linux-stable/tools/perf/Documentation/perf-inject.txt
Stephane Eranian 9b07e27f88 perf inject: Add jitdump mmap injection support
This patch adds a --jit/-j option to perf inject.

This options injects MMAP records into the perf.data file to cover the
jitted code mmaps. It also emits ELF images for each function in the
jidump file.  Those images are created where the jitdump file is.  The
MMAP records point to that location as well.

Typical flow:

  $ perf record -k mono -- java -agentpath:libpjvmti.so java_class
  $ perf inject --jit -i perf.data -o perf.data.jitted
  $ perf report -i perf.data.jitted

Note that jitdump.h support is not limited to Java, it works with any
jitted environment modified to emit the jitdump file format, include
those where code can be jitted multiple times and moved around.

The jitdump.h format is adapted from the Oprofile project.

The genelf.c (ELF binary generation) depends on MD5 hash encoding for
the buildid. To enable this, libssl-dev must be installed. If not, then
genelf.c defaults to using urandom to generate the buildid, which is not
ideal.  The Makefile auto-detects the presence on libssl-dev.

This version mmaps the jitdump file to create a marker MMAP record in
the perf.data file. The marker is used to detect jitdump and cause perf
inject to inject the jitted mmaps and generate ELF images for jitted
functions.

In V8, the following fixes and changes were made among other things:

  -  the jidump header format include a new flags field to be used
     to carry information about the configuration of the runtime agent.
     Contributed by: Adrian Hunter <adrian.hunter@intel.com>

  - Fix mmap pgoff: MMAP event pgoff must be the offset within the ELF file
    at which the code resides.
    Contributed by: Adrian Hunter <adrian.hunter@intel.com>

  - Fix ELF virtual addresses: perf tools expect the ELF virtual addresses of dynamic
    objects to match the file offset.
    Contributed by: Adrian Hunter <adrian.hunter@intel.com>

  - JIT MMAP injection does not obey finished_round semantics. JIT MMAP injection injects all
    MMAP events in one go, so it does not obey finished_round semantics, so drop the
    finished_round events from the output perf.data file.
    Contributed by: Adrian Hunter <adrian.hunter@intel.com>

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Carl Love <cel@us.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John McCutchan <johnmccutchan@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sonny Rao <sonnyrao@chromium.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1448874143-7269-3-git-send-email-eranian@google.com
[ Moved inject.build_ids ordering bits to a separate patch, fixed the NO_LIBELF=1 build ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-02-05 09:46:45 -03:00

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perf-inject(1)
==============
NAME
----
perf-inject - Filter to augment the events stream with additional information
SYNOPSIS
--------
[verse]
'perf inject <options>'
DESCRIPTION
-----------
perf-inject reads a perf-record event stream and repipes it to stdout. At any
point the processing code can inject other events into the event stream - in
this case build-ids (-b option) are read and injected as needed into the event
stream.
Build-ids are just the first user of perf-inject - potentially anything that
needs userspace processing to augment the events stream with additional
information could make use of this facility.
OPTIONS
-------
-b::
--build-ids=::
Inject build-ids into the output stream
-v::
--verbose::
Be more verbose.
-i::
--input=::
Input file name. (default: stdin)
-o::
--output=::
Output file name. (default: stdout)
-s::
--sched-stat::
Merge sched_stat and sched_switch for getting events where and how long
tasks slept. sched_switch contains a callchain where a task slept and
sched_stat contains a timeslice how long a task slept.
--kallsyms=<file>::
kallsyms pathname
--itrace::
Decode Instruction Tracing data, replacing it with synthesized events.
Options are:
include::itrace.txt[]
--strip::
Use with --itrace to strip out non-synthesized events.
-j::
--jit::
Process jitdump files by injecting the mmap records corresponding to jitted
functions. This option also generates the ELF images for each jitted function
found in the jitdumps files captured in the input perf.data file. Use this option
if you are monitoring environment using JIT runtimes, such as Java, DART or V8.
SEE ALSO
--------
linkperf:perf-record[1], linkperf:perf-report[1], linkperf:perf-archive[1]