VM costs high CPU by sy 100%

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maybeonly
Posts: 2
Joined: 26. Sep 2017, 12:27

VM costs high CPU by sy 100%

Post by maybeonly »

I have two windows guests on a linux host.
Now each VM costs cpu 100% sy (only one vm is shown, the other is stopped)
I tried to update everything by yum update, but nothing works.
top - 18:28:40 up 37 min,  2 users,  load average: 0.90, 0.89, 0.90
Tasks: 185 total,   1 running, 184 sleeping,   0 stopped,   0 zombie
%Cpu0  :  0.0 us, 99.7 sy,  0.0 ni,  0.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :  0.3 us,  0.3 sy,  0.0 ni, 99.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :  0.0 us,  0.3 sy,  0.0 ni, 99.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  :  0.3 us,  0.0 sy,  0.0 ni, 99.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem : 16172052 total, 11229400 free,  4626428 used,   316224 buff/cache
KiB Swap:  8193020 total,  8193020 free,        0 used. 11178284 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                                              
 2892 root      20   0 5876968 4.092g 4.045g S 100.0 26.5  15:40.62 /usr/lib/virtualbox/VBoxHeadless --comment 193 --startvm ******
I've checked its thread by H button in top command, it seems that the main thread (2892) costs the most of cpu
I ran strace on this process and got lots of ioctl as below.
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
sched_yield()                           = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
ioctl(7, _IOC(0, 0x56, 0xc1, 0x00), 0)  = 0
the guest is Windows server 2016, and the host is
[root@storage ~]# uname -a
Linux storage.*** 3.10.0-693.2.2.el7.x86_64 #1 SMP Tue Sep 12 22:26:13 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
[root@storage ~]# VBoxManage --version
5.1.18r114002
Any idea?
Thank you.

I'm sorry for my poor English.
mpack
Site Moderator
Posts: 39156
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Mostly XP

Re: VM costs high CPU by sy 100%

Post by mpack »

CPU time is not used up by magic: look in the task manager of the guest and find out what process is using CPU or I/O time.
maybeonly
Posts: 2
Joined: 26. Sep 2017, 12:27

Re: VM costs high CPU by sy 100%

Post by maybeonly »

mpack wrote:CPU time is not used up by magic: look in the task manager of the guest and find out what process is using CPU or I/O time.
The task manager on windows show nothing but I installed a clean Windows and it works fine now.
Thank you.
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