Bug 248417 - top(1): ARC info is displayed on an UFS only system with a 2kb value
Summary: top(1): ARC info is displayed on an UFS only system with a 2kb value
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: bin (show other bugs)
Version: CURRENT
Hardware: Any Any
: --- Affects Some People
Assignee: freebsd-bugs (Nobody)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-08-01 17:59 UTC by Gordon Bergling
Modified: 2020-10-28 06:47 UTC (History)
2 users (show)

See Also:


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Description Gordon Bergling freebsd_committer 2020-08-01 17:59:29 UTC
After some time of stressing the system I see an ARC info displayed via top(1) with a value of "2048B Uncompressed". The system is UFS only, but has loaded the zfs.ko. An example output is the following,

--------------------------------------------------------------------------
last pid: 67230;  load averages:  1.43,  1.37,  1.51                                                                                  up 3+01:30:32  19:51:53
43 processes:  3 running, 40 sleeping
CPU: 46.7% user,  0.0% nice,  2.1% system,  0.1% interrupt, 51.1% idle
Mem: 221M Active, 16M Inact, 756K Laundry, 238M Wired, 97M Buf, 426M Free
ARC:
     2048B Uncompressed
Swap: 2048M Total, 86M Used, 1961M Free, 4% Inuse

  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
67230 root          1  92    0   211M   155M CPU3     3   0:11  98.50% c++ -target aarch64-unknown-freebsd13.0 --sysroot=/tank/nfs_public/tiny/obj/tank/nfs_p
66978 root          1  92    0   235M   167M CPU2     2   0:11  97.65% c++ -target aarch64-unknown-freebsd13.0 --sysroot=/tank/nfs_public/tiny/obj/tank/nfs_p

--------------------------------------------------------------------------

The system is a -CURRENT from the 29th of July on arm64 (RPi4b). The uname -a output is the following,

--------------------------------------------------------------------------
FreeBSD tiny.0xfce3.net 13.0-CURRENT FreeBSD 13.0-CURRENT #22 9439cdbfcc6-c270217(master): Wed Jul 29 17:45:44 CEST 2020     root@tiny.0xfce3.net:/tank/nfs_public/tiny/obj/tank/nfs_public/tiny/src/arm64.aarch64/sys/GENERIC-TCP  arm64
--------------------------------------------------------------------------
Comment 1 Gordon Bergling freebsd_committer 2020-10-27 11:14:41 UTC
After some investigation, this bug can be triggered if a kyua run was made and the system has only UFS partitions.
Comment 2 Andriy Gapon freebsd_committer 2020-10-27 14:47:04 UTC
So, what precisely do you consider to be a bug?
That the ARC line is present at all? Its appearance? Something else?

It's plausible that the tests that you run do test ZFS.
Comment 3 Gordon Bergling freebsd_committer 2020-10-27 15:08:53 UTC
(In reply to Andriy Gapon from comment #2)

The ARC line isn't present after boot until I run 'kyua test -k /usr/tests/Kyuafile' as root. It is likely that a ZFS test is causing the ARC line to appear.

I would think that no ARC line should be printed by 'top' if the state isn't valid, like '2048B Uncompressed' and everything else is zero.
Comment 4 Andriy Gapon freebsd_committer 2020-10-28 06:47:50 UTC
(In reply to Gordon Bergling from comment #3)
Maybe it's just an unusual state, but not invalid.
Not sure...