> Can you gather some performance numbers please - i.e. how long does it take > to map such file without FIEMAP_FLAG_COW and how long with it? I'm not > completely convinced it will make such a huge difference in practice (given > du(1) isn't very performance critical application). Seconded. I'd like to see measurements (wall time, cpu, ios) of the time it takes to find shared extents on a giant file *on a fresh uncached mount*. Because this interface doesn't help the file system do the work more efficiently, the kernel still has to walk everything to see if its shared. It just saves some syscalls and copying. That's noise compared to the io/cache footprint of the operation. - z -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
