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>

1 files changed, 30 insertions, 0 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index a0bd9104fae6..861395753c25 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -443,6 +443,25 @@ static int record__mmap_flush_parse(const struct option *opt,
 	return 0;
 }
 
+#ifdef HAVE_ZSTD_SUPPORT
+static unsigned int comp_level_default = 1;
+
+static int record__parse_comp_level(const struct option *opt, const char *str, int unset)
+{
+	struct record_opts *opts = opt->value;
+
+	if (unset) {
+		opts->comp_level = 0;
+	} else {
+		if (str)
+			opts->comp_level = strtol(str, NULL, 0);
+		if (!opts->comp_level)
+			opts->comp_level = comp_level_default;
+	}
+
+	return 0;
+}
+#endif
 static unsigned int comp_level_max = 22;
 
 static int record__comp_enabled(struct record *rec)
@@ -2200,6 +2219,11 @@ static struct option __record_options[] = {
 	OPT_CALLBACK(0, "affinity", &record.opts, "node|cpu",
 		     "Set affinity mask of trace reading thread to NUMA node cpu mask or cpu of processed mmap buffer",
 		     record__parse_affinity),
+#ifdef HAVE_ZSTD_SUPPORT
+	OPT_CALLBACK_OPTARG('z', "compression-level", &record.opts, &comp_level_default,
+			    "n", "Compressed records using specified level (default: 1 - fastest compression, 22 - greatest compression)",
+			    record__parse_comp_level),
+#endif
 	OPT_END()
 };
 
@@ -2259,6 +2283,12 @@ int cmd_record(int argc, const char **argv)
 			"cgroup monitoring only available in system-wide mode");
 
 	}
+
+	if (rec->opts.comp_level != 0) {
+		pr_debug("Compression enabled, disabling build id collection at the end of the session.\n");
+		rec->no_buildid = true;
+	}
+
 	if (rec->opts.record_switch_events &&
 	    !perf_can_record_switch_events()) {
 		ui__error("kernel does not support recording context switch events\n");