# High CPU for migration/x

## Plumbo

Hi,

Not sure where to put this, but as this problem started with a new kernel I might as well try here.

For gentoo-sources >= 3.0.7 I'm seeing some insane cputimes for the migration/x process:

```

top

   23 root      RT   0     0    0    0 S    0  0.0 101:42.85 migration/6                               

   25 root      20   0     0    0    0 S    0  0.0   0:00.04 ksoftirqd/6                               

   26 root      RT   0     0    0    0 S    0  0.0 140:05.32 migration/7                               

   27 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/7:0                               

   28 root      20   0     0    0    0 S    0  0.0   0:00.03 ksoftirqd/7                               

   29 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/8                               

   30 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/8:0                               

   31 root      20   0     0    0    0 S    0  0.0   0:00.01 ksoftirqd/8                               

   32 root      RT   0     0    0    0 S    0  0.0 103:15.51 migration/9                               

   33 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/9:0                               

   34 root      20   0     0    0    0 S    0  0.0   0:00.00 ksoftirqd/9                               

   35 root      RT   0     0    0    0 S    0  0.0 126:50.53 migration/10 

ps axo comm,user,pcpu --sort=-pcpu

COMMAND         USER     %CPU

migration/7     root     92.5

migration/10    root     83.7

migration/9     root     68.1

migration/6     root     67.1

X               root      5.5
```

The migration process is responsible for migrating processes between cores, and the problem appears a couple of minutes after booting, or when the system is under load.  Once it's started, it stays that way, and soon all migration/x processes is under the same high cpuload.

This is apparent when monitoring with ps/top and similar, but the cpuload itself isn't traceble. Frequency scaling does not kick in, and the system is not suffering from lag of any sort, indicating that it is the monitoring itself that's at fault.

My kernel configs are exactly the same for 3.0.6 and 3.0.7, and I've tried up to 3.1.4 with no luck.

Does anyone else suffer from this?  Any ideas?

----------

## Plumbo

It seems like this affects cpu frequency-scaling as well, so I did a bisect and opened a bug.

https://bugs.gentoo.org/show_bug.cgi?id=394487

----------

