Kernel Space: Once Upon atime

“Among the metadata maintained by most filesystems is the last
file access time, or ‘atime.’ This time can be a useful value to
have–it lets an administrator (or a program) know when a file was
last used. There is a strong downside to this feature, though: it
forces a write to the disk every time a file is accessed. So
read-only operations, which might have been satisfied entirely from
cache, turn into filesystem writes to keep the atime value up to
date. Related links

“A recent discussion on write throttling turned to atime after
Ingo Molnar pointed out that atime was probably a bigger
performance problem than just about everything else…”

Complete
Story