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    SubjectRe: ksoftirqd high cpu load on kernels 2.6.24 to 2.6.27-rc1-mm1
    Hello
    I found the culprit.

    When using powertop I get:
    Top causes for wakeups:
    35,2% (251,0) ip : br_stp_enable_bridge (br_hello_timer_expired

    So I tried to turn them off with:
    brctl sethello br0 0
    but the problem persisted.
    If I do
    brctl sethello br0 5
    context switch rate drops 200 times and problem is gone.
    I think that the command brctl sethello br0 0 doesn't turn off hello
    messages, but sends them 250 times per second.

    Thanks for your time
    Dushan
    On Sat, Aug 30, 2008 at 3:48 AM, Dushan Tcholich <dusanc@gmail.com> wrote:
    > Hello again
    >
    >
    > On Mon, Aug 11, 2008 at 9:53 AM, Dushan Tcholich <dusanc@gmail.com> wrote:
    >> Hi
    >>
    >> On Sun, Aug 10, 2008 at 9:00 PM, Dushan Tcholich <dusanc@gmail.com> wrote:
    >>> Hi
    >>> Sorry for answering this late, but I was short on time and couldn't
    >>> get reiser4 to work with 2.6.27-rc2
    >>>
    >>> On Thu, Aug 7, 2008 at 8:58 PM, Francois Romieu <romieu@fr.zoreil.com> wrote:
    >>>> Dushan Tcholich <dusanc@gmail.com> :
    >>>> [...]
    >>>>> I googled a little and found out that oprofile is a little above my head.
    >>>>> So as I thought that some driver or HW might be responsible for this I
    >>>>> tried to disable various onboard HW and found out that if I disable
    >>>>> onboard ethernet problem dissapears, so now I've added netdev and
    >>>>> maintainer of R8169 driver to cc.
    >>>>
    >>>> Can you try 2.6.27-rc2 and send the content of /proc/interrupts, dmesg,
    >>>> ifconfig as well as a capture of the strange output from top ?
    >>>>
    >>
    >> I tried some more kernels and I had the same problem with 2.6.23.17
    >> and 2.6.27-rc1-mm1, but I couldn't reproduce it with kernel from
    >> sysresccd 1.0.1 http://www.sysresccd.org/ which is a patched version
    >> of 2.6.24 i think .7 when I booted it to change fs.
    >> Could it be that something in userspace is creating this?
    >>
    >
    > I dug a little more and found out some new info.
    > Unsolved bugreport with same symptoms:
    > http://marc.info/?l=linux-kernel&m=119613299024398&w=2
    > Problems appear if I start br0 interface, as context switch rate
    > increases 200 times. If I start eth0 instead everything looks ok.
    > The bugreport above had bridging enabled too.
    >
    > When using eth0 I get:
    > vmstat -n 1 10
    > procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
    > r b swpd free buff cache si so bi bo in cs us sy id wa
    > 2 0 17720 162288 25024 576852 0 0 21 22 6 9 10 4 85 0
    > 0 0 17720 162196 25024 576880 0 0 0 0 13 473 0 0 99 0
    > 0 0 17720 162196 25028 576880 0 0 0 4 36 1122 1 0 99 0
    > 0 0 17720 162196 25028 576880 0 0 0 0 83 844 0 0 99 0
    > 0 0 17720 162196 25028 576880 0 0 0 0 55 691 1 0 99 0
    > 0 0 17720 162556 25028 576880 0 0 0 0 13 490 1 0 100 0
    > 0 0 17720 162100 25028 576880 0 0 0 0 39 561 6 0 94 0
    > 1 0 17720 162028 25028 576880 0 0 0 0 16 1030 4 0 96 0
    > 0 0 17720 162028 25028 576880 0 0 0 0 40 597 1 0 99 0
    > 0 0 17720 162028 25028 576880 0 0 0 0 12 512 2 0 97 0
    >
    > top
    >
    > top - 03:30:07 up 6 days, 5:40, 4 users, load average: 0.02, 0.11, 0.28
    > Tasks: 149 total, 2 running, 147 sleeping, 0 stopped, 0 zombie
    > Cpu(s): 12.1%us, 3.3%sy, 0.0%ni, 84.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
    > Mem: 1033388k total, 871336k used, 162052k free, 25016k buffers
    > Swap: 610460k total, 17720k used, 592740k free, 576852k cached
    >
    > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    >
    > 4 root 15 -5 0 0 0 S 0 0.0 554:23.44 ksoftirqd/0
    >
    > If I use br0 I get:
    > vmstat -n 1 10
    > procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
    > r b swpd free buff cache si so bi bo in cs us sy id wa
    > 0 0 17720 162112 25048 577120 0 0 21 22 6 11 10 4 86 0
    > 0 0 17720 162152 25048 577120 0 0 0 0 14 111082 0 3 97 0
    > 0 0 17720 162152 25048 577120 0 0 0 0 23 107134 1 3 96 0
    > 1 0 17720 160148 25048 577120 0 0 0 0 11 109888 2 3 95 0
    > 0 0 17720 162032 25048 577120 0 0 0 0 33 108163 1 2 97 0
    > 0 0 17720 162032 25048 577120 0 0 0 0 7 104642 2 2 95 0
    > 0 0 17720 162020 25048 577120 0 0 0 0 41 109135 0 2 98 0
    > 0 0 17720 162036 25048 577120 0 0 0 0 9 105133 0 3 96 0
    > 0 0 17720 162020 25048 577120 0 0 0 0 42 107605 1 2 97 0
    > 1 0 17720 162032 25048 577120 0 0 0 0 5 110768 0 2 98 0
    >
    > top
    >
    > top - 03:32:03 up 6 days, 5:41, 4 users, load average: 0.09, 0.10, 0.26
    > Tasks: 148 total, 2 running, 146 sleeping, 0 stopped, 0 zombie
    > Cpu(s): 4.8%us, 2.0%sy, 0.0%ni, 93.0%id, 0.0%wa, 0.0%hi, 0.2%si, 0.0%st
    > Mem: 1033388k total, 871564k used, 161824k free, 25048k buffers
    > Swap: 610460k total, 17720k used, 592740k free, 577120k cached
    >
    > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    > 11489 dusan 20 0 235m 85m 24m R 6 8.5 1:03.51 firefox
    > 4 root 15 -5 0 0 0 S 7 0.0 554:24.04 ksoftirqd/0
    >
    > I start br0 like this in /etc/conf.d/net
    >
    > bridge_br0="eth0"
    > config_eth0=( "null" )
    > config_br0=( "192.168.1.3/24" )
    > RC_NEED_br0="net.eth0"
    > brctl_br0=( "setfd 0" "sethello 0" "stp off" )
    > #routes_br0=( "default gw 192.168.1.3" )
    > depend_br0() {
    > need net.eth0
    > }
    >
    > I start eth0 like this in /etc/conf.d/net
    > config_eth0=( "192.168.1.3/24" )
    >
    >>> I've copied my root to ext3 partition and with vanilla 2.6.27-rc2 I got:
    >>> -With my .config problem is still here
    >>> -With only rtl8169 removed from config there is no problem
    >>>
    >>>> It seems rather benign though.
    >>>>
    >>> Well I wouldn't agree from power managment standpoint :). This nic is
    >>> in a lot of laptops.
    >>> 8% of 2.13GHz Core2Duo CPU is a lot :)
    >>>
    >>> Btw. should LKML be removed from cc?
    >>> If you need any more help please ask.
    >>> I hope I'm not harrasing you too much :)
    >>>> --
    >>>> Ueimor
    >>>>
    >>> Have a nice day
    >>> Dushan
    >>>
    >> ...
    >>
    > Have a nice day
    > Dushan
    >


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