> > > For xfs used this command: > > > xfs_io -c "stat" /mnt/testfile > > > And for ext4 used this: > > > filefrag /mnt/testfile > > > > filefrag merges contiguous extents, and only counts up for discontiguous > > mappings, while fsxattr.nextents counts all extent even if they are > > contiguous. So you probably want to use filefrag for both cases. > > Got it — thanks for the clarification. We'll switch to using filefrag > and will share updated extent count numbers accordingly. Using filefrag, we recorded extent counts on xfs and ext4 at three stages: a. Just after a 1G random write, b. After a 30-second wait, c. After unmounting and remounting the filesystem, xfs Base a. 6251 b. 2526 c. 2526 Parallel writeback a. 6183 b. 2326 c. 2326 ext4 Base a. 7080 b. 7080 c. 11 Parallel writeback a. 5961 b. 5961 c. 11 Used the same fio commandline as earlier: fio --filename=/mnt/testfile --name=test --bs=4k --iodepth=1024 --rw=randwrite --ioengine=io_uring --fallocate=none --numjobs=1 --size=1G --direct=0 --eta-interval=1 --eta-newline=1 --group_reporting filefrag command: filefrag /mnt/testfile
