kworker/u4:1+tau stuck on G4 Sawtooth
Good Morning!
I recently acquired a pair of G4 Sawtooth towers that are basically
identical except for CPU and RAM - one is 450Mhz/384M and the other is
500Mhz/1G. When I initially setup the pair they were running the
6.12.6-1 kernel from the previous NETINST iso and everything ran fine
but I noticed that the CPU load reported under top, etc. remained at
1.00 across the board after the systems settled down from the initial
boot. I ran into the same problem with my initial installs of Sid on
Sparc64 last year and the problem persisted until the kernel was
upgraded to 6.7.7-1, so I thought maybe I just needed to wait for a
kernel update or two on powerpc for the issue, whatever it was, to get
flushed out. Well, I've been updating both machines frequently and they
are both now running 6.12.21-1 and the quirk is still there so I decided
to do a little looking. If you do a quick ps aux on the systems they
both show kworker/u4:1+tau in state D, so I did a quick iostat -p on
both systems which show that on the system disk there are ~1.73tps and
~33kB/s read and 4.6kB/s written with nothing running on the system
other than my login. In /proc the status for that PID shows:
Name: kworker/u4:1+tau
Umask: 0000
State: D (disk sleep)
Tgid: 19
Ngid: 0
Pid: 19
PPid: 2
...
and iotop shows virtually nothing hitting the disk, not even the swapfile.
Now, it has been more than a hot minute since I did anything with the
kernel other than do a recompile here and there, so I may be way off
target here. I am just trying to figure out why the load sticks at 1.00
and this kworker seems to hang on these 2 G4s but I am seeing nothing
similar on ARM, x86, x86_64 or Sparc64 with similar kernel releases.
Cheers,
Bill
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