On Thu, Jul 11, 2024 at 11:36:28PM +0000, Wengang Wang wrote: > > > > On Jul 9, 2024, at 1:21 PM, Darrick J. Wong <djwong@xxxxxxxxxx> wrote: > > > > On Tue, Jul 09, 2024 at 12:10:28PM -0700, Wengang Wang wrote: > >> According to current kernel implemenation, non-zero extsize might affect > >> the result of defragmentation. > >> Just print a warning on that if non-zero extsize is set on file. > > > > I'm not sure what's the point of warning vaguely about extent size > > hints? I'd have thought that would help reduce the number of extents; > > is that not the case? > > Not exactly. > > Same 1G file with about 54K extents, > > The one with 16K extsize, after defrag, it’s extents drops to 13K. > And the one with 0 extsize, after defrag, it’s extents dropped to 22. extsize should not affect file contiguity like this at all. Are you measuring fragmentation correctly? i.e. a contiguous region from an larger extsize allocation that results in a bmap/fiemap output of three extents in a unwritten/written/unwritten is not fragmentation. -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
