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The "u" in "uring" has nothing to do with its size but rather with it being a "userspace ring". The ring buffers used by this particular API reside in userspace
by WJW 4y ago
The "u" in "uring" has nothing to do with its size but rather with it being a "userspace ring". The ring buffers used by this particular API reside in userspace rather than in kernel memory.
- axboe 4y agoThis is correct, the "u" is for userspace/usermapped. The memory is actually allocate by the kernel, but it's mapped into the applications address space.
- loeg 4y ago> The ring buffers used by this particular API reside in userspace rather than in kernel memory. More specifically, the physical pages backing these ring buffers are pinned and mapped into both address spaces. (The kernel needs to be able to read submissions (sqes) off of it and write completions (cqes) into it, and could not do that if it were only mapped in userspace, or could be paged out.)