Re: [PATCH v8 6/8] perf tools: Enable overwrite settings

From: Arnaldo Carvalho de Melo
Date: Tue Jun 21 2016 - 18:00:16 EST

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Em Mon, Jun 20, 2016 at 10:47:23AM +0000, Wang Nan escreveu:
> This patch allows following config terms and option:
>
> Globally setting events to overwrite;
>
> # perf record --overwrite ...
>
> Set specific events to be overwrite or no-overwrite.
>
> # perf record --event cycles/overwrite/ ...
> # perf record --event cycles/no-overwrite/ ...
>
> Add missing config terms and update config term array size because the
> longest string length is changed.
>
> For overwritable events, automatically select attr.write_backward since
> perf requires it to be backward for reading.
>
> Test result:
> # perf record --overwrite -e syscalls:*enter_nanosleep* usleep 1
> [ perf record: Woken up 2 times to write data ]
> [ perf record: Captured and wrote 0.011 MB perf.data (1 samples) ]
> # perf evlist -v
> syscalls:sys_enter_nanosleep: type: 2, size: 112, config: 0x134, { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|PERIOD|RAW, disabled: 1, inherit: 1, mmap: 1, comm: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, write_backward: 1
> # Tip: use 'perf evlist --trace-fields' to show fields for tracepoint events
>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Zefan Li <lizefan@xxxxxxxxxx>
> Cc: pi3orama@xxxxxxx
> ---
> tools/perf/Documentation/perf-record.txt | 14 ++++++++++++++
> tools/perf/builtin-record.c | 1 +
> tools/perf/perf.h | 1 +
> tools/perf/tests/backward-ring-buffer.c | 15 ++++++---------
> tools/perf/util/evsel.c | 12 ++++++++++++
> tools/perf/util/evsel.h | 2 ++
> tools/perf/util/parse-events.c | 20 ++++++++++++++++++--
> tools/perf/util/parse-events.h | 2 ++
> tools/perf/util/parse-events.l | 2 ++
> 9 files changed, 58 insertions(+), 11 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index 8dbee83..f5cb932 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -360,6 +360,20 @@ particular perf.data snapshot should be kept or not.
>
> Implies --timestamp-filename, --no-buildid and --no-buildid-cache.
>
> +--overwrite::
> +Makes all events use overwritable ring buffer. Event with overwritable ring
> +buffer works like a flight recorder: when buffer gets full, instead of dumping
> +records into output file, kernel overwrites old records silently. Perf dumps
> +data from overwritable ring buffer when switching output (see --switch-output)
> +and before terminate.

What about: (some other alternative paragraphs below)

---------------

Makes all events use an overwritable ring buffer. An overwritable ring
buffer works like a flight recorder: when it gets full, the kernel will
overwrite the oldest records, that thus will never make it to the
perf.data file.

> +
> +Perf behaves like a daemon when '--overwrite' and '--switch-output' are
> +provided. It record and drop events in background, and dumps data when
> +something unusual is detected.

When '--overwrite' and '--switch-output' are used perf records and drops
events until it receives a signal, meaning that something unusual was
detected that warrants taking a snapshot of the most current events,
those fitting in the ring buffer at that moment.

> +
> +'overwrite' attribute can also be set or canceled for specific event using
an
> +config terms like 'cycles/overwrite/' and 'instructions/no-overwrite/'.
in
> +
> SEE ALSO
> --------
> linkperf:perf-stat[1], linkperf:perf-list[1]
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 48c0051..bb62882 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1520,6 +1520,7 @@ struct option __record_options[] = {
> OPT_BOOLEAN_SET('i', "no-inherit", &record.opts.no_inherit,
> &record.opts.no_inherit_set,
> "child tasks do not inherit counters"),
> + OPT_BOOLEAN(0, "overwrite", &record.opts.overwrite, "use overwrite mode"),
> OPT_UINTEGER('F', "freq", &record.opts.user_freq, "profile at this frequency"),
> OPT_CALLBACK('m', "mmap-pages", &record.opts, "pages[,pages]",
> "number of mmap data pages and AUX area tracing mmap pages",
> diff --git a/tools/perf/perf.h b/tools/perf/perf.h
> index cd8f1b1..608b42b 100644
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -59,6 +59,7 @@ struct record_opts {
> bool record_switch_events;
> bool all_kernel;
> bool all_user;
> + bool overwrite;
> unsigned int freq;
> unsigned int mmap_pages;
> unsigned int auxtrace_mmap_pages;
> diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
> index 76e34c0..bba0b83 100644
> --- a/tools/perf/tests/backward-ring-buffer.c
> +++ b/tools/perf/tests/backward-ring-buffer.c
> @@ -130,27 +130,24 @@ int test__backward_ring_buffer(int subtest __maybe_unused)
> }
>
> bzero(&parse_error, sizeof(parse_error));
> - err = parse_events(evlist, "syscalls:sys_enter_prctl", &parse_error);
> + /*
> + * Set backward bit, ring buffer should be writing from end. Record
> + * it in aux evlist
> + */
> + err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error);
> if (err) {
> pr_debug("Failed to parse tracepoint event, try use root\n");
> ret = TEST_SKIP;
> goto out_delete_evlist;
> }
>
> - /*
> - * Set backward bit, ring buffer should be writing from end. Record
> - * it in aux evlist
> - */
> - perf_evlist__last(evlist)->overwrite = true;
> - perf_evlist__last(evlist)->attr.write_backward = 1;
> -
> + /* Don't set backward bit for exit event. Record it in main evlist */
> err = parse_events(evlist, "syscalls:sys_exit_prctl", &parse_error);
> if (err) {
> pr_debug("Failed to parse tracepoint event, try use root\n");
> ret = TEST_SKIP;
> goto out_delete_evlist;
> }
> - /* Don't set backward bit for exit event. Record it in main evlist */
>
> perf_evlist__config(evlist, &opts, NULL);
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 1d8f2bb..3629520 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -677,11 +677,22 @@ static void apply_config_terms(struct perf_evsel *evsel,
> */
> attr->inherit = term->val.inherit ? 1 : 0;
> break;
> + case PERF_EVSEL__CONFIG_TERM_OVERWRITE:
> + evsel->overwrite = term->val.overwrite ? 1 : 0;
> + break;
> default:
> break;
> }
> }
>
> + /*
> + * Set backward after config term processing because it is
> + * possible to set overwrite globally, without config
> + * terms.
> + */
> + if (evsel->overwrite)
> + attr->write_backward = 1;
> +
> /* User explicitly set per-event callgraph, clear the old setting and reset. */
> if ((callgraph_buf != NULL) || (dump_size > 0) || max_stack) {
> if (max_stack) {
> @@ -758,6 +769,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
>
> attr->sample_id_all = perf_missing_features.sample_id_all ? 0 : 1;
> attr->inherit = !opts->no_inherit;
> + evsel->overwrite = opts->overwrite;
>
> perf_evsel__set_sample_bit(evsel, IP);
> perf_evsel__set_sample_bit(evsel, TID);
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index 828ddd1..55ff958 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -45,6 +45,7 @@ enum {
> PERF_EVSEL__CONFIG_TERM_STACK_USER,
> PERF_EVSEL__CONFIG_TERM_INHERIT,
> PERF_EVSEL__CONFIG_TERM_MAX_STACK,
> + PERF_EVSEL__CONFIG_TERM_OVERWRITE,
> PERF_EVSEL__CONFIG_TERM_MAX,
> };
>
> @@ -59,6 +60,7 @@ struct perf_evsel_config_term {
> u64 stack_user;
> int max_stack;
> bool inherit;
> + bool overwrite;
> } val;
> };
>
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index d15e335..b641f75 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -901,6 +901,8 @@ static const char *config_term_names[__PARSE_EVENTS__TERM_TYPE_NR] = {
> [PARSE_EVENTS__TERM_TYPE_NOINHERIT] = "no-inherit",
> [PARSE_EVENTS__TERM_TYPE_INHERIT] = "inherit",
> [PARSE_EVENTS__TERM_TYPE_MAX_STACK] = "max-stack",
> + [PARSE_EVENTS__TERM_TYPE_OVERWRITE] = "overwrite",
> + [PARSE_EVENTS__TERM_TYPE_NOOVERWRITE] = "no-overwrite",
> };
>
> static bool config_term_shrinked;
> @@ -993,6 +995,12 @@ do { \
> case PARSE_EVENTS__TERM_TYPE_NOINHERIT:
> CHECK_TYPE_VAL(NUM);
> break;
> + case PARSE_EVENTS__TERM_TYPE_OVERWRITE:
> + CHECK_TYPE_VAL(NUM);
> + break;
> + case PARSE_EVENTS__TERM_TYPE_NOOVERWRITE:
> + CHECK_TYPE_VAL(NUM);
> + break;
> case PARSE_EVENTS__TERM_TYPE_NAME:
> CHECK_TYPE_VAL(STR);
> break;
> @@ -1045,6 +1053,8 @@ static int config_term_tracepoint(struct perf_event_attr *attr,
> case PARSE_EVENTS__TERM_TYPE_INHERIT:
> case PARSE_EVENTS__TERM_TYPE_NOINHERIT:
> case PARSE_EVENTS__TERM_TYPE_MAX_STACK:
> + case PARSE_EVENTS__TERM_TYPE_OVERWRITE:
> + case PARSE_EVENTS__TERM_TYPE_NOOVERWRITE:
> return config_term_common(attr, term, err);
> default:
> if (err) {
> @@ -1117,6 +1127,12 @@ do { \
> case PARSE_EVENTS__TERM_TYPE_MAX_STACK:
> ADD_CONFIG_TERM(MAX_STACK, max_stack, term->val.num);
> break;
> + case PARSE_EVENTS__TERM_TYPE_OVERWRITE:
> + ADD_CONFIG_TERM(OVERWRITE, overwrite, term->val.num ? 1 : 0);
> + break;
> + case PARSE_EVENTS__TERM_TYPE_NOOVERWRITE:
> + ADD_CONFIG_TERM(OVERWRITE, overwrite, term->val.num ? 0 : 1);
> + break;
> default:
> break;
> }
> @@ -2330,9 +2346,9 @@ static void config_terms_list(char *buf, size_t buf_sz)
> char *parse_events_formats_error_string(char *additional_terms)
> {
> char *str;
> - /* "branch_type" is the longest name */
> + /* "no-overwrite" is the longest name */
> char static_terms[__PARSE_EVENTS__TERM_TYPE_NR *
> - (sizeof("branch_type") - 1)];
> + (sizeof("no-overwrite") - 1)];
>
> config_terms_list(static_terms, sizeof(static_terms));
> /* valid terms */
> diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
> index 46c05cc..1b04d82 100644
> --- a/tools/perf/util/parse-events.h
> +++ b/tools/perf/util/parse-events.h
> @@ -69,6 +69,8 @@ enum {
> PARSE_EVENTS__TERM_TYPE_NOINHERIT,
> PARSE_EVENTS__TERM_TYPE_INHERIT,
> PARSE_EVENTS__TERM_TYPE_MAX_STACK,
> + PARSE_EVENTS__TERM_TYPE_NOOVERWRITE,
> + PARSE_EVENTS__TERM_TYPE_OVERWRITE,
> __PARSE_EVENTS__TERM_TYPE_NR,
> };
>
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 3c15b33..7a25194 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -202,6 +202,8 @@ stack-size { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_STACKSIZE); }
> max-stack { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_MAX_STACK); }
> inherit { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_INHERIT); }
> no-inherit { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_NOINHERIT); }
> +overwrite { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_OVERWRITE); }
> +no-overwrite { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_NOOVERWRITE); }
> , { return ','; }
> "/" { BEGIN(INITIAL); return '/'; }
> {name_minus} { return str(yyscanner, PE_NAME); }
> --
> 1.8.3.4

Next message: Andrew Morton: "Re: [PATCH] mm: slab.h: use ilog2() in kmalloc_index()"
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In reply to: Wang Nan: "[PATCH v8 6/8] perf tools: Enable overwrite settings"
Next in thread: Wang Nan: "[PATCH v8 4/8] perf record: Introduce rec->overwrite_evlist for overwritable events"
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