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Thread: 10.04: high load average at idle

  1. #1
    Join Date
    Jan 2008
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    Ubuntu 10.04 Lucid Lynx

    Exclamation 10.04: high load average at idle

    Since upgrading from 9.10 to 10.04, my system is noticeably less responsive and exhibits halting behavior for at times 10s of seconds. There is nothing obvious in the various logs that I can find. The only objective indication I can find that demonstrates that something is seriously wrong is that my load average never drops below 0.5 and is often over 1.5, even at idle. In this situation, top/ps/whatever shows very few processes running (usually just top). This suggests to me that either the new kernel scheduler is horrible or that something new is resulting in blocking I/O or other uninterruptable sleeps.

    Typical top output:
    top - 12:18:01 up 1 day, 49 min, 5 users, load average: 1.42, 0.86, 0.71
    Tasks: 262 total, 1 running, 261 sleeping, 0 stopped, 0 zombie
    Cpu(s): 0.9%us, 0.8%sy, 0.0%ni, 97.6%id, 0.0%wa, 0.0%hi, 0.7%si, 0.0%st
    Mem: 8194400k total, 6852456k used, 1341944k free, 729512k buffers
    Swap: 9936160k total, 0k used, 9936160k free, 3258392k cached

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    5957 mthome 20 0 1058m 293m 39m S 3 3.7 17:20.73 firefox-bin
    10 root 20 0 0 0 0 S 2 0.0 12:09.05 ksoftirqd/2
    7 root 20 0 0 0 0 S 1 0.0 11:01.10 ksoftirqd/1
    1343 root 20 0 166m 74m 22m S 1 0.9 37:20.27 Xorg
    2364 mthome 20 0 19348 1528 1052 R 1 0.0 0:00.25 top
    13 root 20 0 0 0 0 S 0 0.0 13:02.04 ksoftirqd/3
    74 root 20 0 0 0 0 S 0 0.0 2:36.92 kondemand/2
    2280 mthome 20 0 1021m 52m 25m S 0 0.7 1:09.97 pidgin
    2286 mthome 20 0 313m 67m 23m S 0 0.8 17:41.96 compiz
    2287 root 20 0 16896 740 508 S 0 0.0 0:12.93 dovecot
    Can anyone suggest anything to help me debug this?

    Thanks

  2. #2
    Join Date
    Apr 2006
    Location
    Claremont CA
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    292
    Distro
    Ubuntu Studio 10.04 Lucid Lynx

    Re: 10.04: high load average at idle

    I'd try looking at the load avg when an xsession isn't running. If it looks better then I'd try starting individual programs through a xterm session. Quick guess however is the Tracker daemon is indexing..



    Quote Originally Posted by mthome View Post
    Since upgrading from 9.10 to 10.04, my system is noticeably less responsive and exhibits halting behavior for at times 10s of seconds. There is nothing obvious in the various logs that I can find. The only objective indication I can find that demonstrates that something is seriously wrong is that my load average never drops below 0.5 and is often over 1.5, even at idle. In this situation, top/ps/whatever shows very few processes running (usually just top). This suggests to me that either the new kernel scheduler is horrible or that something new is resulting in blocking I/O or other uninterruptable sleeps.

    Typical top output:

    Can anyone suggest anything to help me debug this?

    Thanks
    cant' spell and 'man' challenged, thank goodness for tab-complete!

  3. #3
    Join Date
    Jan 2008
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    17
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    Ubuntu 10.04 Lucid Lynx

    Re: 10.04: high load average at idle

    No significant disk i/o in either case and I disabled tracker and similar ilk some time ago. There's some evidence that this is a kernel issue. I see surprisingly high ksoftirqd times - Nearly an hour of CPU time in 24 hours.

  4. #4
    Join Date
    Jan 2008
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    Ubuntu 10.04 Lucid Lynx

    Re: 10.04: high load average at idle

    Still not thrilled and it still feels less responsive than 9.10, but the RT kernel helps a lot. The ksoftirqds are back down where they belong and loadaverage runs around .20 at idle (+top).

  5. #5
    Join Date
    May 2010
    Beans
    7

    Re: 10.04: high load average at idle

    I have exactly the same problem, but it appears randomly it is not always like so. Anyone have any clues?

    Code:
    top - 12:14:06 up  3:24,  3 users,  load average: 1.17, 1.21, 1.03
    Tasks: 201 total,   1 running, 200 sleeping,   0 stopped,   0 zombie
    Cpu(s): 13.9%us, 11.8%sy,  0.2%ni, 73.3%id,  0.0%wa,  0.8%hi,  0.0%si,  0.0%st
    Mem:   4009668k total,  3907020k used,   102648k free,    41808k buffers
    Swap:  3534260k total,    19964k used,  3514296k free,  2814808k cached
    
      PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND            
     1144 root      20   0  191m  37m  17m S   18  1.0  19:22.10 Xorg               
     6086 lofas     20   0  873m  70m  20m S    9  1.8   0:29.10 chrome             
     1807 lofas      9 -11  272m 4708 3236 S    5  0.1   1:30.28 pulseaudio         
     1975 lofas     20   0  677m  77m  22m S    5  2.0   6:33.33 chrome             
     1798 lofas     20   0  358m  29m 5232 S    4  0.8   4:45.00 compiz             
     4421 lofas     20   0  219m  19m 8988 S    4  0.5   1:24.31 gnome-terminal     
     4028 lofas     20   0  238m  20m  11m S    3  0.5   9:00.42 npviewer.bin       
     2040 lofas     20   0  367m  17m 8100 S    1  0.4   2:19.66 empathy            
     6171 lofas     20   0 19216 1464 1052 R    1  0.0   0:03.00 top                
     4009 lofas     20   0 98284  14m 2232 S    1  0.4   0:36.92 desktopcouch-se    
     1797 lofas     20   0  521m  35m  16m S    0  0.9   0:26.70 nautilus

  6. #6
    Join Date
    May 2010
    Beans
    7

    Re: 10.04: high load average at idle

    Quote Originally Posted by mthome View Post
    Still not thrilled and it still feels less responsive than 9.10, but the RT kernel helps a lot. The ksoftirqds are back down where they belong and loadaverage runs around .20 at idle (+top).
    This is definitely a kernel issue. It seems it has something to do with the load balancing for multi-cores. Running powertop shows way to high wakeups due to
    [kernel scheduler] Load balancing tick

    Reverting back to the Karmic-kernel helped a lot, but still the wakeups due to load balancing is to high, but load average drop to under 0.1 at least.

  7. #7
    Join Date
    Jun 2010
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    France
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    Ubuntu

    Re: 10.04: high load average at idle

    I've got the same problem on my ubuntu-server (10.04), load average always between 1 and 2 with nothing working on it !

  8. #8
    Join Date
    Apr 2006
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    22
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    Ubuntu 6.10 Edgy

    Re: 10.04: high load average at idle

    I also have this issue. The load on my laptop stays high (around 1.5) and every once and a while will spike to > 10 and be completely unusable for several minutes. This only started happening when running 10.04. It happens very randomly, so I can't point to any one application causing this.

    I also have ubuntu 10.04 on my workstation and I don't see this behavior. However my workstation has two opteron cpus where as my laptop has a single dual core intel processor.

  9. #9
    Join Date
    Jun 2010
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    Ubuntu

    Re: 10.04: high load average at idle

    we must compare our kernels and version, I've got the bug on Ubuntu-server with 2.6.32-23-server 64bits

  10. #10
    Join Date
    Apr 2006
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    Ubuntu 6.10 Edgy

    Re: 10.04: high load average at idle

    Quote Originally Posted by ouafnico View Post
    we must compare our kernels and version, I've got the bug on Ubuntu-server with 2.6.32-23-server 64bits
    My laptop is running

    Code:
    Linux memwd2 2.6.32-23-generic #37-Ubuntu SMP Fri Jun 11 07:54:58 UTC 2010 i686 GNU/Linux

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