Commit 00dc8657 authored Nov 04, 2014 by Namhyung Kim Committed by Arnaldo Carvalho de Melo Nov 05, 2014

perf record: Do not save pathname in ./debug/.build-id directory for vmlinux



When perf record finishes a session, it pre-processes samples in order
to write build-id info from DSOs that had samples.

During this process it'll call map__load() for the kernel map, and it
ends up calling dso__load_vmlinux_path() which replaces dso->long_name.

But this function checks kernel's build-id before searching vmlinux path
so it'll end up with a cryptic name, the pathname for the entry in the
~/.debug cache, which can be confusing to users.

This patch adds a flag to skip the build-id check during record, so
that it'll have the original vmlinux path for the kernel dso->long_name,
not the entry in the ~/.debug cache.

Before:
  # perf record -va sleep 3
  mmap size 528384B
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.196 MB perf.data (~8545 samples) ]
  Looking at the vmlinux_path (7 entries long)
  Using /home/namhyung/.debug/.build-id/f0/6e17aa50adf4d00b88925e03775de107611551 for symbols

After:
  # perf record -va sleep 3
  mmap size 528384B
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.193 MB perf.data (~8432 samples) ]
  Looking at the vmlinux_path (7 entries long)
  Using /lib/modules/3.16.4-1-ARCH/build/vmlinux for symbols

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1415063674-17206-7-git-send-email-namhyung@kernel.org


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

parent e195fac8

tools/perf/builtin-record.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -200,6 +200,17 @@ static int process_buildids(struct record *rec)
		if (size == 0)
		return 0;

		/*
		* During this process, it'll load kernel map and replace the
		* dso->long_name to a real pathname it found. In this case
		* we prefer the vmlinux path like
		* /lib/modules/3.16.4/build/vmlinux
		*
		* rather than build-id path (in debug directory).
		* $HOME/.debug/.build-id/f0/6e17aa50adf4d00b88925e03775de107611551
		*/
		symbol_conf.ignore_vmlinux_buildid = true;

		return __perf_session__process_events(session, start,
		size - start,
		size, &build_id__mark_dso_hit_ops);

tools/perf/util/symbol.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -1511,11 +1511,9 @@ int dso__load_vmlinux_path(struct dso dso, struct map map,
		symbol_filter_t filter)
		{
		int i, err = 0;
		char *filename;

		pr_debug("Looking at the vmlinux_path (%d entries long)\n",
		vmlinux_path__nr_entries + 1);
		char *filename = NULL;

		if (!symbol_conf.ignore_vmlinux_buildid)
		filename = dso__build_id_filename(dso, NULL, 0);
		if (filename != NULL) {
		err = dso__load_vmlinux(dso, map, filename, true, filter);
		@@ -1524,6 +1522,9 @@ int dso__load_vmlinux_path(struct dso dso, struct map map,
		free(filename);
		}

		pr_debug("Looking at the vmlinux_path (%d entries long)\n",
		vmlinux_path__nr_entries + 1);

		for (i = 0; i < vmlinux_path__nr_entries; ++i) {
		err = dso__load_vmlinux(dso, map, vmlinux_path[i], false, filter);
		if (err > 0)

tools/perf/util/symbol.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -105,6 +105,7 @@ struct symbol_conf {
		unsigned short nr_events;
		bool try_vmlinux_path,
		ignore_vmlinux,
		ignore_vmlinux_buildid,
		show_kernel_path,
		use_modules,
		sort_by_name,