3 ms·
I don't think O_DIRECT makes any guarantees about zero-copy operation. It merely disallows kernel-level caching of that data. But the kernel may make a private
by wtallis 6y ago
I don't think O_DIRECT makes any guarantees about zero-copy operation. It merely disallows kernel-level caching of that data. But the kernel may make a private copy that isn't caching.
- layoutIfNeeded 6y agoWho said it was guaranteed to be zero-copy? The original article said that the data must be copied based on some bogus handwavy argument, and I’ve pointed out that the manpage of write(2) contradicts this when it says the following: >File I/O is done directly to/from user-space buffers.