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libvirt/tools/virt-admin.pod
Erik Skultety 510991b65a virt-admin: Introduce srv-threadpool-info and srv-threadpool-set commands 
Wire up the server threadpool tunable APIs to virt-admin client. Also, provide
a man page for both commands.

Signed-off-by: Erik Skultety <eskultet@redhat.com>
2016-04-18 17:08:11 +02:00

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=head1 NAME
virt-admin - daemon administration interface
=head1 SYNOPSIS
B<virt-admin> [I<OPTION>]... [I<COMMAND_STRING>]
B<virt-admin> [I<OPTION>]... I<COMMAND> [I<ARG>]...
=head1 DESCRIPTION
The B<virt-admin> program is the main administration interface for modifying
the libvirt daemon configuration at runtime, changing daemon behaviour as well
as for monitoring and managing all clients connected to the daemon.
The basic structure of most virt-admin usage is:
virt-admin [OPTION]... <command> [ARG]...
Where I<command> is one of the commands listed below.
The B<virt-admin> program can be used either to run one I<COMMAND> by giving the
command and its arguments on the shell command line, or a I<COMMAND_STRING>
which is a single shell argument consisting of multiple I<COMMAND> actions
and their arguments joined with whitespace, and separated by semicolons
between commands. Within I<COMMAND_STRING>, virt-admin understands the
same single, double, and backslash escapes as the shell, although you must
add another layer of shell escaping in creating the single shell argument.
If no command is given in the command line, B<virt-admin> will then start a minimal
interpreter waiting for your commands, and the B<quit> command will then exit
the program.
The B<virt-admin> program understands the following I<OPTIONS>.
=over 4
=item B<-c>, B<--connect> I<URI>
Connect to the specified I<URI>, as if by the B<connect> command,
instead of the default connection.
=item B<-d>, B<--debug> I<LEVEL>
Enable debug messages at integer I<LEVEL> and above. I<LEVEL> can
range from 0 to 4 (default). See the documentation of B<VIRT_ADMIN_DEBUG>
environment variable below for the description of each I<LEVEL>.
=item B<-h>, B<--help>
Ignore all other arguments, and behave as if the B<help> command were
given instead.
=item B<-l>, B<--log> I<FILE>
Output logging details to I<FILE>.
=item B<-q>, B<--quiet>
Avoid extra informational messages.
=item B<-v>, B<--version[=short]>
Ignore all other arguments, and prints the version of the libvirt library
virt-admin is coming from
=item B<-V>, B<--version=long>
Ignore all other arguments, and prints the version of the libvirt library
virt-admin is coming from.
=back
=head1 NOTES
Running B<virt-admin> requires root privileges due to the
communications channels used to talk to the daemon. Consider changing the
I<unix_sock_group> ownership setting to grant access to specific set of users
or modifying I<unix_sock_rw_perms> permissions. Daemon configuration file
provides more information about setting permissions.
=head1 GENERIC COMMANDS
The following commands are generic.
=over 4
=item B<help> [I<command-or-group>]
This lists each of the virt-admin commands. When used without options, all
commands are listed, one per line, grouped into related categories,
displaying the keyword for each group.
To display detailed information for a specific command, use its name as the
option.
=item B<quit>, B<exit>
quit this interactive terminal
=item B<version>
Will print out the version info about which libvirt library was this client
built from. As opposed to I<virsh> client, the output already includes
the version of the daemon.
B<Example>
$ virt-admin version
Compiled against library: libvirt 1.2.21
Using library: libvirt 1.2.21
Running against daemon: 1.2.20
=item B<cd> [I<directory>]
Will change current directory to I<directory>. The default directory
for the B<cd> command is the home directory or, if there is no I<HOME>
variable in the environment, the root directory.
This command is only available in interactive mode.
=item B<pwd>
Will print the current directory.
=item B<connect> [I<URI>]
(Re)-Connect to a daemon's administrating server. The I<URI> parameter
specifies how to connect to the administrating server.
If I<LIBVIRT_ADMIN_DEFAULT_URI> or I<admin_uri_default> (see below) were set,
I<connect> is automatically issued every time a command that requires an
active connection is executed. Note that this only applies if there is no
connection at all or there is an inactive one.
To find the currently used URI, check the I<uri> command documented below.
For remote access see the documentation page at
L<http://libvirt.org/uri.html> on how to make URIs.
=item B<uri>
Prints the administrating server canonical URI, can be useful in shell mode. If
no I<uri> was specified, neither I<LIBVIRT_ADMIN_DEFAULT_URI> or
I<admin_uri_default> were set, libvirtd:///system is used.
=back
=head1 SERVER COMMANDS
Following commands manipulate daemon's server internal configuration.
The I<server> is specified by its name.
=over 4
=item B<srv-threadpool-info> I<server>
Retrieve server's threadpool attributes. These attributes include:
=over 4
=item I<minWorkers>
as the bottom limit to the number of active workers,
=item I<maxWorkers>
as the top limit to the number of active workers,
=item I<nWorkers>
as the current number of workers in the threadpool,
=item I<freeWorkers>
as the current number of workers available for a task,
=item I<prioWorkers>
as the current number of priority workers in the threadpool, and
=item I<jobQueueDepth>
as the current depth of threadpool's job queue.
=back
B<Background>
Each daemon server utilizes a threadpool to accomplish tasks requested by
clients connected to it. Every time a client request arrives to the server,
it checks whether there is a worker available to accomplish the given task or
it should create a new worker for the job (rather than being destroyed, the
worker becomes free once the task is finished). Creating new workers, however,
is only possible when the current number of workers is still below the
configured upper limit.
In addition to these 'standard' workers, a threadpool also contains a special
set of workers called I<priority> workers. Their purpose is to perform tasks
that, unlike tasks carried out by normal workers, are within libvirt's full
control and libvirt guarantees that such a task cannot hang, thus will always
finish. An example of such a task this would be destroying a domain:
$ virsh destroy <domain>.
=item B<srv-threadpool-set> I<server> [I<--min-workers> B<count>]
[I<--max-workers> B<count>] [I<--priority-workers> B<count>]
Change threadpool attributes on a server. Only a fraction of all attributes as
described in I<srv-threadpool-info> is supported for the setter.
=over 4
=item I<--min-workers>
The bottom limit to number of active workers in a threadpool.
=item I<--max-workers>
The upper limit to number of active workers in a threadpool. If used in
combination with option I<--min-workers>, the value for the upper limit has to
be greater than the value for the bottom limit, otherwise the command results
in an error.
=item I<--priority-workers>
The current number of active priority workers in a threadpool.
=back
=back
=head1 ENVIRONMENT
The following environment variables can be set to alter the behaviour
of C<virt-admin>
=over 4
=item VIRT_ADMIN_DEBUG=<0 to 4>
Turn on verbose debugging of virt-admin commands. Valid levels are
=over 4
=item * VIRT_ADMIN_DEBUG=0
DEBUG - Messages at ALL levels get logged
=item * VIRT_ADMIN_DEBUG=1
INFO - Logs messages at levels INFO, NOTICE, WARNING and ERROR
=item * VIRT_ADMIN_DEBUG=2
NOTICE - Logs messages at levels NOTICE, WARNING and ERROR
=item * VIRT_ADMIN_DEBUG=3
WARNING - Logs messages at levels WARNING and ERROR
=item * VIRT_ADMIN_DEBUG=4
ERROR - Messages at only ERROR level gets logged.
=back
=item VIRT_ADMIN_LOG_FILE=C<LOGFILE>
The file to log virt-admin debug messages.
=item LIBVIRT_ADMIN_DEFAULT_URI
The daemon whose admin server to connect to by default. Set this to a URI, in
the same format as accepted by the B<connect> option. This overrides the
default URI set in any client config file.
=item VIRT_ADMIN_HISTSIZE
The number of commands to remember in the command history. The
default value is 500.
=item LIBVIRT_DEBUG=LEVEL
Turn on verbose debugging of all libvirt API calls. Valid levels are
=over 4
=item * LIBVIRT_DEBUG=1
Messages at level DEBUG or above
=item * LIBVIRT_DEBUG=2
Messages at level INFO or above
=item * LIBVIRT_DEBUG=3
Messages at level WARNING or above
=item * LIBVIRT_DEBUG=4
Messages at level ERROR or above
=back
For further information about debugging options consult C<http://libvirt.org/logging.html>
=back
=head1 BUGS
Report any bugs discovered to the libvirt community via the mailing
list C<http://libvirt.org/contact.html> or bug tracker C<http://libvirt.org/bugs.html>.
Alternatively report bugs to your software distributor / vendor.
=head1 AUTHORS
Please refer to the AUTHORS file distributed with libvirt.
Based on the virsh man page.
=head1 COPYRIGHT
Copyright (C) 2015 Red Hat, Inc., and the authors listed in the
libvirt AUTHORS file.
=head1 LICENSE
virt-admin is distributed under the terms of the GNU LGPL v2+.
This is free software; see the source for copying conditions. There
is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE
=head1 SEE ALSO
L<virsh(1)>, L<virt-xml-validate(1)>, L<virt-host-validate(1)>,
L<http://www.libvirt.org/>
=cut
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