Commit 1f2b7fbb authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
Browse files

perf annotate: Save branch counters for each block 



When annotating a basic block, it's useful to display the occurrences
of other events in the block.

The branch counter feature is only available for newer Intel platforms.

So a dedicated option to display the branch counters is not introduced.

Reuse the existing --total-cycles option, which triggers the annotation
of a basic block and displays the cycle-related annotation.

When the branch counters information is available, the branch counters
are automatically appended after all the cycle-related annotation.

Accounting the branch counters as well when accounting the cycles in
hist__account_cycles().

In 'struct annotated_branch', introduce a br_cntr array to save the
accumulation of each branch counter.

In a sample, all the branch counters for a branch are saved in a u64
space.

Because the saturation of a branch counter is small, e.g., for Intel
Sierra Forest, the saturation is only 3.

Add ANNOTATION__BR_CNTR_SATURATED_FLAG to indicate if a branch counter
once saturated. That can be used to indicate a potential event lost
because of the saturation.

Reviewed-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240813160208.2493643-5-kan.liang@linux.intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 3a867a6d

tools/perf/builtin-annotate.c

+2 −1
Original line number Diff line number Diff line
@@ -221,7 +221,8 @@ static int process_branch_callback(struct evsel *evsel, 
	if (a.map != NULL)

		dso__set_hit(map__dso(a.map));



	hist__account_cycles(sample->branch_stack, al, sample, false, NULL);

	hist__account_cycles(sample->branch_stack, al, sample, false,

			     NULL, evsel);



	ret = hist_entry_iter__add(&iter, &a, PERF_MAX_STACK_DEPTH, ann);

out:

tools/perf/builtin-diff.c

+2 −2
Original line number Diff line number Diff line
@@ -431,8 +431,8 @@ static int diff__process_sample_event(const struct perf_tool *tool, 
			goto out;

		}



		hist__account_cycles(sample->branch_stack, &al, sample, false,

				     NULL);

		hist__account_cycles(sample->branch_stack, &al, sample,

				     false, NULL, evsel);

		break;



	case COMPUTE_STREAM:

tools/perf/builtin-report.c

+1 −1
Original line number Diff line number Diff line
@@ -328,7 +328,7 @@ static int process_sample_event(const struct perf_tool *tool, 
	if (ui__has_annotation() || rep->symbol_ipc || rep->total_cycles_mode) {

		hist__account_cycles(sample->branch_stack, &al, sample,

				     rep->nonany_branch_mode,

				     &rep->total_cycles);

				     &rep->total_cycles, evsel);

	}



	ret = hist_entry_iter__add(&iter, &al, rep->max_stack, rep);

tools/perf/builtin-top.c

+2 −2
Original line number Diff line number Diff line
@@ -736,7 +736,7 @@ static int hist_iter__top_callback(struct hist_entry_iter *iter, 


	hist__account_cycles(iter->sample->branch_stack, al, iter->sample,

			     !(top->record_opts.branch_stack & PERF_SAMPLE_BRANCH_ANY),

		     NULL);

			     NULL, evsel);

	return 0;

}

tools/perf/util/annotate.c

+56 −12
Original line number Diff line number Diff line
@@ -266,22 +266,30 @@ struct annotated_branch *annotation__get_branch(struct annotation *notes) 
	return notes->branch;

}



static struct cyc_hist *symbol__cycles_hist(struct symbol *sym)

static struct annotated_branch *symbol__find_branch_hist(struct symbol *sym,

							 unsigned int br_cntr_nr)

{

	struct annotation *notes = symbol__annotation(sym);

	struct annotated_branch *branch;

	const size_t size = symbol__size(sym);



	branch = annotation__get_branch(notes);

	if (branch == NULL)

		return NULL;



	if (branch->cycles_hist == NULL) {

		const size_t size = symbol__size(sym);



		branch->cycles_hist = calloc(size, sizeof(struct cyc_hist));

		if (!branch->cycles_hist)

			return NULL;

	}



	if (br_cntr_nr && branch->br_cntr == NULL) {

		branch->br_cntr = calloc(br_cntr_nr * size, sizeof(u64));

		if (!branch->br_cntr)

			return NULL;

	}



	return branch->cycles_hist;

	return branch;

}



struct annotated_source *symbol__hists(struct symbol *sym, int nr_hists)
@@ -316,16 +324,44 @@ static int symbol__inc_addr_samples(struct map_symbol *ms, 
	return src ? __symbol__inc_addr_samples(ms, src, evsel->core.idx, addr, sample) : 0;

}



static int symbol__account_cycles(u64 addr, u64 start,

				  struct symbol *sym, unsigned cycles)

static int symbol__account_br_cntr(struct annotated_branch *branch,

				   struct evsel *evsel,

				   unsigned offset,

				   u64 br_cntr)

{

	struct cyc_hist *cycles_hist;

	unsigned int br_cntr_nr = evsel__leader(evsel)->br_cntr_nr;

	unsigned int base = evsel__leader(evsel)->br_cntr_idx;

	unsigned int width = evsel__env(evsel)->br_cntr_width;

	unsigned int off = offset * evsel->evlist->nr_br_cntr;

	unsigned int i, mask = (1L << width) - 1;

	u64 *branch_br_cntr = branch->br_cntr;



	if (!br_cntr || !branch_br_cntr)

		return 0;



	for (i = 0; i < br_cntr_nr; i++) {

		u64 cntr = (br_cntr >> i * width) & mask;



		branch_br_cntr[off + i + base] += cntr;

		if (cntr == mask)

			branch_br_cntr[off + i + base] |= ANNOTATION__BR_CNTR_SATURATED_FLAG;

	}



	return 0;

}



static int symbol__account_cycles(u64 addr, u64 start, struct symbol *sym,

				  unsigned cycles, struct evsel *evsel,

				  u64 br_cntr)

{

	struct annotated_branch *branch;

	unsigned offset;

	int ret;



	if (sym == NULL)

		return 0;

	cycles_hist = symbol__cycles_hist(sym);

	if (cycles_hist == NULL)

	branch = symbol__find_branch_hist(sym, evsel->evlist->nr_br_cntr);

	if (!branch)

		return -ENOMEM;

	if (addr < sym->start || addr >= sym->end)

		return -ERANGE;
@@ -337,15 +373,22 @@ static int symbol__account_cycles(u64 addr, u64 start, 
			start = 0;

	}

	offset = addr - sym->start;

	return __symbol__account_cycles(cycles_hist,

	ret = __symbol__account_cycles(branch->cycles_hist,

					start ? start - sym->start : 0,

					offset, cycles,

					!!start);



	if (ret)

		return ret;



	return symbol__account_br_cntr(branch, evsel, offset, br_cntr);

}



int addr_map_symbol__account_cycles(struct addr_map_symbol *ams,

				    struct addr_map_symbol *start,

				    unsigned cycles)

				    unsigned cycles,

				    struct evsel *evsel,

				    u64 br_cntr)

{

	u64 saddr = 0;

	int err;
@@ -371,7 +414,7 @@ int addr_map_symbol__account_cycles(struct addr_map_symbol *ams, 
			start ? start->addr : 0,

			ams->ms.sym ? ams->ms.sym->start + map__start(ams->ms.map) : 0,

			saddr);

	err = symbol__account_cycles(ams->al_addr, saddr, ams->ms.sym, cycles);

	err = symbol__account_cycles(ams->al_addr, saddr, ams->ms.sym, cycles, evsel, br_cntr);

	if (err)

		pr_debug2("account_cycles failed %d\n", err);

	return err;
@@ -412,6 +455,7 @@ static void annotated_branch__delete(struct annotated_branch *branch) 
{

	if (branch) {

		zfree(&branch->cycles_hist);

		free(branch->br_cntr);

		free(branch);

	}

}