Commit 14d3d540 authored May 07, 2020 by Jiri Olsa Committed by Arnaldo Carvalho de Melo May 28, 2020

perf session: Try to read pipe data from file



Ian came with the idea of having support to read the pipe data also from
file. Currently pipe mode files fail like:

  $ perf record -o - sleep 1 > /tmp/perf.pipe.data
  $ perf report -i /tmp/perf.pipe.data
  incompatible file format (rerun with -v to learn more)

This patch adds the support to do that by trying the pipe header first,
and if its successfully detected, switching the perf data to pipe mode.

Committer testing:

  # ls
  # perf record -a -o - sleep 1 > /tmp/perf.pipe.data
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  # ls
  # perf report -i /tmp/perf.pipe.data | head -25
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 511  of event 'cycles'
  # Event count (approx.): 178447276
  #
  # Overhead  Command   Shared Object      Symbol
  # ........  ........  .................  ...........................................................................................
  #
      65.49%  swapper   [kernel.kallsyms]  [k] native_safe_halt
       6.45%  chromium  libblink_core.so   [.] blink::SelectorChecker::CheckOne
       4.08%  chromium  libblink_core.so   [.] blink::SelectorQuery::ExecuteForTraverseRoot<blink::AllElementsSelectorQueryTrait>
       2.25%  chromium  libblink_core.so   [.] blink::SelectorQuery::FindTraverseRootsAndExecute<blink::AllElementsSelectorQueryTrait>
       2.11%  chromium  libblink_core.so   [.] blink::SelectorChecker::MatchSelector
       1.91%  chromium  libblink_core.so   [.] blink::Node::OwnerShadowHost
       1.31%  chromium  libblink_core.so   [.] blink::Node::parentNode@plt
       1.22%  chromium  libblink_core.so   [.] blink::Node::parentNode
       0.59%  chromium  libblink_core.so   [.] blink::AnyAttributeMatches
       0.58%  chromium  libv8.so           [.] v8::internal::GlobalHandles::Create
       0.58%  chromium  libblink_core.so   [.] blink::NodeTraversal::NextAncestorSibling
       0.55%  chromium  libv8.so           [.] v8::internal::RegExpGlobalCache::RegExpGlobalCache
       0.55%  chromium  libblink_core.so   [.] blink::Node::ContainingShadowRoot
       0.55%  chromium  libblink_core.so   [.] blink::NodeTraversal::NextAncestorSibling@plt
  #

Original-patch-by: Ian Rogers <irogers@google.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Khuong <pvk@pvk.ca>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200507095024.2789147-4-jolsa@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent b491198d

tools/perf/util/header.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -3574,7 +3574,7 @@ static int perf_header__read_pipe(struct perf_session *session)
		return -EINVAL;
		}

		return 0;
		return f_header.size == sizeof(f_header) ? 0 : -1;
		}

		static int read_attr(int fd, struct perf_header *ph,
		@@ -3676,7 +3676,7 @@ int perf_session__read_header(struct perf_session *session)
		struct perf_file_header f_header;
		struct perf_file_attr f_attr;
		u64 f_id;
		int nr_attrs, nr_ids, i, j;
		int nr_attrs, nr_ids, i, j, err;
		int fd = perf_data__fd(data);

		session->evlist = evlist__new();
		@@ -3685,8 +3685,16 @@ int perf_session__read_header(struct perf_session *session)

		session->evlist->env = &header->env;
		session->machines.host.env = &header->env;
		if (perf_data__is_pipe(data))
		return perf_header__read_pipe(session);

		/*
		* We can read 'pipe' data event from regular file,
		* check for the pipe header regardless of source.
		*/
		err = perf_header__read_pipe(session);
		if (!err \|\| (err && perf_data__is_pipe(data))) {
		data->is_pipe = true;
		return err;
		}

		if (perf_file_header__read(&f_header, header, fd) < 0)
		return -EINVAL;

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