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92ea788d2a
There are applications not built with frame pointers, so DWARF is needed
to get the stack traces.
`perf record --call-graph dwarf` saves the stack and register data for
each sample to get the stacktrace offline. But sometimes this data may
have sensitive information and we don't want to keep them in the file.
This new 'perf inject --convert-callchain' option creates the callchains
and discards the stack and register after that.
This saves storage space and processing time for the new data file.
Of course, users should remove the original data file to not keep
sensitive data around. :)
The down side is that it cannot handle inlined callchain entries as they
all have the same IPs.
Maybe we can add an option to 'perf report' to look up inlined functions
using DWARF - IIUC it doesn't require stack and register data.
This is an example.
$ perf record --call-graph dwarf -- perf test -w noploop
$ perf report --stdio --no-children --percent-limit=0 > output-prev
$ perf inject -i perf.data --convert-callchain -o perf.data.out
$ perf report --stdio --no-children --percent-limit=0 -i perf.data.out > output-next
$ diff -u output-prev output-next
...
0.23% perf ld-linux-x86-64.so.2 [.] _dl_relocate_object_no_relro
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- ---elf_dynamic_do_Rela (inlined)
- _dl_relocate_object_no_relro
+ ---_dl_relocate_object_no_relro
_dl_relocate_object
dl_main
_dl_sysdep_start
- _dl_start_final (inlined)
_dl_start
_start
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
124 lines
4 KiB
Text
124 lines
4 KiB
Text
perf-inject(1)
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==============
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NAME
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----
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perf-inject - Filter to augment the events stream with additional information
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SYNOPSIS
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--------
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[verse]
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'perf inject <options>'
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DESCRIPTION
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-----------
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perf-inject reads a perf-record event stream and repipes it to stdout. At any
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point the processing code can inject other events into the event stream - in
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this case build-ids (-b option) are read and injected as needed into the event
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stream.
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Build-ids are just the first user of perf-inject - potentially anything that
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needs userspace processing to augment the events stream with additional
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information could make use of this facility.
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OPTIONS
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-------
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-b::
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--build-ids::
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Inject build-ids of DSOs hit by samples into the output stream.
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This means it needs to process all SAMPLE records to find the DSOs.
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--buildid-all::
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Inject build-ids of all DSOs into the output stream regardless of hits
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and skip SAMPLE processing.
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--known-build-ids=::
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Override build-ids to inject using these comma-separated pairs of
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build-id and path. Understands file://filename to read these pairs
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from a file, which can be generated with perf buildid-list.
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-v::
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--verbose::
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Be more verbose.
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-i::
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--input=::
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Input file name. (default: stdin)
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-o::
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--output=::
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Output file name. (default: stdout)
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-s::
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--sched-stat::
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Merge sched_stat and sched_switch for getting events where and how long
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tasks slept. sched_switch contains a callchain where a task slept and
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sched_stat contains a timeslice how long a task slept.
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-k::
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--vmlinux=<file>::
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vmlinux pathname
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--ignore-vmlinux::
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Ignore vmlinux files.
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--kallsyms=<file>::
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kallsyms pathname
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--itrace::
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Decode Instruction Tracing data, replacing it with synthesized events.
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Options are:
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include::itrace.txt[]
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--strip::
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Use with --itrace to strip out non-synthesized events.
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-j::
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--jit::
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Process jitdump files by injecting the mmap records corresponding to jitted
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functions. This option also generates the ELF images for each jitted function
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found in the jitdumps files captured in the input perf.data file. Use this option
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if you are monitoring environment using JIT runtimes, such as Java, DART or V8.
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-f::
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--force::
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Don't complain, do it.
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--vm-time-correlation[=OPTIONS]::
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Some architectures may capture AUX area data which contains timestamps
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affected by virtualization. This option will update those timestamps
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in place, to correlate with host timestamps. The in-place update means
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that an output file is not specified, and instead the input file is
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modified. The options are architecture specific, except that they may
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start with "dry-run" which will cause the file to be processed but
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without updating it. Currently this option is supported only by
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Intel PT, refer linkperf:perf-intel-pt[1]
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--guest-data=<path>,<pid>[,<time offset>[,<time scale>]]::
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Insert events from a perf.data file recorded in a virtual machine at
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the same time as the input perf.data file was recorded on the host.
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The Process ID (PID) of the QEMU hypervisor process must be provided,
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and the time offset and time scale (multiplier) will likely be needed
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to convert guest time stamps into host time stamps. For example, for
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x86 the TSC Offset and Multiplier could be provided for a virtual machine
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using Linux command line option no-kvmclock.
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Currently only mmap, mmap2, comm, task, context_switch, ksymbol,
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and text_poke events are inserted, as well as build ID information.
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The QEMU option -name debug-threads=on is needed so that thread names
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can be used to determine which thread is running which VCPU. Note
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libvirt seems to use this by default.
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When using perf record in the guest, option --sample-identifier
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should be used, and also --buildid-all and --switch-events may be
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useful.
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--convert-callchain::
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Parse DWARF callchains and convert them to usual callchains. This also
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discards stack and register data from the samples. This will lose
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inlined callchain entries.
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:GMEXAMPLECMD: inject
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:GMEXAMPLESUBCMD:
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include::guestmount.txt[]
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SEE ALSO
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--------
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linkperf:perf-record[1], linkperf:perf-report[1], linkperf:perf-archive[1],
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linkperf:perf-intel-pt[1]
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