История изменений

Всё ожиданно.

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar xf /test/btrfs/firefox-127.0b5.source.tar.xz -C  /test/btrfs/
tar xf /test/btrfs/firefox-127.0b5.source.tar.xz -C /test/btrfs/  25,39s user 9,37s system 118% cpu 29,237 total

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar cf /test/btrfs/firefox.tar /test/btrfs/firefox-127.0
tar cf /test/btrfs/firefox.tar /test/btrfs/firefox-127.0  0,88s user 7,85s system 62% cpu 13,907 total

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar xf /test/ext4/firefox-127.0b5.source.tar.xz -C /test/ext4/
tar xf /test/ext4/firefox-127.0b5.source.tar.xz -C /test/ext4/  24,78s user 7,47s system 120% cpu 26,845 total

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar cf /test/ext4/firefox.tar /test/ext4/firefox-127.0
tar cf /test/ext4/firefox.tar /test/ext4/firefox-127.0  2,69s user 19,83s system 36% cpu 1:01,61 total

Снова неожиданно! Интересно, почему с дропом чистых страниц ext4 стало лучше?

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar xf /test/btrfs/firefox-127.0b5.source.tar.xz -C  /test/btrfs/
tar xf /test/btrfs/firefox-127.0b5.source.tar.xz -C /test/btrfs/  25,39s user 9,37s system 118% cpu 29,237 total

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar cf /test/btrfs/firefox.tar /test/btrfs/firefox-127.0
tar cf /test/btrfs/firefox.tar /test/btrfs/firefox-127.0  0,88s user 7,85s system 62% cpu 13,907 total

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar xf /test/ext4/firefox-127.0b5.source.tar.xz -C /test/ext4/
tar xf /test/ext4/firefox-127.0b5.source.tar.xz -C /test/ext4/  24,78s user 7,47s system 120% cpu 26,845 total

$ sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

$ time tar xf /test/ext4/firefox-127.0b5.source.tar.xz -C /test/ext4/
tar xf /test/ext4/firefox-127.0b5.source.tar.xz -C /test/ext4/  25,25s user 11,73s system 117% cpu 31,451 total