[Bug 1586417] Re: Ubuntu 16.04 Desktop kworker/1:0 and systemd-timesync use 100% CPU, system very slow

[Martin Pitt]

Pleeeeeeeease file bugs with "ubuntu-bug", not directly on Launchpad, to
collect some actually useful information automatically.

Please run

   sudo journalctl -b > /tmp/journal.txt
   dmesg > /tmp/dmesg.txt

and attach both files here. Thanks!

** Changed in: systemd (Ubuntu)
       Status: New => Incomplete

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Title:
  Ubuntu 16.04 Desktop kworker/1:0 and systemd-timesync use 100% CPU,
  system very slow

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  Fairly new Ubuntu 16.04 Desktop installation with SSD hard drive, 64Gb memory. System runs OK for a day or two then desktop environment becomes completely unresponsive (display frozen).
  You can ssh into it (very slow response when you enter the password) and "top" shows that the CPU is being 100% used by three processes:

  top - 22:02:58 up  2:26,  4 users,  load average: 18.00, 17.96, 15.87
  Tasks: 293 total,  16 running, 274 sleeping,   0 stopped,   3 zombie
  %Cpu(s):  0.9 us,  9.6 sy,  0.0 ni, 89.1 id,  0.4 wa,  0.0 hi,  0.0 si,  0.0 st
  KiB Mem : 64276428 total, 60695284 free,  2272164 used,  1308980 buff/cache
  KiB Swap: 31412220 total, 31412220 free,        0 used. 61740156 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                  
   1278 systemd+  20   0   96092   2360   2188 R 106.7  0.0  51:11.22 systemd-timesyn          
     14 root      20   0       0      0      0 R 100.0  0.0  25:42.02 kworker/1:0              
   6314 colord    20   0  280824   6060   5428 R 100.0  0.0  25:42.01 colord-sane              
   2692 jrc       20   0 2869988 322548 271288 S   6.7  0.5   4:20.13 VirtualBox               
      1 root      20   0  120208   6332   3936 D   0.0  0.0   0:01.77 systemd                  
      2 root      20   0       0      0      0 S   0.0  0.0   0:00.01 kthreadd                 
      3 root      20   0       0      0      0 S   0.0  0.0   0:00.01 ksoftirqd/0              
      5 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 kworker/0:0H             
      7 root      20   0       0      0      0 S   0.0  0.0   0:07.34 rcu_sched                
      8 root      20   0       0      0      0 S   0.0  0.0   0:00.00 rcu_bh                   
      9 root      rt   0       0      0      0 S   0.0  0.0   0:00.00 migration/0              
     10 root      rt   0       0      0      0 S   0.0  0.0   0:00.02 watchdog/0               
     11 root      rt   0       0      0      0 R   0.0  0.0   0:00.02 watchdog/1               
     12 root      rt   0       0      0      0 S   0.0  0.0   0:00.00 migration/1              
     13 root      20   0       0      0      0 S   0.0  0.0   0:00.00 ksoftirqd/1              
     15 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 kworker/1:0H             
     16 root      rt   0       0      0      0 R   0.0  0.0   0:00.02 watchdog/2               
     17 root      rt   0       0      0      0 R   0.0  0.0   0:00.00 migration/2              
     18 root      20   0       0      0      0 S   0.0  0.0   0:00.04 ksoftirqd/2  

  Memory is clearly not an issue, but something seems to be making it
  hog CPU cycles and hang

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