linux/tools/kvm/kvm_stat/kvm_stat.txt
Stefan Raspl 883d25e70b tools/kvm_stat: fix fields filter for child events
The fields filter would not work with child fields, as the respective
parents would not be included. No parents displayed == no childs displayed.
To reproduce, run on s390 (would work on other platforms, too, but would
require a different filter name):
- Run 'kvm_stat -d'
- Press 'f'
- Enter 'instruct'
Notice that events like instruction_diag_44 or instruction_diag_500 are not
displayed - the output remains empty.
With this patch, we will filter by matching events and their parents.
However, consider the following example where we filter by
instruction_diag_44:

  kvm statistics - summary
                   regex filter: instruction_diag_44
   Event                                         Total %Total CurAvg/s
   exit_instruction                                276  100.0       12
     instruction_diag_44                           256   92.8       11
   Total                                           276              12

Note that the parent ('exit_instruction') displays the total events, but
the childs listed do not match its total (256 instead of 276). This is
intended (since we're filtering all but one child), but might be confusing
on first sight.

Signed-off-by: Stefan Raspl <raspl@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-05-24 21:27:17 +02:00

106 lines
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kvm_stat(1)
===========
NAME
----
kvm_stat - Report KVM kernel module event counters
SYNOPSIS
--------
[verse]
'kvm_stat' [OPTION]...
DESCRIPTION
-----------
kvm_stat prints counts of KVM kernel module trace events. These events signify
state transitions such as guest mode entry and exit.
This tool is useful for observing guest behavior from the host perspective.
Often conclusions about performance or buggy behavior can be drawn from the
output.
While running in regular mode, use any of the keys listed in section
'Interactive Commands' below.
Use batch and logging modes for scripting purposes.
The set of KVM kernel module trace events may be specific to the kernel version
or architecture. It is best to check the KVM kernel module source code for the
meaning of events.
INTERACTIVE COMMANDS
--------------------
[horizontal]
*b*:: toggle events by guests (debugfs only, honors filters)
*c*:: clear filter
*f*:: filter by regular expression
:: *Note*: Child events pull in their parents, and parents' stats summarize
all child events, not just the filtered ones
*g*:: filter by guest name/PID
*h*:: display interactive commands reference
*o*:: toggle sorting order (Total vs CurAvg/s)
*p*:: filter by guest name/PID
*q*:: quit
*r*:: reset stats
*s*:: set update interval
*x*:: toggle reporting of stats for child trace events
:: *Note*: The stats for the parents summarize the respective child trace
events
Press any other key to refresh statistics immediately.
OPTIONS
-------
-1::
--once::
--batch::
run in batch mode for one second
-l::
--log::
run in logging mode (like vmstat)
-t::
--tracepoints::
retrieve statistics from tracepoints
-d::
--debugfs::
retrieve statistics from debugfs
-i::
--debugfs-include-past::
include all available data on past events for debugfs
-p<pid>::
--pid=<pid>::
limit statistics to one virtual machine (pid)
-g<guest>::
--guest=<guest_name>::
limit statistics to one virtual machine (guest name)
-f<fields>::
--fields=<fields>::
fields to display (regex), "-f help" for a list of available events
-h::
--help::
show help message
SEE ALSO
--------
'perf'(1), 'trace-cmd'(1)
AUTHOR
------
Stefan Hajnoczi <stefanha@redhat.com>