[PATCH V2 2/9] perf header: Support CPU PMU capabilities

kan.liang
2020-03-09T17:48:01Z

To stitch LBR call stack, the max LBR information is required. So the
CPU PMU capabilities information has to be stored in perf header.

Add a new feature HEADER_CPU_PMU_CAPS for CPU PMU capabilities.
Retrieve all CPU PMU capabilities, not just max LBR information.

Add variable max_branches to facilitate future usage.

The CPU PMU capabilities information is only useful for LBR call stack
mode. Clear the feature for perf stat and other perf record mode.

Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
.../Documentation/perf.data-file-format.txt | 16 +++
tools/perf/builtin-record.c | 3 +
tools/perf/builtin-stat.c | 1 +
tools/perf/util/env.h | 3 +
tools/perf/util/header.c | 110 ++++++++++++++++++
tools/perf/util/header.h | 1 +
6 files changed, 134 insertions(+)

diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index b0152e1095c5..b6472e463284 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -373,6 +373,22 @@ struct {
Indicates that trace contains records of PERF_RECORD_COMPRESSED type
that have perf_events records in compressed form.

+ HEADER_CPU_PMU_CAPS = 28,
+
+ A list of cpu PMU capabilities. The format of data is as below.
+
+struct {
+ u32 nr_cpu_pmu_caps;
+ {
+ char name[];
+ char value[];
+ } [nr_cpu_pmu_caps]
+};
+
+
+Example:
+ cpu pmu capabilities: branches=32, max_precise=3, pmu_name=icelake
+
other bits are reserved and should ignored for now
HEADER_FEAT_BITS = 256,

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4c301466101b..428f7f5b8e48 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1120,6 +1120,9 @@ static void record__init_features(struct record *rec)
if (!record__comp_enabled(rec))
perf_header__clear_feat(&session->header, HEADER_COMPRESSED);

+ if (!callchain_param.enabled || (callchain_param.record_mode != CALLCHAIN_LBR))
+ perf_header__clear_feat(&session->header, HEADER_CPU_PMU_CAPS);
+
perf_header__clear_feat(&session->header, HEADER_STAT);
}

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index ec053dc1e35c..b5c8a5ab5e75 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1595,6 +1595,7 @@ static void init_features(struct perf_session *session)
perf_header__clear_feat(&session->header, HEADER_TRACING_DATA);
perf_header__clear_feat(&session->header, HEADER_BRANCH_STACK);
perf_header__clear_feat(&session->header, HEADER_AUXTRACE);
+ perf_header__clear_feat(&session->header, HEADER_CPU_PMU_CAPS);
}

static int __cmd_record(int argc, const char **argv)
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index 11d05ae3606a..d286d478b4d8 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -48,6 +48,7 @@ struct perf_env {
char *cpuid;
unsigned long long total_mem;
unsigned int msr_pmu_type;
+ unsigned int max_branches;

int nr_cmdline;
int nr_sibling_cores;
@@ -57,12 +58,14 @@ struct perf_env {
int nr_memory_nodes;
int nr_pmu_mappings;
int nr_groups;
+ int nr_cpu_pmu_caps;
char *cmdline;
const char **cmdline_argv;
char *sibling_cores;
char *sibling_dies;
char *sibling_threads;
char *pmu_mappings;
+ char *cpu_pmu_caps;
struct cpu_topology_map *cpu;
struct cpu_cache_level *caches;
int caches_cnt;
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index acbd046bf95c..ce29321a4e1d 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1395,6 +1395,39 @@ static int write_compressed(struct feat_fd *ff __maybe_unused,
return do_write(ff, &(ff->ph->env.comp_mmap_len), sizeof(ff->ph->env.comp_mmap_len));
}

+static int write_cpu_pmu_caps(struct feat_fd *ff,
+ struct evlist *evlist __maybe_unused)
+{
+ struct perf_pmu_caps *caps = NULL;
+ struct perf_pmu *cpu_pmu;
+ int nr_caps;
+ int ret;
+
+ cpu_pmu = perf_pmu__find("cpu");
+ if (!cpu_pmu)
+ return -ENOENT;
+
+ nr_caps = perf_pmu__caps_parse(cpu_pmu);
+ if (nr_caps < 0)
+ return nr_caps;
+
+ ret = do_write(ff, &nr_caps, sizeof(nr_caps));
+ if (ret < 0)
+ return ret;
+
+ while ((caps = perf_pmu__scan_caps(cpu_pmu, caps))) {
+ ret = do_write_string(ff, caps->name);
+ if (ret < 0)
+ return ret;
+
+ ret = do_write_string(ff, caps->value);
+ if (ret < 0)
+ return ret;
+ }
+
+ return ret;
+}
+
static void print_hostname(struct feat_fd *ff, FILE *fp)
{
fprintf(fp, "# hostname : %s\n", ff->ph->env.hostname);
@@ -1809,6 +1842,28 @@ static void print_compressed(struct feat_fd *ff, FILE *fp)
ff->ph->env.comp_level, ff->ph->env.comp_ratio);
}

+static void print_cpu_pmu_caps(struct feat_fd *ff, FILE *fp)
+{
+ const char *delimiter = "# cpu pmu capabilities: ";
+ char *str;
+ u32 nr_caps;
+
+ nr_caps = ff->ph->env.nr_cpu_pmu_caps;
+ if (!nr_caps) {
+ fprintf(fp, "# cpu pmu capabilities: not available\n");
+ return;
+ }
+
+ str = ff->ph->env.cpu_pmu_caps;
+ while (nr_caps--) {
+ fprintf(fp, "%s%s", delimiter, str);
+ delimiter = ", ";
+ str += strlen(str) + 1;
+ }
+
+ fprintf(fp, "\n");
+}
+
static void print_pmu_mappings(struct feat_fd *ff, FILE *fp)
{
const char *delimiter = "# pmu mappings: ";
@@ -2846,6 +2901,60 @@ static int process_compressed(struct feat_fd *ff,
return 0;
}

+static int process_cpu_pmu_caps(struct feat_fd *ff,
+ void *data __maybe_unused)
+{
+ char *name, *value;
+ struct strbuf sb;
+ u32 nr_caps;
+
+ if (do_read_u32(ff, &nr_caps))
+ return -1;
+
+ if (!nr_caps) {
+ pr_debug("cpu pmu capabilities not available\n");
+ return 0;
+ }
+
+ ff->ph->env.nr_cpu_pmu_caps = nr_caps;
+
+ if (strbuf_init(&sb, 128) < 0)
+ return -1;
+
+ while (nr_caps--) {
+ name = do_read_string(ff);
+ if (!name)
+ goto error;
+
+ value = do_read_string(ff);
+ if (!value)
+ goto free_name;
+
+ if (strbuf_addf(&sb, "%s=%s", name, value) < 0)
+ goto free_value;
+
+ /* include a NULL character at the end */
+ if (strbuf_add(&sb, "", 1) < 0)
+ goto free_value;
+
+ if (!strcmp(name, "branches"))
+ ff->ph->env.max_branches = atoi(value);
+
+ free(value);
+ free(name);
+ }
+ ff->ph->env.cpu_pmu_caps = strbuf_detach(&sb, NULL);
+ return 0;
+
+free_value:
+ free(value);
+free_name:
+ free(name);
+error:
+ strbuf_release(&sb);
+ return -1;
+}
+
#define FEAT_OPR(n, func, __full_only) \
[HEADER_##n] = { \
.name = __stringify(n), \
@@ -2903,6 +3012,7 @@ const struct perf_header_feature_ops feat_ops[HEADER_LAST_FEATURE] = {
FEAT_OPR(BPF_PROG_INFO, bpf_prog_info, false),
FEAT_OPR(BPF_BTF, bpf_btf, false),
FEAT_OPR(COMPRESSED, compressed, false),
+ FEAT_OPR(CPU_PMU_CAPS, cpu_pmu_caps, false),
};

struct header_print_data {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 840f95cee349..650bd1c7a99b 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -43,6 +43,7 @@ enum {
HEADER_BPF_PROG_INFO,
HEADER_BPF_BTF,
HEADER_COMPRESSED,
+ HEADER_CPU_PMU_CAPS,
HEADER_LAST_FEATURE,
HEADER_FEAT_BITS = 256,
};
--
2.17.1