[X2Go-User] x2goserver causes increase in ksoftirqd/x CPU usage

[Rett Walters]

Hello:

I have two machines running Archlinux with x2goserver running from arch
repository packages that both exhibit abnormally high CPU usage in
ksoftirqd/x (where x=the cpu core #).  Here is an example top output
showing the usage while idle - ksoftirqd is always the top user of CPU when
the system is idle:

top - 13:27:42 up 27 days, 16:27,  8 users,  load average: 0.84, 0.63, 0.49
Tasks: 326 total,   1 running, 325 sleeping,   0 stopped,   0 zombie
%Cpu(s):   0.6/0.7
1[||
]
GiB Mem : 26.9/15.574
[
]
GiB Swap:  5.4/16.000
[
]

  PID USER      PR  NI    VIRT    RES  %CPU %MEM     TIME+ S COMMAND
   45 root      20   0    0.0m   0.0m   4.0  0.0 478:55.34 S ksoftirqd/7
   65 root      20   0    0.0m   0.0m   2.6  0.0 417:08.28 S ksoftirqd/11
   25 root      20   0    0.0m   0.0m   2.0  0.0 109:05.16 S ksoftirqd/3
   60 root      20   0    0.0m   0.0m   2.0  0.0 523:14.28 S ksoftirqd/10
 9180 rettw     20   0 2663.9m 1.321g   2.0  8.5  16:08.16 S VBoxHeadless
   50 root      20   0    0.0m   0.0m   1.3  0.0 527:10.22 S ksoftirqd/8
 9236 rettw     20   0 1588.0m 371.6m   1.3  2.3   2:29.45 S VBoxHeadless
    3 root      20   0    0.0m   0.0m   0.7  0.0 392:21.72 S ksoftirqd/0
   30 root      20   0    0.0m   0.0m   0.7  0.0 133:12.11 S ksoftirqd/4
   55 root      20   0    0.0m   0.0m   0.7  0.0 463:32.57 S ksoftirqd/9
 1005 rettw     20   0 3058.8m  66.6m   0.7  0.4  29:58.26 S kwin
 8502 root      20   0   35.1m   3.7m   0.7  0.0   0:13.56 R top
30713 rettw     20   0  605.3m  22.2m   0.7  0.1   6:45.55 S konsole
    1 root      20   0   33.6m   4.1m   0.0  0.0   0:18.42 S systemd
    2 root      20   0    0.0m   0.0m   0.0  0.0   0:00.32 S kthreadd

If I stop the x2goserver process, the ksoftirqd processes drop down to
almost nothing.    This seems to coincide with the 3.18 and 3.19 linux
kernel series.

Could this be some sort of interaction between x2goserver and the kernel?

System specs:

i7-5930k w/16G DDR4 2133 RAM
MSI X99 SLI-Plus
GTX 470
LSI SAS2008 Disk controller card
Archlinux latest packages - kernel version 3.18.6-1-ARCH
KDE, Xorg, Nvidia binary blob video driver

Second system with the issue:

i7-3930k w/16G DDR3 1600 RAM
Asus Sabertooth X79
GTX 970
Archlinux latest packages - kernel version 3.19.2-1-ARCH
KDE, Xorg, Nvidia binary blob video driver

I have several other arch systems as well, but none of them have x2goserver
running on them and therefore don't exhibit the ksoftirqd cpu usage.

Archlinux x2goserver package version:  extra/x2goserver 4.0.1.19-2

Doesn't seem to impact the system much, just thought it seemed a bit
abnormal for this to generate that much soft irq activity.


-- 
Rett Walters
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