virt-top - 'top'-like utility for virtualization stats
virt-top is a top(1)-like utility for showing stats of virtualized
domains. Many keys and command line options are the same as for
It uses libvirt so it is capable of showing stats across a variety of
different virtualization systems.
-1 Display physical CPUs by default (instead of domains). When virt-
top is running, use the 1 key to toggle between physical CPUs and
-2 Display network interfaces by default (instead of domains). When
virt-top is running, use the 2 key to toggle between network
interfaces and domains display.
-3 Display block devices (virtual disks) by default (instead of
domains). When virt-top is running, use the 3 key to toggle
between block devices and domains display.
-b Batch mode. In this mode keypresses are ignored.
-c uri or --connect uri
Connect to the libvirt URI given.
To connect to QEMU/KVM you would normally do -c qemu:///system
To connect to Xen on the same host, do -c xen:///
To connect to libvirtd on a remote machine you would normally do -c
If this option is not given then virt-top connects by default to
whatever is the default hypervisor for libvirt, although this can
be overridden by setting environment variables.
See the libvirt documentation at <http://libvirt.org/uri.php> for
Set the delay between screen updates in seconds. The default is
3.0 seconds. You can change this while virt-top is running by
pressing either s or d key.
Set the number of iterations to run. The default is to run
Set the sort order to one of: cpu (sort by %CPU used), mem (sort by
total memory), time (sort by total time), id (sort by domain ID),
name (sort by domain name), netrx (sort by network received bytes),
nettx (sort by network transmitted bytes), blockrdrq (sort by block
device [disk] read requests), blockwrrq (sort by block device
[disk] write requests).
While virt-top is running you can change the sort order using keys
P (cpu), M (memory), T (total time), N (domain ID), F
(interactively select the sort field).
-s Secure mode. Currently this does nothing.
Set the time in seconds between updates of the historical %CPU at
the top right of the display.
Write the statistics to file file.csv. First a header is written
showing the statistics being recorded in each column, then one line
is written for each screen update. The CSV file can be loaded
directly by most spreadsheet programs.
Currently the statistics which this records vary between releases
of virt-top (but the column headers will stay the same, so you can
use those to process the CSV file).
Not every version of virt-top supports CSV output - it depends how
the program was compiled (see README file in the source
distribution for details).
To save space you can compress your CSV files (if your shell
supports this feature, eg. bash):
virt-top --csv >(gzip -9 > output.csv.gz)
You can use a similar trick to split the CSV file up. In this
example the CSV file is split every 1000 lines into files called
output.csv.00, output.csv.01 etc.
virt-top --csv >(split -d -l 1000 - output.csv.)
Disable domain CPU stats in CSV output.
Disable domain memory stats in CSV output.
Disable domain block device stats in CSV output.
Disable domain network interface stats in CSV output.
Send debug and error messages to filename. To send error messages
to syslog you can do:
virt-top --debug >(logger -t virt-top)
See also REPORTING BUGS below.
Read filename as the init file instead of the default which is
$HOME/.virt-toprc. See also INIT FILE below.
Do not read any init file.
Script mode. There will be no user interface. This is most useful
when used together with the --csv and -n options.
Stream mode. All output is sent to stdout. This can be used from
shell scripts etc. There is no user interface.
Show I/O statistics in Bytes. Default is shown in the number of
The program will exit at the time given.
The time may be given in one of the following formats:
End time is the date and time given.
End time is the time given, today.
End time is HH hours, MM minutes, SS seconds in the future
(counted from the moment that program starts).
End time is secs seconds in the future.
For example to run the program for 3 minutes you could do:
virt-top --end-time +00:03:00
virt-top --end-time +180
Not every version of virt-top supports this option - it depends how
the program was compiled (see README file in the source
distribution for details).
Display usage summary.
Display version number and exit.
Note that keys are case sensitive. For example use upper-case P (shift
P) to sort by %CPU. ^ before a key means a Ctrl key, so ^L is Ctrl L.
space or ^L
Updates the display.
q Quits the program.
h Displays help.
s or d
Change the delay between screen updates.
B Toggle Block I/O statistics so they are shown in either bytes or
0 (number 0)
Show the normal list of domains display.
1 (number 1)
Toggle into showing physical CPUs. If pressed again toggles back
to showing domains (the normal display).
2 Toggle into showing network interfaces. If pressed again toggles
back to showing domains.
3 Toggle into showing block devices (virtual disks). If pressed
again toggles back to showing domains.
P Sort by %CPU.
M Sort by total memory. Note that this shows the total memory
allocated to the guest, not the memory being used.
T Sort by total time.
N Sort by domain ID.
F Select the sort field interactively (there are other sort fields
you can choose using this key).
W This creates or overwrites the init file with the current settings.
This key is disabled if --no-init-file was specified on the command
line or if overwrite-init-file false is given in the init file.
When virt-top starts up, it reads initial settings from the file
.virt-toprc in the user's home directory.
The name of this file may be overridden using the --init-file filename
command line option or may be disabled entirely using --no-init-file.
The init file has a simple format. Blank lines and comments beginning
with # are ignored. Everything else is a set of key value pairs,
Sets the major display mode to one of task (tasks, the default),
pcpu (physical CPUs), block (block devices), or net (network
Sets the delay between display updates in seconds.
Sets the historical CPU delay in seconds.
Sets the number of iterations to run before we exit. Setting this
to -1 means to run continuously.
Sets the sort order. The option names are the same as for the
command line -o option.
Sets the default connection URI.
Sets the default filename to use for debug and error messages.
Enables CSV output to the named file.
Enable or disable domain CPU stats in CSV output.
Enable or disable domain memory stats in CSV output.
Enable or disable domain block device stats in CSV output.
Enable or disable domain network interface stats in CSV output.
Sets batch mode.
Sets secure mode.
Sets script mode.
Sets stream mode.
Show block device statistics in bytes.
Set the time at which the program exits. See above for the time
If set to false then the W key will not overwrite the init file.
Note that in the current implementation, options specified in the init
file override options specified on the command line. This is a bug and
this behaviour may change in the future.
Block I/O statistics
This I/O value is the amount of I/O since the previous iteration of
virt-top. To calculate speed of I/O, you should divide the number by
NETWORK RX BYTES AND PACKETS
Libvirt/virt-top has no way to know that a packet transmitted to a
guest was received (eg. if the guest is not listening). In the network
RX stats, virt-top reports the packets transmitted to the guest, on the
basis that the guest might receive them.
In particular this includes broadcast packets. Because of the way that
Linux bridges work, if the guest is connected to a bridge, it will
probably see a steady "background noise" of RX packets even when the
network interface is idle or down. These are caused by STP packets
generated by the bridge.
DEBUGGING LIBVIRT ISSUES
virt-top tries to turn libvirt errors into informative messages.
However if libvirt initialization fails then this is not possible.
Instead you will get an obscure error like:
libvir: error : Unknown failure
Fatal error: exception Libvirt.Virterror(...)
To see the cause of libvirt errors in more detail, enable libvirt
debugging by setting this environment variable:
top(1), virsh(1), <http://www.libvirt.org/ocaml/>,
Richard W.M. Jones <rjones @ redhat . com>
(C) Copyright 2007-2011 Red Hat Inc., Richard W.M. Jones
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
675 Mass Ave, Cambridge, MA 02139, USA.
Bugs can be viewed on the Red Hat Bugzilla page:
If you find a bug in virt-top, please follow these steps to report it:
1. Check for existing bug reports
Go to <https://bugzilla.redhat.com/> and search for similar bugs.
Someone may already have reported the same bug, and they may even
have fixed it.
2. Capture debug and error messages
virt-top --debug virt-top.log
and keep virt-top.log. It contains error messages which you should
submit with your bug report.
3. Get version of virt-top and version of libvirt.
If you can get the precise version of libvirt you are using then
that too is helpful.
4. Submit a bug report.
Go to <https://bugzilla.redhat.com/> and enter a new bug. Please
describe the problem in as much detail as possible.
Remember to include the version numbers (step 3) and the debug
messages file (step 2).
5. Assign the bug to rjones @ redhat.com
Assign or reassign the bug to rjones @ redhat.com (without the
spaces). You can also send me an email with the bug number if you
want a faster response.