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The 'perf kvm' subcommand has options that it in turn passes to other perf subcommands such as 'report' and 'record', particularly -i and -o end up setting the same variable that will then be used for 'record's -o and report '-i', which ends up being confusing, leading some to think that both -i and -o can be used with 'report'. Improve the man page to state that -i is used with the post-processing subcommands while -o is used just with 'record' and that to save the output of 'report' one should simply redirect its output to a file. Noticed while reading the https://www.linux-kvm.org/page/Perf_events page. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Steve Dickson <steved@redhat.com> Cc: William Cohen <wcohen@redhat.com> Link: https://lkml.kernel.org/n/tip-tclbttvmgtm525fvmh85f7d9@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
166 lines
5.8 KiB
Plaintext
166 lines
5.8 KiB
Plaintext
perf-kvm(1)
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===========
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NAME
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----
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perf-kvm - Tool to trace/measure kvm guest os
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SYNOPSIS
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--------
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[verse]
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'perf kvm' [--host] [--guest] [--guestmount=<path>
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[--guestkallsyms=<path> --guestmodules=<path> | --guestvmlinux=<path>]]
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{top|record|report|diff|buildid-list} [<options>]
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'perf kvm' [--host] [--guest] [--guestkallsyms=<path> --guestmodules=<path>
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| --guestvmlinux=<path>] {top|record|report|diff|buildid-list|stat} [<options>]
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'perf kvm stat [record|report|live] [<options>]
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DESCRIPTION
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-----------
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There are a couple of variants of perf kvm:
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'perf kvm [options] top <command>' to generates and displays
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a performance counter profile of guest os in realtime
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of an arbitrary workload.
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'perf kvm record <command>' to record the performance counter profile
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of an arbitrary workload and save it into a perf data file. We set the
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default behavior of perf kvm as --guest, so if neither --host nor --guest
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is input, the perf data file name is perf.data.guest. If --host is input,
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the perf data file name is perf.data.kvm. If you want to record data into
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perf.data.host, please input --host --no-guest. The behaviors are shown as
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following:
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Default('') -> perf.data.guest
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--host -> perf.data.kvm
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--guest -> perf.data.guest
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--host --guest -> perf.data.kvm
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--host --no-guest -> perf.data.host
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'perf kvm report' to display the performance counter profile information
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recorded via perf kvm record.
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'perf kvm diff' to displays the performance difference amongst two perf.data
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files captured via perf record.
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'perf kvm buildid-list' to display the buildids found in a perf data file,
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so that other tools can be used to fetch packages with matching symbol tables
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for use by perf report. As buildid is read from /sys/kernel/notes in os, then
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if you want to list the buildid for guest, please make sure your perf data file
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was captured with --guestmount in perf kvm record.
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'perf kvm stat <command>' to run a command and gather performance counter
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statistics.
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Especially, perf 'kvm stat record/report' generates a statistical analysis
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of KVM events. Currently, vmexit, mmio (x86 only) and ioport (x86 only)
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events are supported. 'perf kvm stat record <command>' records kvm events
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and the events between start and end <command>.
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And this command produces a file which contains tracing results of kvm
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events.
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'perf kvm stat report' reports statistical data which includes events
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handled time, samples, and so on.
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'perf kvm stat live' reports statistical data in a live mode (similar to
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record + report but with statistical data updated live at a given display
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rate).
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OPTIONS
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-------
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-i::
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--input=<path>::
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Input file name, for the 'report', 'diff' and 'buildid-list' subcommands.
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-o::
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--output=<path>::
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Output file name, for the 'record' subcommand. Doesn't work with 'report',
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just redirect the output to a file when using 'report'.
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--host::
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Collect host side performance profile.
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--guest::
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Collect guest side performance profile.
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--guestmount=<path>::
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Guest os root file system mount directory. Users mounts guest os
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root directories under <path> by a specific filesystem access method,
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typically, sshfs. For example, start 2 guest os. The one's pid is 8888
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and the other's is 9999.
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#mkdir ~/guestmount; cd ~/guestmount
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#sshfs -o allow_other,direct_io -p 5551 localhost:/ 8888/
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#sshfs -o allow_other,direct_io -p 5552 localhost:/ 9999/
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#perf kvm --host --guest --guestmount=~/guestmount top
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--guestkallsyms=<path>::
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Guest os /proc/kallsyms file copy. 'perf' kvm' reads it to get guest
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kernel symbols. Users copy it out from guest os.
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--guestmodules=<path>::
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Guest os /proc/modules file copy. 'perf' kvm' reads it to get guest
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kernel module information. Users copy it out from guest os.
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--guestvmlinux=<path>::
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Guest os kernel vmlinux.
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-v::
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--verbose::
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Be more verbose (show counter open errors, etc).
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STAT REPORT OPTIONS
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-------------------
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--vcpu=<value>::
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analyze events which occur on this vcpu. (default: all vcpus)
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--event=<value>::
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event to be analyzed. Possible values: vmexit, mmio (x86 only),
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ioport (x86 only). (default: vmexit)
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-k::
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--key=<value>::
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Sorting key. Possible values: sample (default, sort by samples
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number), time (sort by average time).
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-p::
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--pid=::
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Analyze events only for given process ID(s) (comma separated list).
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STAT LIVE OPTIONS
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-----------------
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-d::
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--display::
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Time in seconds between display updates
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-m::
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--mmap-pages=::
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Number of mmap data pages (must be a power of two) or size
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specification with appended unit character - B/K/M/G. The
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size is rounded up to have nearest pages power of two value.
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-a::
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--all-cpus::
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System-wide collection from all CPUs.
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-p::
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--pid=::
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Analyze events only for given process ID(s) (comma separated list).
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--vcpu=<value>::
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analyze events which occur on this vcpu. (default: all vcpus)
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--event=<value>::
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event to be analyzed. Possible values: vmexit,
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mmio (x86 only), ioport (x86 only).
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(default: vmexit)
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-k::
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--key=<value>::
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Sorting key. Possible values: sample (default, sort by samples
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number), time (sort by average time).
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--duration=<value>::
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Show events other than HLT (x86 only) or Wait state (s390 only)
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that take longer than duration usecs.
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--proc-map-timeout::
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When processing pre-existing threads /proc/XXX/mmap, it may take
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a long time, because the file may be huge. A time out is needed
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in such cases.
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This option sets the time out limit. The default value is 500 ms.
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SEE ALSO
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--------
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linkperf:perf-top[1], linkperf:perf-record[1], linkperf:perf-report[1],
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linkperf:perf-diff[1], linkperf:perf-buildid-list[1],
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linkperf:perf-stat[1]
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