=head1 NAME

virt-top - 'top'-like utility for virtualization stats

=head1 SUMMARY

virt-top [-options]

=head1 DESCRIPTION

virt-top is a L<top(1)>-like utility for showing stats of virtualized
domains.  Many keys and command line options are the same as for
ordinary I<top>.

It uses libvirt so it is capable of showing stats across a variety of
different virtualization systems.

=head1 OPTIONS

=over 4

=item B<-1>

Display physical CPUs by default (instead of domains).

Under each domain column, two numbers are shown.  The first is
the percentage of the physical CPU used by the domain and the
hypervisor together.  The second is the percentage used by just
the domain.

When virt-top is running, use the I<1> key to toggle
between physical CPUs and domains display.

=item B<-2>

Display network interfaces by default (instead of domains).
When virt-top is running, use the I<2> key to toggle
between network interfaces and domains display.

=item B<-3>

Display block devices (virtual disks) by default (instead of domains).
When virt-top is running, use the I<3> key to toggle
between block devices and domains display.

=item B<-b>

Batch mode.  In this mode keypresses are ignored.

=item B<-c uri> or B<--connect uri>

Connect to the libvirt URI given.

To connect to QEMU/KVM you would normally do I<-c qemu:///system>

To connect to Xen on the same host, do I<-c xen:///>

To connect to libvirtd on a remote machine you would normally do
I<-c qemu://host/system>

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 L<http://libvirt.org/uri.html>
for further information.

=item B<-d delay>

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 I<s> or I<d> key.

=item B<-n iterations>

Set the number of iterations to run.  The default
is to run continuously.

=item B<-o sort>

Set the sort order to one of:
B<cpu> (sort by %CPU used),
B<mem> (sort by total memory),
B<time> (sort by total time),
B<id> (sort by domain ID),
B<name> (sort by domain name),
B<netrx> (sort by network received bytes),
B<nettx> (sort by network transmitted bytes),
B<blockrdrq> (sort by block device [disk] read requests),
B<blockwrrq> (sort by block device [disk] write requests).

While virt-top is running you can change the sort
order using keys I<P> (cpu), I<M> (memory),
I<T> (total time), I<N> (domain ID),
I<F> (interactively select the sort field).

=item B<-s>

Secure mode.  Currently this does nothing.

=item B<--hist-cpu secs>

Set the time in seconds between updates of the historical
%CPU at the top right of the display.

=item B<--csv file.csv>

Write the statistics to file I<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).

To save space you can compress your CSV files (if your shell supports
this feature, eg. I<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
I<output.csv.00>, I<output.csv.01> etc.

 virt-top --csv >(split -d -l 1000 - output.csv.)

=item B<--no-csv-cpu>

Disable domain CPU stats in CSV output.

=item B<--no-csv-mem>

Disable domain memory stats in CSV output.

=item B<--no-csv-block>

Disable domain block device stats in CSV output.

=item B<--no-csv-net>

Disable domain network interface stats in CSV output.

=item B<--debug filename>

Send debug and error messages to I<filename>.
To send error messages to syslog you can do:

 virt-top --debug >(logger -t virt-top)

See also REPORTING BUGS below.

=item B<--init-file filename>

Read I<filename> as the init file instead of the default which is
I<$HOME/.virt-toprc>.  See also INIT FILE below.

=item B<--no-init-file>

Do not read any init file.

=item B<--script>

Script mode.  There will be no user interface.  This is most useful
when used together with the I<--csv> and I<-n> options.

=item B<--stream>

Stream mode.  All output is sent to stdout.  This can be used from
shell scripts etc.  There is no user interface.

=item B<--block-in-bytes>

Show I/O statistics in Bytes. Default is shown in the number of Requests.

=item B<--end-time time>

The program will exit at the I<time> given.

The time may be given in one of the following formats:

=over 4

=item I<YYYY-MM-DD HH:MM:SS>

End time is the date and time given.

=item I<HH:MM:SS>

End time is the time given, today.

=item I<+HH:MM:SS>

End time is HH hours, MM minutes, SS seconds in the future (counted
from the moment that program starts).

=item I<+secs>

End time is I<secs> seconds in the future.

=back

For example to run the program for 3 minutes you could do:

 virt-top --end-time +00:03:00

or:

 virt-top --end-time +180

Not every version of virt-top supports this option - it depends how the
program was compiled (see I<README> file in the source distribution
for details).

=item B<--help>

Display usage summary.

=item B<--version>

Display version number and exit.

=back

=head1 KEYS

Note that keys are case sensitive.  For example use upper-case I<P>
(shift P) to sort by %CPU.  I<^> before a key means a Ctrl key, so
I<^L> is Ctrl L.

=over 4

=item I<space> or I<^L>

Updates the display.

=item I<q>

Quits the program.

=item I<h>

Displays help.

=item I<s> or I<d>

Change the delay between screen updates.

=item I<B>

Toggle Block I/O statistics so they are shown in either bytes or requests.

=item I<0> (number 0)

Show the normal list of domains display.

=item I<1> (number 1)

Toggle into showing physical CPUs.  If pressed
again toggles back to showing domains (the normal
display).

=item I<2>

Toggle into showing network interfaces.  If pressed
again toggles back to showing domains.

=item I<3>

Toggle into showing block devices (virtual disks).  If pressed again
toggles back to showing domains.

=item I<P>

Sort by %CPU.

=item I<M>

Sort by total memory.  Note that this shows the total memory
allocated to the guest, not the memory being used.

=item I<T>

Sort by total time.

=item I<N>

Sort by domain ID.

=item I<F>

Select the sort field interactively (there are other
sort fields you can choose using this key).

=item I<W>

This creates or overwrites the init file with the current settings.

This key is disabled if I<--no-init-file> was specified on the
command line or if I<overwrite-init-file false> is given in
the init file.

=back

=head1 INIT FILE

When virt-top starts up, it reads initial settings from the
file I<.virt-toprc> in the user's home directory.

The name of this file may be overridden using the I<--init-file
filename> command line option or may be disabled entirely using
I<--no-init-file>.

The init file has a simple format.  Blank lines and comments
beginning with I<#> are ignored.  Everything else is a set of
I<key value> pairs, described below.

=over 4

=item B<display> I<task|pcpu|block|net>

Sets the major display mode to one of I<task> (tasks, the
default), I<pcpu> (physical CPUs), I<block> (block devices),
or I<net> (network interfaces).

=item B<delay> I<secs>

Sets the delay between display updates in seconds.

=item B<hist-cpu> I<secs>

Sets the historical CPU delay in seconds.

=item B<iterations> I<n>

Sets the number of iterations to run before we exit.  Setting
this to I<-1> means to run continuously.

=item B<sort> I<cpu|mem|time|id|name|...>

Sets the sort order.  The option names are the same as for
the command line I<-o> option.

=item B<connect> I<uri>

Sets the default connection URI.

=item B<debug> I<filename>

Sets the default filename to use for debug and error messages.

=item B<csv> I<filename>

Enables CSV output to the named file.

=item B<csv-cpu> I<true|false>

Enable or disable domain CPU stats in CSV output.

=item B<csv-mem> I<true|false>

Enable or disable domain memory stats in CSV output.

=item B<csv-block> I<true|false>

Enable or disable domain block device stats in CSV output.

=item B<csv-net> I<true|false>

Enable or disable domain network interface stats in CSV output.

=item B<batch> I<true|false>

Sets batch mode.

=item B<secure> I<true|false>

Sets secure mode.

=item B<script> I<true|false>

Sets script mode.

=item B<stream> I<true|false>

Sets stream mode.

=item B<block-in-bytes> I<true|false>

Show block device statistics in bytes.

=item B<end-time> I<time>

Set the time at which the program exits.  See above for the
time formats supported.

=item B<overwrite-init-file> I<false>

If set to I<false> then the I<W> key will not overwrite the
init file.

=back

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.

=head1 COLUMN HEADINGS

=over 4

=item B<%CPU>

Percentage of CPU used.  As with L<top(1)>, 100% means that
all physical CPUs are being fully used.

=item B<DEVICE>

The block device name.

=item B<DOMAIN>

=item B<NAME>

The name of the libvirt domain.

=item B<ID>

The libvirt domain ID.

=item B<INTERFACE>

The network interface name.

=item B<%MEM>

The percentage of host memory assigned to the guest.

=item B<PHYCPU>

The physical CPU.

=item B<RDBY>

Disk bytes read since last displayed.

=item B<RDRQ>

Disk read requests since last displayed.

=item B<RXBY>

Network bytes received since last displayed.

=item B<RXPK>

Network packets received since last displayed.

=item B<S>

The state of the domain, one of:

=over 4

=item B<?>

Unknown.

=item B<R>

Running.

=item B<S>

Blocked.

=item B<P>

Paused.

=item B<D>

=item B<O>

Shutdown.

=item B<X>

Crashed.

=item B<M>

Suspended by guest power management.

=back

=item B<TIME>

Total CPU time used.

=item B<TXBY>

Network bytes transmitted since last displayed.

=item B<TXPK>

Network packets transmitted since last displayed.

=item B<WRBY>

Disk bytes written since last displayed.

=item B<WRRQ>

Disk write requests since last displayed.

=back

=head1 NOTES

=head2 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 delay secs.

=head2 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.

=head2 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:

 export LIBVIRT_DEBUG=1

=head1 SEE ALSO

L<top(1)>,
L<virsh(1)>,
L<http://www.libvirt.org/ocaml/>,
L<http://www.libvirt.org/>,
L<http://people.redhat.com/~rjones/>,
L<http://caml.inria.fr/>

=head1 AUTHORS

Richard W.M. Jones <rjones @ redhat . com>

=head1 COPYRIGHT

(C) Copyright 2007-2012 Red Hat Inc., Richard W.M. Jones
http://libvirt.org/

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.

=head1 REPORTING BUGS

Bugs can be viewed on the Red Hat Bugzilla page:
L<https://bugzilla.redhat.com/>.

If you find a bug in virt-top, please follow these steps to report it:

=over 4

=item 1. Check for existing bug reports

Go to L<https://bugzilla.redhat.com/> and search for similar bugs.
Someone may already have reported the same bug, and they may even
have fixed it.

=item 2. Capture debug and error messages

Run

 virt-top --debug virt-top.log

and keep I<virt-top.log>.  It contains error messages which you
should submit with your bug report.

=item 3. Get version of virt-top and version of libvirt.

Use:

 virt-top --version

If you can get the precise version of libvirt you are using
then that too is helpful.

=item 4. Submit a bug report.

Go to L<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).

=item 5. Assign the bug to rjones @ redhat.com

Assign or reassign the bug to B<rjones @ redhat.com> (without the
spaces).  You can also send me an email with the bug number if you
want a faster response.

=back
