Re: [PATCH 6/9] perf report: Display the branch counter histogram

Liang, Kan
2024-08-06T14:39:57Z

On 2024-08-02 8:18 p.m., Namhyung Kim wrote:
> On Wed, Jul 3, 2024 at 1:03 PM <kan.liang@linux.intel.com> wrote:
>>
>> From: Kan Liang <kan.liang@linux.intel.com>
>>
>> Reusing the existing --total-cycles option to display the branch
>> counters. Add a new PERF_HPP_REPORT__BLOCK_BRANCH_COUNTER to display
>> the logged branch counter events. They are shown right after all the
>> cycle-related annotations.
>> Extend the struct block_info to store and pass the branch counter
>> related information.
>>
>> The annotation_br_cntr_entry() is to print the histogram of each branch
>> counter event.
>> The annotation_br_cntr_abbr_list() prints the branch counter's
>> abbreviation list. Press 'B' to display the list in the TUI mode.
>>
>> $perf record -e "{branch-instructions:ppp,branch-misses}:S" -j any,counter
>> $perf report --total-cycles --stdio
>>
>> # To display the perf.data header info, please use --header/--header-only options.
>> #
>> #
>> # Total Lost Samples: 0
>> #
>> # Samples: 1M of events 'anon group { branch-instructions:ppp, branch-misses }'
>> # Event count (approx.): 1610046
>> #
>> # Branch counter abbr list:
>> # branch-instructions:ppp = A
>> # branch-misses = B
>> # '-' No event occurs
>> # '+' Event occurrences may be lost due to branch counter saturated
>> #
>> # Sampled Cycles% Sampled Cycles Avg Cycles% Avg Cycles Branch Counter [Program Block Range]
>> # ............... .............. ........... .......... ...................... ..................
>> #
>> 57.55% 2.5M 0.00% 3 |A |- | ...
>> 25.27% 1.1M 0.00% 2 |AA |- | ...
>> 15.61% 667.2K 0.00% 1 |A |- | ...
>> 0.16% 6.9K 0.81% 575 |A |- | ...
>> 0.16% 6.8K 1.38% 977 |AA |- | ...
>> 0.16% 6.8K 0.04% 28 |AA |B | ...
>> 0.15% 6.6K 1.33% 946 |A |- | ...
>> 0.11% 4.5K 0.06% 46 |AAA+|- | ...
>> 0.10% 4.4K 0.88% 624 |A |- | ...
>> 0.09% 3.7K 0.74% 524 |AAA+|B | ...
>
> I think this format assumes short width and might not work
> well when it has more events with bigger width. Maybe
> A=<n>, B=<n> ?

The purpose of "AAA" is to print a histogram here which can give the end
user a straightforward image of the distribution. The A=<n> may not be
that obvious.

I don't think there is a plan to increase the saturation of the counter.
So 4 bits of width should last for a long time. Other ARCHs don't have
such a feature either. I think I can the change the code to force the 4
bits of width now. For more that 3 events, the perf tool can convert it
to a "+". We may update the perf tool for a more specific histogram
later, if the saturation is changed. What do you think?

Thanks,
Kan
>
> Thanks,
> Namhyung
>
>>
>> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>> ---
>> tools/perf/Documentation/perf-report.txt | 1 +
>> tools/perf/builtin-diff.c | 4 +-
>> tools/perf/builtin-report.c | 20 ++++-
>> tools/perf/ui/browsers/hists.c | 17 +++-
>> tools/perf/util/annotate.c | 101 +++++++++++++++++++++++
>> tools/perf/util/annotate.h | 3 +
>> tools/perf/util/block-info.c | 66 +++++++++++++--
>> tools/perf/util/block-info.h | 8 +-
>> 8 files changed, 202 insertions(+), 18 deletions(-)
>>
>> diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
>> index d2b1593ef700..f35189d5ff1e 100644
>> --- a/tools/perf/Documentation/perf-report.txt
>> +++ b/tools/perf/Documentation/perf-report.txt
>> @@ -614,6 +614,7 @@ include::itrace.txt[]
>> 'Avg Cycles%' - block average sampled cycles / sum of total block average
>> sampled cycles
>> 'Avg Cycles' - block average sampled cycles
>> + 'Branch Counter' - block branch counter histogram
>>
>> --skip-empty::
>> Do not print 0 results in the --stat output.
>> diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
>> index 2d9226b1de52..de24892dc7b8 100644
>> --- a/tools/perf/builtin-diff.c
>> +++ b/tools/perf/builtin-diff.c
>> @@ -705,7 +705,7 @@ static void hists__precompute(struct hists *hists)
>> if (compute == COMPUTE_CYCLES) {
>> bh = container_of(he, struct block_hist, he);
>> init_block_hist(bh);
>> - block_info__process_sym(he, bh, NULL, 0);
>> + block_info__process_sym(he, bh, NULL, 0, 0);
>> }
>>
>> data__for_each_file_new(i, d) {
>> @@ -728,7 +728,7 @@ static void hists__precompute(struct hists *hists)
>> pair_bh = container_of(pair, struct block_hist,
>> he);
>> init_block_hist(pair_bh);
>> - block_info__process_sym(pair, pair_bh, NULL, 0);
>> + block_info__process_sym(pair, pair_bh, NULL, 0, 0);
>>
>> bh = container_of(he, struct block_hist, he);
>>
>> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
>> index da8d13bbb500..a0f864f2e996 100644
>> --- a/tools/perf/builtin-report.c
>> +++ b/tools/perf/builtin-report.c
>> @@ -575,6 +575,13 @@ static int evlist__tty_browse_hists(struct evlist *evlist, struct report *rep, c
>> hists__fprintf_nr_sample_events(hists, rep, evname, stdout);
>>
>> if (rep->total_cycles_mode) {
>> + char *buf;
>> +
>> + if (!annotation_br_cntr_abbr_list(&buf, pos, true)) {
>> + fprintf(stdout, "%s", buf);
>> + fprintf(stdout, "#\n");
>> + free(buf);
>> + }
>> report__browse_block_hists(&rep->block_reports[i - 1].hist,
>> rep->min_percent, pos, NULL);
>> continue;
>> @@ -1121,18 +1128,23 @@ static int __cmd_report(struct report *rep)
>> report__output_resort(rep);
>>
>> if (rep->total_cycles_mode) {
>> - int block_hpps[6] = {
>> + int nr_hpps = 4;
>> + int block_hpps[PERF_HPP_REPORT__BLOCK_MAX_INDEX] = {
>> PERF_HPP_REPORT__BLOCK_TOTAL_CYCLES_PCT,
>> PERF_HPP_REPORT__BLOCK_LBR_CYCLES,
>> PERF_HPP_REPORT__BLOCK_CYCLES_PCT,
>> PERF_HPP_REPORT__BLOCK_AVG_CYCLES,
>> - PERF_HPP_REPORT__BLOCK_RANGE,
>> - PERF_HPP_REPORT__BLOCK_DSO,
>> };
>>
>> + if (session->evlist->nr_br_cntr > 0)
>> + block_hpps[nr_hpps++] = PERF_HPP_REPORT__BLOCK_BRANCH_COUNTER;
>> +
>> + block_hpps[nr_hpps++] = PERF_HPP_REPORT__BLOCK_RANGE;
>> + block_hpps[nr_hpps++] = PERF_HPP_REPORT__BLOCK_DSO;
>> +
>> rep->block_reports = block_info__create_report(session->evlist,
>> rep->total_cycles,
>> - block_hpps, 6,
>> + block_hpps, nr_hpps,
>> &rep->nr_block_reports);
>> if (!rep->block_reports)
>> return -1;
>> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
>> index b7219df51236..73d766eac75b 100644
>> --- a/tools/perf/ui/browsers/hists.c
>> +++ b/tools/perf/ui/browsers/hists.c
>> @@ -3684,8 +3684,10 @@ int block_hists_tui_browse(struct block_hist *bh, struct evsel *evsel,
>> struct hist_browser *browser;
>> int key = -1;
>> struct popup_action action;
>> + char *br_cntr_text = NULL;
>> static const char help[] =
>> - " q Quit \n";
>> + " q Quit \n"
>> + " B Branch counter abbr list (Optional)\n";
>>
>> browser = hist_browser__new(hists);
>> if (!browser)
>> @@ -3703,6 +3705,8 @@ int block_hists_tui_browse(struct block_hist *bh, struct evsel *evsel,
>>
>> memset(&action, 0, sizeof(action));
>>
>> + annotation_br_cntr_abbr_list(&br_cntr_text, evsel, false);
>> +
>> while (1) {
>> key = hist_browser__run(browser, "? - help", true, 0);
>>
>> @@ -3723,6 +3727,16 @@ int block_hists_tui_browse(struct block_hist *bh, struct evsel *evsel,
>> action.ms.sym = browser->selection->sym;
>> do_annotate(browser, &action);
>> continue;
>> + case 'B':
>> + if (br_cntr_text) {
>> + ui__question_window("Branch counter abbr list",
>> + br_cntr_text, "Press any key...", 0);
>> + } else {
>> + ui__question_window("Branch counter abbr list",
>> + "\n The branch counter is not available.\n",
>> + "Press any key...", 0);
>> + }
>> + continue;
>> default:
>> break;
>> }
>> @@ -3730,5 +3744,6 @@ int block_hists_tui_browse(struct block_hist *bh, struct evsel *evsel,
>>
>> out:
>> hist_browser__delete(browser);
>> + free(br_cntr_text);
>> return 0;
>> }
>> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
>> index 6baa0671598e..f20f9e40ef0d 100644
>> --- a/tools/perf/util/annotate.c
>> +++ b/tools/perf/util/annotate.c
>> @@ -40,6 +40,7 @@
>> #include "namespaces.h"
>> #include "thread.h"
>> #include "hashmap.h"
>> +#include "strbuf.h"
>> #include <regex.h>
>> #include <linux/bitops.h>
>> #include <linux/kernel.h>
>> @@ -47,6 +48,7 @@
>> #include <linux/zalloc.h>
>> #include <subcmd/parse-options.h>
>> #include <subcmd/run-command.h>
>> +#include <math.h>
>>
>> /* FIXME: For the HE_COLORSET */
>> #include "ui/browser.h"
>> @@ -1706,6 +1708,105 @@ static void ipc_coverage_string(char *bf, int size, struct annotation *notes)
>> ipc, coverage);
>> }
>>
>> +int annotation_br_cntr_abbr_list(char **str, struct evsel *evsel, bool header)
>> +{
>> + struct evsel *pos;
>> + struct strbuf sb;
>> +
>> + if (evsel->evlist->nr_br_cntr <= 0)
>> + return -ENOTSUP;
>> +
>> + strbuf_init(&sb, /*hint=*/ 0);
>> +
>> + if (header && strbuf_addf(&sb, "# Branch counter abbr list:\n"))
>> + goto err;
>> +
>> + evlist__for_each_entry(evsel->evlist, pos) {
>> + if (!(pos->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS))
>> + continue;
>> + if (header && strbuf_addf(&sb, "#"))
>> + goto err;
>> +
>> + if (strbuf_addf(&sb, " %s = %s\n", pos->name, pos->abbr_name))
>> + goto err;
>> + }
>> +
>> + if (header && strbuf_addf(&sb, "#"))
>> + goto err;
>> + if (strbuf_addf(&sb, " '-' No event occurs\n"))
>> + goto err;
>> +
>> + if (header && strbuf_addf(&sb, "#"))
>> + goto err;
>> + if (strbuf_addf(&sb, " '+' Event occurrences may be lost due to branch counter saturated\n"))
>> + goto err;
>> +
>> + *str = strbuf_detach(&sb, NULL);
>> +
>> + return 0;
>> +err:
>> + strbuf_release(&sb);
>> + return -ENOMEM;
>> +}
>> +
>> +int annotation_br_cntr_entry(char **str, int br_cntr_nr,
>> + u64 *br_cntr, int num_aggr,
>> + struct evsel *evsel)
>> +{
>> + struct evsel *pos = evsel ? evlist__first(evsel->evlist) : NULL;
>> + int i, j, avg, used;
>> + struct strbuf sb;
>> +
>> + strbuf_init(&sb, /*hint=*/ 0);
>> + for (i = 0; i < br_cntr_nr; i++) {
>> + used = 0;
>> + avg = ceil((double)(br_cntr[i] & ~ANNOTATION__BR_CNTR_SATURATED_FLAG) /
>> + (double)num_aggr);
>> +
>> + if (strbuf_addch(&sb, '|'))
>> + goto err;
>> +
>> + if (!br_cntr[i]) {
>> + if (strbuf_addch(&sb, '-'))
>> + goto err;
>> + used++;
>> + } else {
>> + evlist__for_each_entry_from(evsel->evlist, pos) {
>> + if ((pos->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS) &&
>> + (pos->br_cntr_idx == i))
>> + break;
>> + }
>> + for (j = 0; j < avg; j++, used++) {
>> + if (strbuf_addstr(&sb, pos->abbr_name))
>> + goto err;
>> + }
>> +
>> + if (br_cntr[i] & ANNOTATION__BR_CNTR_SATURATED_FLAG) {
>> + if (strbuf_addch(&sb, '+'))
>> + goto err;
>> + used++;
>> + }
>> + pos = list_next_entry(pos, core.node);
>> + }
>> +
>> + /* Assume the branch counter saturated at 3 */
>> + for (j = used; j < 4; j++) {
>> + if (strbuf_addch(&sb, ' '))
>> + goto err;
>> + }
>> + }
>> +
>> + if (strbuf_addch(&sb, br_cntr_nr ? '|' : ' '))
>> + goto err;
>> +
>> + *str = strbuf_detach(&sb, NULL);
>> +
>> + return 0;
>> +err:
>> + strbuf_release(&sb);
>> + return -ENOMEM;
>> +}
>> +
>> static void __annotation_line__write(struct annotation_line *al, struct annotation *notes,
>> bool first_line, bool current_entry, bool change_color, int width,
>> void *obj, unsigned int percent_type,
>> diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
>> index f39dd5d7b05e..2ff79a389dc0 100644
>> --- a/tools/perf/util/annotate.h
>> +++ b/tools/perf/util/annotate.h
>> @@ -548,4 +548,7 @@ struct annotated_basic_block {
>> int annotate_get_basic_blocks(struct symbol *sym, s64 src, s64 dst,
>> struct list_head *head);
>>
>> +int annotation_br_cntr_entry(char **str, int br_cntr_nr, u64 *br_cntr,
>> + int num_aggr, struct evsel *evsel);
>> +int annotation_br_cntr_abbr_list(char **str, struct evsel *evsel, bool header);
>> #endif /* __PERF_ANNOTATE_H */
>> diff --git a/tools/perf/util/block-info.c b/tools/perf/util/block-info.c
>> index 04068d48683f..649392bee7ed 100644
>> --- a/tools/perf/util/block-info.c
>> +++ b/tools/perf/util/block-info.c
>> @@ -40,16 +40,32 @@ static struct block_header_column {
>> [PERF_HPP_REPORT__BLOCK_DSO] = {
>> .name = "Shared Object",
>> .width = 20,
>> + },
>> + [PERF_HPP_REPORT__BLOCK_BRANCH_COUNTER] = {
>> + .name = "Branch Counter",
>> + .width = 30,
>> }
>> };
>>
>> -struct block_info *block_info__new(void)
>> +static struct block_info *block_info__new(unsigned int br_cntr_nr)
>> {
>> - return zalloc(sizeof(struct block_info));
>> + struct block_info *bi = zalloc(sizeof(struct block_info));
>> +
>> + if (bi && br_cntr_nr) {
>> + bi->br_cntr = calloc(br_cntr_nr, sizeof(u64));
>> + if (!bi->br_cntr) {
>> + free(bi);
>> + return NULL;
>> + }
>> + }
>> +
>> + return bi;
>> }
>>
>> void block_info__delete(struct block_info *bi)
>> {
>> + if (bi)
>> + free(bi->br_cntr);
>> free(bi);
>> }
>>
>> @@ -86,7 +102,8 @@ int64_t block_info__cmp(struct perf_hpp_fmt *fmt __maybe_unused,
>>
>> static void init_block_info(struct block_info *bi, struct symbol *sym,
>> struct cyc_hist *ch, int offset,
>> - u64 total_cycles)
>> + u64 total_cycles, unsigned int br_cntr_nr,
>> + u64 *br_cntr, struct evsel *evsel)
>> {
>> bi->sym = sym;
>> bi->start = ch->start;
>> @@ -99,10 +116,18 @@ static void init_block_info(struct block_info *bi, struct symbol *sym,
>>
>> memcpy(bi->cycles_spark, ch->cycles_spark,
>> NUM_SPARKS * sizeof(u64));
>> +
>> + if (br_cntr && br_cntr_nr) {
>> + bi->br_cntr_nr = br_cntr_nr;
>> + memcpy(bi->br_cntr, &br_cntr[offset * br_cntr_nr],
>> + br_cntr_nr * sizeof(u64));
>> + }
>> + bi->evsel = evsel;
>> }
>>
>> int block_info__process_sym(struct hist_entry *he, struct block_hist *bh,
>> - u64 *block_cycles_aggr, u64 total_cycles)
>> + u64 *block_cycles_aggr, u64 total_cycles,
>> + unsigned int br_cntr_nr)
>> {
>> struct annotation *notes;
>> struct cyc_hist *ch;
>> @@ -125,12 +150,14 @@ int block_info__process_sym(struct hist_entry *he, struct block_hist *bh,
>> struct block_info *bi;
>> struct hist_entry *he_block;
>>
>> - bi = block_info__new();
>> + bi = block_info__new(br_cntr_nr);
>> if (!bi)
>> return -1;
>>
>> init_block_info(bi, he->ms.sym, &ch[i], i,
>> - total_cycles);
>> + total_cycles, br_cntr_nr,
>> + notes->branch->br_cntr,
>> + hists_to_evsel(he->hists));
>> cycles += bi->cycles_aggr / bi->num_aggr;
>>
>> he_block = hists__add_entry_block(&bh->block_hists,
>> @@ -327,6 +354,24 @@ static void init_block_header(struct block_fmt *block_fmt)
>> fmt->width = block_column_width;
>> }
>>
>> +static int block_branch_counter_entry(struct perf_hpp_fmt *fmt,
>> + struct perf_hpp *hpp,
>> + struct hist_entry *he)
>> +{
>> + struct block_fmt *block_fmt = container_of(fmt, struct block_fmt, fmt);
>> + struct block_info *bi = he->block_info;
>> + char *buf;
>> + int ret;
>> +
>> + if (annotation_br_cntr_entry(&buf, bi->br_cntr_nr, bi->br_cntr,
>> + bi->num_aggr, bi->evsel))
>> + return 0;
>> +
>> + ret = scnprintf(hpp->buf, hpp->size, "%*s", block_fmt->width, buf);
>> + free(buf);
>> + return ret;
>> +}
>> +
>> static void hpp_register(struct block_fmt *block_fmt, int idx,
>> struct perf_hpp_list *hpp_list)
>> {
>> @@ -357,6 +402,9 @@ static void hpp_register(struct block_fmt *block_fmt, int idx,
>> case PERF_HPP_REPORT__BLOCK_DSO:
>> fmt->entry = block_dso_entry;
>> break;
>> + case PERF_HPP_REPORT__BLOCK_BRANCH_COUNTER:
>> + fmt->entry = block_branch_counter_entry;
>> + break;
>> default:
>> return;
>> }
>> @@ -390,7 +438,7 @@ static void init_block_hist(struct block_hist *bh, struct block_fmt *block_fmts,
>> static int process_block_report(struct hists *hists,
>> struct block_report *block_report,
>> u64 total_cycles, int *block_hpps,
>> - int nr_hpps)
>> + int nr_hpps, unsigned int br_cntr_nr)
>> {
>> struct rb_node *next = rb_first_cached(&hists->entries);
>> struct block_hist *bh = &block_report->hist;
>> @@ -405,7 +453,7 @@ static int process_block_report(struct hists *hists,
>> while (next) {
>> he = rb_entry(next, struct hist_entry, rb_node);
>> block_info__process_sym(he, bh, &block_report->cycles,
>> - total_cycles);
>> + total_cycles, br_cntr_nr);
>> next = rb_next(&he->rb_node);
>> }
>>
>> @@ -435,7 +483,7 @@ struct block_report *block_info__create_report(struct evlist *evlist,
>> struct hists *hists = evsel__hists(pos);
>>
>> process_block_report(hists, &block_reports[i], total_cycles,
>> - block_hpps, nr_hpps);
>> + block_hpps, nr_hpps, evlist->nr_br_cntr);
>> i++;
>> }
>>
>> diff --git a/tools/perf/util/block-info.h b/tools/perf/util/block-info.h
>> index 0b9e1aad4c55..b9329dc3ab59 100644
>> --- a/tools/perf/util/block-info.h
>> +++ b/tools/perf/util/block-info.h
>> @@ -18,6 +18,9 @@ struct block_info {
>> u64 total_cycles;
>> int num;
>> int num_aggr;
>> + int br_cntr_nr;
>> + u64 *br_cntr;
>> + struct evsel *evsel;
>> };
>>
>> struct block_fmt {
>> @@ -36,6 +39,7 @@ enum {
>> PERF_HPP_REPORT__BLOCK_AVG_CYCLES,
>> PERF_HPP_REPORT__BLOCK_RANGE,
>> PERF_HPP_REPORT__BLOCK_DSO,
>> + PERF_HPP_REPORT__BLOCK_BRANCH_COUNTER,
>> PERF_HPP_REPORT__BLOCK_MAX_INDEX
>> };
>>
>> @@ -46,7 +50,6 @@ struct block_report {
>> int nr_fmts;
>> };
>>
>> -struct block_info *block_info__new(void);
>> void block_info__delete(struct block_info *bi);
>>
>> int64_t __block_info__cmp(struct hist_entry *left, struct hist_entry *right);
>> @@ -55,7 +58,8 @@ int64_t block_info__cmp(struct perf_hpp_fmt *fmt __maybe_unused,
>> struct hist_entry *left, struct hist_entry *right);
>>
>> int block_info__process_sym(struct hist_entry *he, struct block_hist *bh,
>> - u64 *block_cycles_aggr, u64 total_cycles);
>> + u64 *block_cycles_aggr, u64 total_cycles,
>> + unsigned int br_cntr_nr);
>>
>> struct block_report *block_info__create_report(struct evlist *evlist,
>> u64 total_cycles,
>> --
>> 2.38.1
>>
>