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Date: Wed, 6 Jul 2022 14:27:08 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Raul Silvera <rsilvera@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
linux-perf-users <linux-perf-users@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf inject: Add a command line option to specify build ids.
Hi Raul,
On Wed, Jun 29, 2022 at 5:18 PM Raul Silvera <rsilvera@...gle.com> wrote:
>
> This commit adds the option --known-build-ids to perf inject.
> It allows the user to explicitly specify the build id for a given
> path, instead of retrieving it from the current system. This is
> useful in cases where a perf.data file is processed on a different
> system from where it was collected, or if some of the binaries are
> no longer available.
>
> The build ids and paths are specified in pairs in the command line.
> Using the file:// specifier, build ids can be loaded from a file
> directly generated by perf buildid-list. This is convenient to copy
> build ids from one perf.data file to another.
>
> ** Example: In this example we use perf record to create two
> perf.data files, one with build ids and another without, and use
> perf buildid-list and perf inject to copy the build ids from the
> first file to the second.
>
> $ perf record ls /tmp # Create perf.data file
> $ perf record --no-buildid ls /tmp -o perf.data.no-buildid
> $ perf buildid-list > /tmp/build-ids.txt
> $ perf inject -b --known-build-ids='file:///tmp/build-ids.txt' \
> $ -i perf.data.no-buildid -o perf.data.buildid
You'd better indent the block for the readability and to prevent
possible interference from the shell (for comments usually).
The last line is a continuation from the above line and it used
to print other prompts like ">".
>
> Signed-off-by: Raul Silvera <rsilvera@...gle.com>
> ---
> tools/perf/builtin-inject.c | 57 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index a75bf11585b5..667b942f870e 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -21,6 +21,7 @@
> #include "util/data.h"
> #include "util/auxtrace.h"
> #include "util/jit.h"
> +#include "util/string2.h"
> #include "util/symbol.h"
> #include "util/synthetic-events.h"
> #include "util/thread.h"
> @@ -35,6 +36,7 @@
>
> #include <linux/list.h>
> #include <linux/string.h>
> +#include <ctype.h>
> #include <errno.h>
> #include <signal.h>
>
> @@ -59,6 +61,8 @@ struct perf_inject {
> struct itrace_synth_opts itrace_synth_opts;
> char event_copy[PERF_SAMPLE_MAX_SIZE];
> struct perf_file_section secs[HEADER_FEAT_BITS];
> + const char *known_build_ids_source;
> + struct strlist *known_build_ids;
> };
>
> struct event_entry {
> @@ -570,9 +574,43 @@ static int dso__read_build_id(struct dso *dso)
> return dso->has_build_id ? 0 : -1;
> }
>
> +static bool perf_inject__lookup_known_build_id(struct perf_inject *inject,
> + struct dso *dso)
> +{
> + struct str_node *pos;
> + int bid_len;
> +
> + strlist__for_each_entry(pos, inject->known_build_ids) {
> + const char *space;
> +
> + pos->s = skip_spaces(pos->s);
> + space = strstr(pos->s, " ");
> + if (space == NULL ||
> + !strcmp(dso->long_name, skip_spaces(space)))
> + continue;
> + bid_len = space - pos->s;
> + if (bid_len == 0 || bid_len / 2 > BUILD_ID_SIZE)
I'm not sure how bid_len can be 0. And you can compare to
SBUILD_ID_SIZE (without dividing by 2) - but it'd be ">=".
Also it could be worthwhile to check if bid_len is even.
> + return false;
> + for (int ix = 0; 2 * ix + 1 < bid_len; ++ix) {
> + if (!isxdigit(pos->s[2 * ix]) ||
> + !isxdigit(pos->s[2 * ix + 1]))
> + return false;
> +
> + dso->bid.data[ix] = (hex(pos->s[2 * ix]) << 4 |
> + hex(pos->s[2 * ix + 1]));
> + }
> + dso->bid.size = bid_len / 2;
> + dso->has_build_id = 1;
> + return true;
> + }
> + return false;
> +}
> +
> static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
> struct machine *machine, u8 cpumode, u32 flags)
> {
> + struct perf_inject *inject = container_of(tool, struct perf_inject,
> + tool);
> int err;
>
> if (is_anon_memory(dso->long_name) || flags & MAP_HUGETLB)
> @@ -580,6 +618,10 @@ static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
> if (is_no_dso_memory(dso->long_name))
> return 0;
>
> + if (inject->known_build_ids != NULL &&
> + perf_inject__lookup_known_build_id(inject, dso))
> + return 1;
> +
> if (dso__read_build_id(dso) < 0) {
> pr_debug("no build_id found for %s\n", dso->long_name);
> return -1;
> @@ -1082,6 +1124,9 @@ int cmd_inject(int argc, const char **argv)
> "Inject build-ids into the output stream"),
> OPT_BOOLEAN(0, "buildid-all", &inject.build_id_all,
> "Inject build-ids of all DSOs into the output stream"),
> + OPT_STRING(0, "known-build-ids", &inject.known_build_ids_source,
> + "buildid path [buildid path...]",
> + "build-ids to use for specific files"),
> OPT_STRING('i', "input", &inject.input_name, "file",
> "input file name"),
> OPT_STRING('o', "output", &inject.output.path, "file",
> @@ -1215,6 +1260,18 @@ int cmd_inject(int argc, const char **argv)
> */
> inject.tool.ordered_events = true;
> inject.tool.ordering_requires_timestamps = true;
> + if (inject.known_build_ids_source != NULL) {
> + struct strlist *known_build_ids;
> +
> + known_build_ids = strlist__new(
> + inject.known_build_ids_source, NULL);
> +
> + if (known_build_ids == NULL) {
> + pr_err("Couldn't parse known build ids.\n");
> + goto out_delete;
> + }
> + inject.known_build_ids = known_build_ids;
You need to release it after use. Note that strlist__delete()
accepts a NULL pointer.
Thanks,
Namhyung
> + }
> }
>
> if (inject.sched_stat) {
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>
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