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linux-next/tools/perf/Documentation
Alexey Budankov 504c1ad116 perf record: Implement -z,--compression_level[=<n>] option
Implemented -z,--compression_level[=<n>] option that enables compression
of mmaped kernel data buffers content in runtime during perf record mode
collection. Default option value is 1 (fastest compression).

Compression overhead has been measured for serial and AIO streaming when
profiling matrix multiplication workload:

      -------------------------------------------------------------
      | SERIAL			  | AIO-1                       |
  ----------------------------------------------------------------|
  |-z | OVH(x) | ratio(x) size(MiB) | OVH(x) | ratio(x) size(MiB) |
  |---------------------------------------------------------------|
  | 0 | 1,00   | 1,000    179,424   | 1,00   | 1,000    187,527   |
  | 1 | 1,04   | 8,427    181,148   | 1,01   | 8,474    188,562   |
  | 2 | 1,07   | 8,055    186,953   | 1,03   | 7,912    191,773   |
  | 3 | 1,04   | 8,283    181,908   | 1,03   | 8,220    191,078   |
  | 5 | 1,09   | 8,101    187,705   | 1,05   | 7,780    190,065   |
  | 8 | 1,05   | 9,217    179,191   | 1,12   | 6,111    193,024   |
  -----------------------------------------------------------------

OVH = (Execution time with -z N) / (Execution time with -z 0)

ratio - compression ratio
size  - number of bytes that was compressed

	size ~= trace size x ratio

Committer notes:

Testing it I noticed that it failed to disable build id processing when
compression is enabled, and as we'd have to uncompress everything to
look for the PERF_RECORD_{MMAP,SAMPLE,etc} to figure out which build ids
to read from DSOs, we better disable build id processing when
compression is enabled, logging with pr_debug() when doing so:

Original patch:

  # perf record -z2
  ^C[ perf record: Woken up 1 times to write data ]
  0x1746e0 [0x76]: failed to process type: 81 [Invalid argument]
  [ perf record: Captured and wrote 1.568 MB perf.data, compressed (original 0.452 MB, ratio is 3.995) ]
  #

After auto-disabling build id processing when compression is enabled:

  $ perf record -z2 sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data, compressed (original 0.001 MB, ratio is 2.292) ]
  $ perf record -v -z2 sleep 1
  Compression enabled, disabling build id collection at the end of the session.
  <SNIP extra -v pr_debug() messages>
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data, compressed (original 0.001 MB, ratio is 2.305) ]
  $

Also, with parts of the patch originally after this one moved to just
before this one we get:

  $ perf record -z2 sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data, compressed (original 0.001 MB, ratio is 2.371) ]
  $ perf report -D | grep COMPRESS
  0 0x1b8 [0x155]: PERF_RECORD_COMPRESSED: unhandled!
  0 0x30d [0x80]: PERF_RECORD_COMPRESSED: unhandled!
        COMPRESSED events:          2
        COMPRESSED events:          0
  $

I.e. when faced with PERF_RECORD_COMPRESSED that we still have no code
to process, we just show it as not being handled, skip them and
continue, while before we had:

  $ perf report -D | grep COMPRESS
  0x1b8 [0x169]: failed to process type: 81 [Invalid argument]
  Error:
  failed to process sample
  0 0x1b8 [0x169]: PERF_RECORD_COMPRESSED
  $

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/9ff06518-ae63-a908-e44d-5d9e56dd66d9@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-05-15 16:36:49 -03:00
..
android.txt perf tools: Update android build documentation 2016-07-04 20:27:27 -03:00
asciidoc.conf
asciidoctor-extensions.rb perf Documentation: Support for asciidoctor 2018-04-26 13:47:10 -03:00
build-xed.txt perf script: Add --insn-trace for instruction decoding 2018-10-24 15:29:50 -03:00
Build.txt perf tools: Add doc about how to build perf with Asan and UBSan 2019-03-19 16:52:04 -03:00
callchain-overhead-calculation.txt perf tools: Document --children option in more detail 2015-04-29 10:38:06 -03:00
examples.txt perf record: Remove -f/--force option 2013-07-08 17:37:25 -03:00
intel-bts.txt perf tools: Add Intel BTS support 2015-08-21 11:34:10 -03:00
intel-pt.txt perf scripts python: call-graph-from-sql.py: Rename to exported-sql-viewer.py 2018-10-23 14:26:44 -03:00
itrace.txt perf script: Make itrace script default to all calls 2018-10-24 15:29:54 -03:00
jit-interface.txt perf symbols: Add description of JIT interface 2012-08-13 14:55:02 -03:00
jitdump-specification.txt perf jit: Add jitdump format specification document 2016-10-24 11:07:41 -03:00
Makefile perf Documentation: Fix out-of-tree asciidoctor man page generation 2018-09-18 10:17:16 -03:00
manpage-1.72.xsl
manpage-base.xsl
manpage-bold-literal.xsl
manpage-normal.xsl
manpage-suppress-sp.xsl
perf-annotate.txt perf annotate: Add --percent-type option 2018-08-08 15:55:53 -03:00
perf-archive.txt perf archive: Remove duplicated 'runs' in man page 2013-12-09 15:21:45 -03:00
perf-bench.txt perf bench: Add epoll_ctl(2) benchmark 2018-11-21 22:39:55 -03:00
perf-buildid-cache.txt perf buildid-cache: Support --purge-all option 2018-04-26 09:30:26 -03:00
perf-buildid-list.txt perf report: Accept fifos as input file 2011-12-23 17:01:03 -02:00
perf-c2c.txt perf mem/c2c: Fix perf_mem_events to support powerpc 2019-02-04 11:32:14 -03:00
perf-config.txt perf config: Fix an error in the config template documentation 2019-03-19 16:52:04 -03:00
perf-data.txt perf tools: Correct title markers for asciidoctor 2018-03-07 10:26:32 -03:00
perf-diff.txt perf diff: Support --pid/--tid filter options 2019-03-06 18:06:16 -03:00
perf-evlist.txt perf evlist: Document missing --force option 2017-11-16 14:50:07 -03:00
perf-ftrace.txt perf tools: Correct title markers for asciidoctor 2018-03-07 10:26:32 -03:00
perf-help.txt
perf-inject.txt perf inject: Document missing options 2017-11-16 14:50:05 -03:00
perf-kallsyms.txt perf tools: Correct title markers for asciidoctor 2018-03-07 10:26:32 -03:00
perf-kmem.txt perf kmem: Document a missing option & an argument 2018-02-16 14:55:42 -03:00
perf-kvm.txt perf tools: Configurable per thread proc map processing time out 2015-06-19 18:27:13 -03:00
perf-list.txt perf tools Documentation: Fix diverse typos 2018-12-17 14:56:36 -03:00
perf-lock.txt perf lock: Document missing options 2017-11-16 14:50:04 -03:00
perf-mem.txt perf mem/c2c: Fix perf_mem_events to support powerpc 2019-02-04 11:32:14 -03:00
perf-probe.txt perf probe: Support escaped character in parser 2017-12-27 12:15:55 -03:00
perf-record.txt perf record: Implement -z,--compression_level[=<n>] option 2019-05-15 16:36:49 -03:00
perf-report.txt perf report: Implement browsing of individual samples 2019-03-11 16:33:19 -03:00
perf-sched.txt perf sched: Fix documentation for timehist 2018-04-12 10:33:36 -03:00
perf-script-perl.txt perf tools: Correct title markers for asciidoctor 2018-03-07 10:26:32 -03:00
perf-script-python.txt perf script python: Add dict fields introduction to Documentation 2018-06-06 15:40:10 -03:00
perf-script.txt perf script: Support relative time 2019-03-19 16:52:03 -03:00
perf-stat.txt perf stat: Fix --no-scale 2019-03-19 16:52:03 -03:00
perf-test.txt perf test: Add -F/--dont-fork option 2016-06-30 18:27:45 -03:00
perf-timechart.txt perf timechart: Document missing --force option 2017-11-16 14:50:06 -03:00
perf-top.txt perf top: Allow passing a kallsyms file 2018-12-17 14:54:40 -03:00
perf-trace.txt perf trace: Allow dumping a BPF map after setting up BPF events 2019-02-19 16:35:45 -03:00
perf-version.txt perf version: Add man page 2018-04-02 13:52:23 -03:00
perf.data-file-format.txt perf record: Implement COMPRESSED event record and its attributes 2019-05-15 16:36:49 -03:00
perf.txt perf tools: Handle -h and -v options 2015-10-05 16:36:18 -03:00
perfconfig.example perf config: Show default report configuration in example and docs 2016-09-01 09:44:13 -03:00
tips.txt perf tools: Add some new tips describing the new options 2019-03-11 16:33:19 -03:00