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perf annotate: Save branch counters for each block

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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: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Namhyung 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Kan Liang
2024-08-13 09:02:03 -07:00
committed by Arnaldo Carvalho de Melo
parent 3a867a6dad
commit 1f2b7fbb04
10 changed files with 80 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
tools/perf/util/annotate.c
View File

@@ -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;
}
return branch->cycles_hist;
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;
}
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);
}
}