[mythtv-users] MythBackend Suddenly swamping CPU on system

[Keith Pyle]

On 06/30/12 21:03, Ben Kamen wrote:
> top - 20:22:59 up 1 day,  2:24,  1 user,  load average: 13.11, 10.50, 6.42
> Tasks: 225 total,   4 running, 221 sleeping,   0 stopped,   0 zombie
> Cpu0  : 51.3%us, 47.7%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  1.1%si,  0.0%st
> Cpu1  : 10.1%us, 88.2%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  1.7%si,  0.0%st
> Cpu2  : 17.4%us, 81.4%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  1.3%si,  0.0%st
> Cpu3  : 24.1%us, 75.1%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  0.8%si,  0.0%st
> Mem:   2052856k total,  1737364k used,   315492k free,    66484k buffers
> Swap:  4193264k total,        0k used,  4193264k free,   899676k cached
>
>     PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>    9739 root      20   0 1744m  22m 8144 S 262.8  1.1  19:19.65/usr/bin/mythbackend --daemon --logpath /var/log/mythtv/  --pid
>       9 root      20   0     0    0    0 R 44.1  0.0  11:33.92 [ksoftirqd/1]
>      13 root      20   0     0    0    0 S 25.5  0.0  56:39.53 [ksoftirqd/2]
>      17 root      20   0     0    0    0 S 24.5  0.0  12:39.16 [ksoftirqd/3]
>       4 root      20   0     0    0    0 S  8.6  0.0  21:41.86 [ksoftirqd/0]
>
>
> This started around 7pm CDT for me.
>
> No drive lights going crazy, no network activity
>
>     -Ben
I had the same problem on my mythbackend system - and on two other Linux 
systems not running Myth.  On the non-Myth systems, running Firefox 
would trigger the high CPU load and show substantial time for ksoftirqd, 
like above.  Two of these systems are running a Gentoo 3.2.4 kernel, and 
the third is running Gentoo 3.2.6.  While I cannot pinpoint the time 
each started exactly, it does seem to correspond to the leap second 
today (1900 Central Time):

Jun 30 18:59:59 somesys kernel: [1947231.441500] Clock: inserting leap 
second 23:59:60 UTC

A reboot was required on each to clear the problem.

This smells like a kernel bug:
http://comments.gmane.org/gmane.linux.kernel/1321070

https://lkml.org/lkml/2012/6/30/122

http://serverfault.com/questions/403732/anyone-else-experiencing-high-rates-of-linux-server-crashes-during-a-leap-second


Keith
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