Re: [PATCH 24/24] perf record: Add --buildid-mmap option to enable mmap's build id
From: Namhyung Kim
Date: Thu Nov 12 2020 - 23:40:32 EST
On Mon, Nov 09, 2020 at 10:54:15PM +0100, Jiri Olsa wrote:
> Adding --buildid-mmap option to enable build id in mmap2 events.
> It will only work if there's kernel support for that and it disables
> build id cache (implies --no-buildid).
>
> It's also possible to enable it permanently via config option
> in ~.perfconfig file:
>
> [record]
> build-id=mmap
You also need to update the documentation.
>
> Also added build_id bit in the verbose output for perf_event_attr:
>
> # perf record --buildid-mmap -vv
> ...
> perf_event_attr:
> type 1
> size 120
> ...
> build_id 1
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> tools/perf/Documentation/perf-record.txt | 3 +++
> tools/perf/builtin-record.c | 20 ++++++++++++++++++++
> tools/perf/util/evsel.c | 10 ++++++----
> tools/perf/util/perf_api_probe.c | 10 ++++++++++
> tools/perf/util/perf_api_probe.h | 1 +
> tools/perf/util/perf_event_attr_fprintf.c | 1 +
> tools/perf/util/record.h | 1 +
> 7 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index 768888b9326a..1bcf51e24979 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -482,6 +482,9 @@ Specify vmlinux path which has debuginfo.
> --buildid-all::
> Record build-id of all DSOs regardless whether it's actually hit or not.
>
> +--buildid-mmap::
> +Record build ids in mmap2 events, disables build id cache (implies --no-buildid).
> +
> --aio[=n]::
> Use <n> control blocks in asynchronous (Posix AIO) trace writing mode (default: 1, max: 4).
> Asynchronous mode is supported only when linking Perf tool with libc library
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index adf311d15d3d..47bae9d82d43 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -102,6 +102,7 @@ struct record {
> bool no_buildid_cache;
> bool no_buildid_cache_set;
> bool buildid_all;
> + bool buildid_mmap;
> bool timestamp_filename;
> bool timestamp_boundary;
> struct switch_output switch_output;
> @@ -2139,6 +2140,8 @@ static int perf_record_config(const char *var, const char *value, void *cb)
> rec->no_buildid_cache = true;
> else if (!strcmp(value, "skip"))
> rec->no_buildid = true;
> + else if (!strcmp(value, "mmap"))
> + rec->buildid_mmap = true;
> else
> return -1;
> return 0;
> @@ -2554,6 +2557,8 @@ static struct option __record_options[] = {
> "file", "vmlinux pathname"),
> OPT_BOOLEAN(0, "buildid-all", &record.buildid_all,
> "Record build-id of all DSOs regardless of hits"),
> + OPT_BOOLEAN(0, "buildid-mmap", &record.buildid_mmap,
> + "Record build-id in map events"),
> OPT_BOOLEAN(0, "timestamp-filename", &record.timestamp_filename,
> "append timestamp to output filename"),
> OPT_BOOLEAN(0, "timestamp-boundary", &record.timestamp_boundary,
> @@ -2657,6 +2662,21 @@ int cmd_record(int argc, const char **argv)
>
> }
>
> + if (rec->buildid_mmap) {
> + if (!perf_can_record_build_id()) {
> + pr_err("Failed: no support to record build id in mmap events, update your kernel.\n");
> + err = -EINVAL;
> + goto out_opts;
> + }
> + pr_debug("Enabling build id in mmap2 events.\n");
> + /* Enable mmap build id synthesizing. */
> + symbol_conf.buildid_mmap2 = true;
> + /* Enable perf_event_attr::build_id bit. */
> + rec->opts.build_id = true;
> + /* Disable build id cache. */
> + rec->no_buildid = true;
I'm afraid this can make it miss some build-id in the end because of
the possibility of the failure.
> + }
> +
> if (rec->opts.kcore)
> rec->data.is_dir = true;
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 1cad6051d8b0..749d806ee1d1 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1170,10 +1170,12 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
> if (opts->sample_weight)
> evsel__set_sample_bit(evsel, WEIGHT);
>
> - attr->task = track;
> - attr->mmap = track;
> - attr->mmap2 = track && !perf_missing_features.mmap2;
> - attr->comm = track;
> + attr->task = track;
> + attr->mmap = track;
> + attr->mmap2 = track && !perf_missing_features.mmap2;
> + attr->comm = track;
> + attr->build_id = track && opts->build_id;
> +
> /*
> * ksymbol is tracked separately with text poke because it needs to be
> * system wide and enabled immediately.
> diff --git a/tools/perf/util/perf_api_probe.c b/tools/perf/util/perf_api_probe.c
> index 3840d02f0f7b..829af17a0867 100644
> --- a/tools/perf/util/perf_api_probe.c
> +++ b/tools/perf/util/perf_api_probe.c
> @@ -98,6 +98,11 @@ static void perf_probe_text_poke(struct evsel *evsel)
> evsel->core.attr.text_poke = 1;
> }
>
> +static void perf_probe_build_id(struct evsel *evsel)
> +{
> + evsel->core.attr.build_id = 1;
> +}
> +
> bool perf_can_sample_identifier(void)
> {
> return perf_probe_api(perf_probe_sample_identifier);
> @@ -172,3 +177,8 @@ bool perf_can_aux_sample(void)
>
> return true;
> }
> +
> +bool perf_can_record_build_id(void)
> +{
> + return perf_probe_api(perf_probe_build_id);
> +}
> diff --git a/tools/perf/util/perf_api_probe.h b/tools/perf/util/perf_api_probe.h
> index d5506a983a94..f12ca55f509a 100644
> --- a/tools/perf/util/perf_api_probe.h
> +++ b/tools/perf/util/perf_api_probe.h
> @@ -11,5 +11,6 @@ bool perf_can_record_cpu_wide(void);
> bool perf_can_record_switch_events(void);
> bool perf_can_record_text_poke_events(void);
> bool perf_can_sample_identifier(void);
> +bool perf_can_record_build_id(void);
>
> #endif // __PERF_API_PROBE_H
> diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
> index e67a227c0ce7..0f1c62d40a89 100644
> --- a/tools/perf/util/perf_event_attr_fprintf.c
> +++ b/tools/perf/util/perf_event_attr_fprintf.c
> @@ -134,6 +134,7 @@ int perf_event_attr__fprintf(FILE *fp, struct perf_event_attr *attr,
> PRINT_ATTRf(bpf_event, p_unsigned);
> PRINT_ATTRf(aux_output, p_unsigned);
> PRINT_ATTRf(cgroup, p_unsigned);
> + PRINT_ATTRf(build_id, p_unsigned);
You might want to add the missing text_poke bit too. :)
Thanks,
Namhyung
>
> PRINT_ATTRn("{ wakeup_events, wakeup_watermark }", wakeup_events, p_unsigned);
> PRINT_ATTRf(bp_type, p_unsigned);
> diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
> index 266760ac9143..609e706f4282 100644
> --- a/tools/perf/util/record.h
> +++ b/tools/perf/util/record.h
> @@ -49,6 +49,7 @@ struct record_opts {
> bool no_bpf_event;
> bool kcore;
> bool text_poke;
> + bool build_id;
> unsigned int freq;
> unsigned int mmap_pages;
> unsigned int auxtrace_mmap_pages;
> --
> 2.26.2
>