3 ms·
About the sync: you can bypass the fs cache by specifying iflag=direct/oflag=direct.
About the sync: you can bypass the fs cache by specifying iflag=direct/oflag=direct.
In fact, I'm quite surprised that it worked at all without direct. Even if sync writes the cached data to disk, it isn't exactly guaranteed that the following read will read them back instead of just returning a copy from the cache.
Nice, thanks for the tip!