Constant load of 1 on a recent 12-STABLE

[Gordon Bergling]

Hi Allan,

On Wed, Jun 03, 2020 at 03:13:47PM -0400, Allan Jude wrote:
> On 2020-06-03 06:16, Gordon Bergling via freebsd-hackers wrote:
> > since a while I am seeing a constant load of 1.00 on 12-STABLE,
> > but all CPUs are shown as 100% idle in top.
> > 
> > Has anyone an idea what could caused this?
> > 
> > The load seems to be somewhat real, since the buildtimes on this
> > machine for -CURRENT increased from about 2 hours to 3 hours.
> > 
> > This a virtualized system running on Hyper-V, if that matters.
> > 
> > Any hints are more then appreciated.
> > 
> > Kind regards,
> > 
> > Gordon
> 
> Try running 'top -SP' and see if that shows a specific CPU being busy,
> or a specific process using CPU time

Below is the output of 'top -SP'. The only relevant process / thread that is
relatively constant consumes CPU time seams to be 'zfskern'.

-----------------------------------------------------------------------------
last pid: 68549;  load averages:  1.10,  1.19,  1.16 up 0+14:59:45  22:17:24
67 processes:  2 running, 64 sleeping, 1 waiting
CPU 0:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
CPU 1:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
CPU 2:  0.0% user,  0.0% nice,  0.4% system,  0.0% interrupt, 99.6% idle
CPU 3:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
Mem: 108M Active, 4160M Inact, 33M Laundry, 3196M Wired, 444M Free
ARC: 1858M Total, 855M MFU, 138M MRU, 96K Anon, 24M Header, 840M Other
     461M Compressed, 1039M Uncompressed, 2.25:1 Ratio
Swap: 2048M Total, 2048M Free

  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
   11 root          4 155 ki31     0B    64K RUN      0  47.3H 386.10% idle
    8 root         65  -8    -     0B  1040K t->zth   0 115:39  12.61% zfskern
-------------------------------------------------------------------------------

The only key performance indicator that is relatively high IMHO, for a 
non-busy system, are the context switches, that vmstat has reported.

-------------------------------------------------------------------------------
procs  memory       page                    disks     faults         cpu
r b w  avm   fre   flt  re  pi  po    fr   sr da0 da1   in    sy    cs us sy id
0 0 0 514G  444M  7877   2   7   0  9595  171   0   0    0  4347 43322 17  2 81
0 0 0 514G  444M     1   0   0   0     0   44   0   0    0   121 40876  0  0 100
0 0 0 514G  444M     0   0   0   0     0   40   0   0    0   133 42520  0  0 100
0 0 0 514G  444M     0   0   0   0     0   40   0   0    0   120 43830  0  0 100
0 0 0 514G  444M     0   0   0   0     0   40   0   0    0   132 42917  0  0 100
--------------------------------------------------------------------------------

Any other ideas what could generate that load?

Best regards,

Gordon