[$] Why glibc's fstat() is slow

The fstat()
system call retrieves some of the metadata — owner, size, protections,
timestamps, and so on — associated with an open file descriptor. One might
not think of it as a performance-critical system call, but there are
workloads that make a lot of fstat() calls; it is not something
that should be slowed unnecessarily. As it turns out, though, the GNU C
Library (glibc) has been doing exactly that, but a fix is in the works.