I have addressed most of the points (and resolved those conversations), but I had a question regarding some of them which I left open in the code comments.

Could you please take another look when you have a moment?

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