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Date: Wed, 18 Mar 2020 16:49:37 -0300
From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To: kan.liang@...ux.intel.com
Cc: jolsa@...hat.com, peterz@...radead.org, mingo@...hat.com,
linux-kernel@...r.kernel.org, namhyung@...nel.org,
adrian.hunter@...el.com, mathieu.poirier@...aro.org,
ravi.bangoria@...ux.ibm.com, alexey.budankov@...ux.intel.com,
vitaly.slobodskoy@...el.com, pavel.gerasimov@...el.com,
mpe@...erman.id.au, eranian@...gle.com, ak@...ux.intel.com
Subject: Re: [PATCH V3 02/17] perf header: Support CPU PMU capabilities
Em Fri, Mar 13, 2020 at 11:33:04AM -0700, kan.liang@...ux.intel.com escreveu:
> From: Kan Liang <kan.liang@...ux.intel.com>
>
> 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.
>
> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> ---
> .../Documentation/perf.data-file-format.txt | 16 +++
> tools/perf/util/env.h | 3 +
> tools/perf/util/header.c | 110 ++++++++++++++++++
> tools/perf/util/header.h | 1 +
> 4 files changed, 130 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/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");
please combine decl + assign:
+ struct perf_pmu *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))) {
Why can't you play use list_for_each_entry() here and remove that perf_pmu__scan_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;
ditto
> + 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
>
--
- Arnaldo
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