Issue probably with `top` and Uncompressed ARC display

[Dmitriy M.]

Hi all,

Got issue with displaying Uncompressed ARC in `top` (K Uncompressed and
negative Ratio) :

ARC: 360G Total, 55G MFU, 271G MRU, 245M Anon, 7976M Header, 27G Other
     281G Compressed, K Uncompressed, -5.70:1 Ratio

Sysctl counters:
[box:~]$ sysctl -a | grep compress
vfs.zfs.sync_pass_dont_compress: 5
vfs.zfs.compressed_arc_enabled: 1
kstat.zfs.misc.arcstats.uncompressed_size: 2679818006016
kstat.zfs.misc.arcstats.compressed_size: 301540177408

Running pretty old 11.2-BETA3 FreeBSD 11.2-BETA3 #0 r334277
512GiB RAM total
vfs.zfs.arc_max="360G"
vfs.zfs.arc_min="360G"

Is it (already known) bug in `top` or something wrong with system/ARC to
worry about?
I do not really believe that our data may be 8x compressed (on filesystem
via `zfs get compressratio` got 2.10x), but nothing suspicious with system
behaviour (CPU/IO/ZFS) was not noticed.

Thanks!