Opened 9 years ago
Closed 9 years ago
#15420 closed defect (worksforme)
Running a VM on Linux forces the kernel to call exit_dns_resolver a lot
| Reported by: | rtvd | Owned by: | |
|---|---|---|---|
| Component: | other | Version: | VirtualBox 5.0.20 |
| Keywords: | high cpu usage exit_dns_resolver | Cc: | |
| Guest type: | all | Host type: | Linux |
Description (last modified by )
I have a Linux system with VirtualBox 5.0.20 r106931.
Starting any VM (either Linux or Illumos) shows that a lot of time is spent in a strange part of Linux kernel, the "exit_dns_resolver" function. It is so severe that approximately 80-90% is spent just in that function.
As soon as I stop the VMs the situation returns back to norm.
perf record shows the following traces:
32.70% 32.70% EMT-0 [kernel.kallsyms] [k] exit_dns_resolver
|
---exit_dns_resolver
|
|--99.71%-- __GI___ioctl
| |
| |--99.65%-- 0x104492
| | 0x92eb4
| | 0x8fdbf
| | 0xfe7ec
| | 0xfff1c
| | 0x17b35c
| | start_thread
| --0.35%-- [...]
--0.29%-- [...]
27.18% 27.18% EMT-1 [kernel.kallsyms] [k] exit_dns_resolver
|
---exit_dns_resolver
|
|--99.71%-- __GI___ioctl
| |
| |--99.65%-- 0x104492
| | 0x92eb4
| | 0x8fdbf
| | 0xfe7ec
| | 0xfff1c
| | 0x17b35c
| | start_thread
| --0.35%-- [...]
--0.29%-- [...]
26.52% 26.52% EMT-2 [kernel.kallsyms] [k] exit_dns_resolver
|
---exit_dns_resolver
|
|--99.68%-- __GI___ioctl
| |
| |--99.44%-- 0x104492
| | 0x92eb4
| | 0x8fdbf
| | 0xfe7ec
| | 0xfff1c
| | 0x17b35c
| | start_thread
| |
| --0.56%-- SUPR3CallVMMR0Ex
| |
| |--79.82%-- 0xfd6ab
| | 0xfe583
| | 0x8fcb5
| | 0xfe7ec
| | 0xfff1c
| | 0x17b35c
| | start_thread
| |
| --20.18%-- 0x4a23
| |
| |--99.86%-- 0x4ffb
| | 0xf1803
| | TMR3TimerQueuesDo
| | |
| | |--91.19%-- 0xfd5b9
| | | 0xfe583
| | | 0x8fcb5
| | | 0xfe7ec
| | | 0xfff1c
| | | 0x17b35c
| | | start_thread
| | |
| | --8.81%-- 0x8f00f
| | |
| | |--93.36%-- 0x92f2b
| | | 0x8fdbf
| | | 0xfe7ec
| | | 0xfff1c
| | | 0x17b35c
| | | start_thread
| | |
| | --6.64%-- 0x8f9bf
| | 0xfe7ec
| | 0xfff1c
| | 0x17b35c
| | start_thread
| --0.14%-- [...]
--0.32%-- [...]
Attachments (2)
Change History (7)
by , 9 years ago
comment:1 by , 9 years ago
| Description: | modified (diff) |
|---|
comment:2 by , 9 years ago
What is the CPU load on the host and what is the guest doing at this time? Is the guest idle?
comment:3 by , 9 years ago
At the moment there is no evidence that this is a VBox bug at all. In my Linux kernel, exit_dns_resolver is the last address in the Linux kernel text segment. When a VM is executed, code in the vboxdrv kernel module is called. I assume that perf record just isn't aware of any symbol inside that driver and uses the last known text code symbol for such VM calls.
comment:4 by , 9 years ago
Which command line did you use to gather + display the data -- just perf record -a and perf annotate without any further parameters?
VBox.log of Illumos