Re: [ANNOUNCE] 4.4-rc6-rt1

[Sebastian Andrzej Siewior]

* Mike Galbraith | 2016-01-01 08:19:41 [+0100]:

>>   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                      
>>     3 root      -2   0       0      0      0 S  37.3  0.0 307:52.44 ksoftirqd/0                  
>>    32 root      -2   0       0      0      0 S  37.3  0.0 308:08.72 ksoftirqd/2                  
>>    42 root      -2   0       0      0      0 R  37.3  0.0 308:32.84 ksoftirqd/3                  
>>    22 root      -2   0       0      0      0 S  26.9  0.0 222:29.82 ksoftirqd/1                  
>>     1 root      20   0   46628   6980   4976 S   1.3  0.2   0:13.98 systemd                      
>> 22358 williams  20   0  159980   4552   3780 R   1.0  0.1   0:00.39 top       
>
>Heh, I didn't notice immediately because I throttle nohz, am seeing
>only tiny utilization (but nohz idle isn't working).  With throttle
>patch removed, box is screaming, expires=4294990471 pokes eyeball.

This is due to NO_HZ as far as I can tell. My AMD A10 in idle mode has
0.7% utilisation of ksoftirqd/ with CONFIG_HZ_PERIODIC and with
CONFIG_NO_HZ_FULL it shows about 25% on all CPU threads.

Sebastian