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perf record: Implement -z,--compression_level[=<n>] option

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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>
This commit is contained in:
Alexey Budankov
2019-03-18 20:44:42 +03:00
committed by Arnaldo Carvalho de Melo
parent 61a7773ca8
commit 504c1ad116
2 changed files with 35 additions and 0 deletions
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5
tools/perf/Documentation/perf-record.txt
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@@ -478,6 +478,11 @@ Also at some cases executing less output write syscalls with bigger data size
can take less time than executing more output write syscalls with smaller data
size thus lowering runtime profiling overhead.
-z::
--compression-level[=n]::
Produce compressed trace using specified level n (default: 1 - fastest compression,
22 - smallest trace)
--all-kernel::
Configure all used events to run in kernel space.