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Thread: Why all the cput is lost and where?

  1. #1

    Default Why all the cput is lost and where?

    Dear all, there are times after my opensuse 12.1 is running for some period, like 5-6 days without rebooting, that the performance goes really down. It reminds me the old days of windows 98 where one had to reboot system quite a lot to keep performance up.

    When this happes everything goes too slow (I have a four core cpu). Ksnapshot make 3-4 seconds to appear, writing text makes 2-3 seconds to appear in screen and so on....

    What I tried intuitively is to understand if there is something eating up my cpu.
    In the image below
    Imageshack - cpulost.jpg
    you will notice the problem

    On the middle bottom ksysguard reports cput at 75%, which can be an indicator why the system is slowing down. Also the graphs show the four cpus being quite busy.

    On the left side there is a ksysguard again showing the active processes ordered by cpu utilization, where you can see that the total sum of percentages does not get even close to the 75% .


    Then I thought that there might be some root processes (I am the only one using that machine) eating the cpu so I sudo top. On the right side you will find the top running with root permissions.
    Even there the cpu utilization reported does not get close to the 75%

    What I am missing here and why I can not find what is eating cpu and makes system unresponive?

    Could you please help me with that?

    Regards
    Alex

  2. #2
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    Default Re: Why all the cput is lost and where?

    On Wed 05 Dec 2012 01:56:01 PM CST, alaios wrote:


    Dear all, there are times after my opensuse 12.1 is running for some
    period, like 5-6 days without rebooting, that the performance goes
    really down. It reminds me the old days of windows 98 where one had to
    reboot system quite a lot to keep performance up.

    When this happes everything goes too slow (I have a four core cpu).
    Ksnapshot make 3-4 seconds to appear, writing text makes 2-3 seconds to
    appear in screen and so on....

    What I tried intuitively is to understand if there is something eating
    up my cpu.
    In the image below
    'Imageshack - cpulost.jpg' (http://imageshack.us/f/689/cpulost.jpg/)
    you will notice the problem

    On the middle bottom ksysguard reports cput at 75%, which can be an
    indicator why the system is slowing down. Also the graphs show the four
    cpus being quite busy.

    On the left side there is a ksysguard again showing the active
    processes ordered by cpu utilization, where you can see that the total
    sum of percentages does not get even close to the 75% .


    Then I thought that there might be some root processes (I am the only
    one using that machine) eating the cpu so I sudo top. On the right side
    you will find the top running with root permissions.
    Even there the cpu utilization reported does not get close to the 75%

    What I am missing here and why I can not find what is eating cpu and
    makes system unresponive?

    Could you please help me with that?

    Regards
    Alex


    Hi
    You have a lot of disk I/O in wait ~50% plus your using swap, with 8GB
    of ram I would not expect that.

    I would guess it's you rsync job causing the I/O wait, run the iostat
    command;
    Code:
    zypper install sysstat
    iostat 2
    Run it with and without the rsync running and see if that makes a
    difference.

    What device are you running rsync too (maybe a slow device)?


    --
    Cheers Malcolm °¿° (Linux Counter #276890)
    openSUSE 12.2 (x86_64) Kernel 3.4.11-2.16-desktop
    up 1 day 0:57, 3 users, load average: 0.21, 0.12, 0.07
    CPU Intel i5 CPU M520@2.40GHz | Intel Arrandale GPU


  3. #3
    dd NNTP User

    Default Re: Why all the cput is lost and where?

    On 12/05/2012 02:56 PM, alaios wrote:
    > What I am missing here and why I can not find what is eating cpu and
    > makes system unresponive?


    i can't tell from what you posted, because i can't see what was going on
    with (for example) rsync, Skype, your sound system and others maybe..

    that is, a machine can bog down for causes other than just all CPU power
    is in use....like: if something is going on that completely FILLS the
    I/O (in and out) pipe going between two locations (via rsync) then that
    pipe is clogged and nothing else can pass through _until_ there is a
    break in the flow (maybe from your internal hard drive to an external
    USB or even to some machine on the other side of earth--which would also
    fill the networking pipe)

    so, if the access to the on board hard drive is BLOCKED (by rsync) when
    you click (or keystroke) to do a Ksnapshot, then the system has to
    _stop_ (or slow down) the rsync in order to access the hard drive to
    execute the ksnapshot executable..

    or, if you are streaming music from some online source which fills or
    almost fills the in/out bound network pipe and at the same time your
    Skype is being used by the skype network to relay traffic (yes, it can
    do that) then you might get slow response if you click to (say) change
    youtube...

    bottom line is: there are more things than just CPU usage that can
    (will) cause slow desktop response...and, most machines just don't have
    enough in/out capability to do every thing (huge down/uploads, stream
    music, do a video chat on skype, etc etc etc) at once

    next time, turn something off and see if the system becomes more
    'responsive'..

    ymmv, OH and have a look at atop, iotop, htop..

    OH2! there is no need to run top as root..

    --
    dd http://tinyurl.com/DD-Caveat
    http://tinyurl.com/DD-Software

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