Re: [PATCH v4 2/5] perf stat: Basic support for iostat in perf

[Namhyung Kim <namhyung@kernel.org>]

On Wed, Feb 3, 2021 at 10:58 PM Alexander Antonov
<alexander.antonov@linux.intel.com> wrote:
>
> Add basic flow for a new iostat mode in perf. Mode is intended to
> provide four I/O performance metrics per each PCIe root port: Inbound Read,
> Inbound Write, Outbound Read, Outbound Write.
>
> The actual code to compute the metrics and attribute it to
> root port is in follow-on patches.
>
> Signed-off-by: Alexander Antonov <alexander.antonov@linux.intel.com>
> ---
>  tools/perf/builtin-stat.c      | 31 ++++++++++++++++++++++++++
>  tools/perf/util/iostat.h       | 32 +++++++++++++++++++++++++++
>  tools/perf/util/stat-display.c | 40 +++++++++++++++++++++++++++++++++-
>  tools/perf/util/stat-shadow.c  | 11 +++++++++-
>  tools/perf/util/stat.h         |  1 +
>  5 files changed, 113 insertions(+), 2 deletions(-)
>  create mode 100644 tools/perf/util/iostat.h
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 60fdb6a0805f..66c913692120 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -65,6 +65,7 @@
>  #include "util/target.h"
>  #include "util/time-utils.h"
>  #include "util/top.h"
> +#include "util/iostat.h"
>  #include "asm/bug.h"
>
>  #include <linux/time64.h>
> @@ -186,6 +187,7 @@ static struct perf_stat_config stat_config = {
>         .metric_only_len        = METRIC_ONLY_LEN,
>         .walltime_nsecs_stats   = &walltime_nsecs_stats,
>         .big_num                = true,
> +       .iostat_run             = false,
>  };
>
>  static inline void diff_timespec(struct timespec *r, struct timespec *a,
> @@ -723,6 +725,14 @@ static int parse_metric_groups(const struct option *opt,
>         return metricgroup__parse_groups(opt, str, &stat_config.metric_events);
>  }
>
> +__weak int iostat_parse(const struct option *opt __maybe_unused,
> +                        const char *str __maybe_unused,
> +                        int unset __maybe_unused)
> +{
> +       pr_err("iostat mode is not supported\n");
> +       return -1;
> +}
> +
>  static struct option stat_options[] = {
>         OPT_BOOLEAN('T', "transaction", &transaction_run,
>                     "hardware transaction statistics"),
> @@ -803,6 +813,8 @@ static struct option stat_options[] = {
>         OPT_CALLBACK('M', "metrics", &evsel_list, "metric/metric group list",
>                      "monitor specified metrics or metric groups (separated by ,)",
>                      parse_metric_groups),
> +       OPT_CALLBACK_OPTARG(0, "iostat", &evsel_list, &stat_config, "root port",
> +                           "measure PCIe metrics per root port", iostat_parse),

Can we make the help string and default argument more generic?
Something like "measure IO metrics provided by arch/platform"
and the default value being "default". :)


>         OPT_END()
>  };
>
> @@ -1131,6 +1143,12 @@ __weak void arch_topdown_group_warn(void)
>  {
>  }
>
> +__weak int iostat_list(struct evlist *evlist __maybe_unused,
> +                       struct perf_stat_config *config __maybe_unused)
> +{
> +       return 0;
> +}
> +
>  /*
>   * Add default attributes, if there were no attributes specified or
>   * if -d/--detailed, -d -d or -d -d -d is used:
> @@ -1682,6 +1700,10 @@ static void setup_system_wide(int forks)
>         }
>  }
>
> +__weak void iostat_release(struct evlist *evlist __maybe_unused)
> +{
> +}
> +
>  int cmd_stat(int argc, const char **argv)
>  {
>         const char * const stat_usage[] = {
> @@ -1858,6 +1880,12 @@ int cmd_stat(int argc, const char **argv)
>                 goto out;
>         }
>
> +       if (stat_config.iostat_run) {
> +               status = iostat_list(evsel_list, &stat_config);

I think it's unnatural to call iostat_list() unconditionally here.
How about this?

    status = iostat_prepare(...);
    if (status < 0)
        goto out;

    if (status == IOSTAT_LIST)
        iostat_list(...);
    else
        ...


> +               if (status || !stat_config.iostat_run)
> +                       goto out;
> +       }
> +
>         if (add_default_attributes())
>                 goto out;
>
> @@ -2008,6 +2036,9 @@ int cmd_stat(int argc, const char **argv)
>         perf_stat__exit_aggr_mode();
>         perf_evlist__free_stats(evsel_list);
>  out:
> +       if (stat_config.iostat_run)
> +               iostat_release(evsel_list);
> +
>         zfree(&stat_config.walltime_run);
>
>         if (smi_cost && smi_reset)
> diff --git a/tools/perf/util/iostat.h b/tools/perf/util/iostat.h
> new file mode 100644
> index 000000000000..b34ebedfd5e6
> --- /dev/null
> +++ b/tools/perf/util/iostat.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * perf iostat
> + *
> + * Copyright (C) 2020, Intel Corporation
> + *
> + * Authors: Alexander Antonov <alexander.antonov@linux.intel.com>
> + */
> +
> +#ifndef _IOSTAT_H
> +#define _IOSTAT_H
> +
> +#include <subcmd/parse-options.h>
> +#include "util/stat.h"
> +#include "util/parse-events.h"
> +#include "util/evlist.h"
> +
> +struct option;
> +struct perf_stat_config;
> +struct evlist;
> +struct timespec;
> +
> +int iostat_parse(const struct option *opt, const char *str,
> +                int unset __maybe_unused);
> +void iostat_prefix(struct perf_stat_config *config, struct evlist *evlist,
> +                  char *prefix, struct timespec *ts);
> +void iostat_print_metric(struct perf_stat_config *config, struct evsel *evsel,
> +                        struct perf_stat_output_ctx *out);
> +int iostat_list(struct evlist *evlist, struct perf_stat_config *config);
> +void iostat_release(struct evlist *evlist);
> +
> +#endif /* _IOSTAT_H */
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index db1bec115d0b..de78cf6962b9 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -16,6 +16,7 @@
>  #include <linux/ctype.h>
>  #include "cgroup.h"
>  #include <api/fs/fs.h>
> +#include "iostat.h"
>
>  #define CNTR_NOT_SUPPORTED     "<not supported>"
>  #define CNTR_NOT_COUNTED       "<not counted>"
> @@ -302,6 +303,11 @@ static void print_metric_header(struct perf_stat_config *config,
>         struct outstate *os = ctx;
>         char tbuf[1024];
>
> +       /* In case of iostat, print metric header for first root port only */
> +       if (config->iostat_run &&
> +           os->evsel->priv != os->evsel->evlist->selected->priv)
> +               return;
> +
>         if (!valid_only_metric(unit))
>                 return;
>         unit = fixunit(tbuf, os->evsel, unit);
> @@ -936,6 +942,8 @@ static void print_metric_headers(struct perf_stat_config *config,
>                         fputs("time,", config->output);
>                 fputs(aggr_header_csv[config->aggr_mode], config->output);
>         }
> +       if (config->iostat_run && !config->interval && !config->csv_output)
> +               fprintf(config->output, "   port         ");

It's too specific to the current implementation.
Let's make it a callback or a weak function.


>
>         /* Print metrics headers only */
>         evlist__for_each_entry(evlist, counter) {
> @@ -954,6 +962,13 @@ static void print_metric_headers(struct perf_stat_config *config,
>         fputc('\n', config->output);
>  }
>
> +__weak void iostat_prefix(struct perf_stat_config *config __maybe_unused,
> +                         struct evlist *evlist __maybe_unused,
> +                         char *prefix __maybe_unused,
> +                         struct timespec *ts __maybe_unused)
> +{
> +}
> +
>  static void print_interval(struct perf_stat_config *config,
>                            struct evlist *evlist,
>                            char *prefix, struct timespec *ts)
> @@ -966,7 +981,10 @@ static void print_interval(struct perf_stat_config *config,
>         if (config->interval_clear)
>                 puts(CONSOLE_CLEAR);
>
> -       sprintf(prefix, "%6lu.%09lu%s", ts->tv_sec, ts->tv_nsec, config->csv_sep);
> +       if (!config->iostat_run)
> +               sprintf(prefix, "%6lu.%09lu%s", ts->tv_sec,
> +                                               ts->tv_nsec,
> +                                               config->csv_sep);
>
>         if ((num_print_interval == 0 && !config->csv_output) || config->interval_clear) {
>                 switch (config->aggr_mode) {
> @@ -996,6 +1014,7 @@ static void print_interval(struct perf_stat_config *config,
>                                 fprintf(output, "                  counts %*s events\n", unit_width, "unit");
>                         break;
>                 case AGGR_PCIE_PORT:
> +                       fprintf(output, "#           time    port        ");

Ditto.

>                         break;
>                 case AGGR_GLOBAL:
>                 default:
> @@ -1174,6 +1193,10 @@ perf_evlist__print_counters(struct evlist *evlist,
>         int interval = config->interval;
>         struct evsel *counter;
>         char buf[64], *prefix = NULL;
> +       void *perf_device = NULL;
> +
> +       if (config->iostat_run)
> +               evlist->selected = evlist__first(evlist);
>
>         if (interval)
>                 print_interval(config, evlist, prefix = buf, ts);
> @@ -1222,6 +1245,21 @@ perf_evlist__print_counters(struct evlist *evlist,
>                 }
>                 break;
>         case AGGR_PCIE_PORT:

Ditto.  Something like iostat_print_counters().

> +               counter = evlist__first(evlist);
> +               perf_evlist__set_selected(evlist, counter);
> +               iostat_prefix(config, evlist, prefix = buf, ts);
> +               fprintf(config->output, "%s", prefix);
> +               evlist__for_each_entry(evlist, counter) {
> +                       perf_device = evlist->selected->priv;
> +                       if (perf_device && perf_device != counter->priv) {
> +                               perf_evlist__set_selected(evlist, counter);
> +                               iostat_prefix(config, evlist, prefix, ts);
> +                               fprintf(config->output, "\n%s", prefix);
> +                       }
> +                       print_counter_aggr(config, counter, prefix);

I'm not sure but do you assume each counter has different priv?
I don't know if the output is correct (like call iostat_prefix() once
and call print_counter_aggr() twice) when they have same one.

> +                       if ((counter->idx + 1) == evlist->core.nr_entries)
> +                               fputc('\n', config->output);

Can we just move this out of the loop?

Thanks,
Namhyung


> +               }
>                 break;
>         case AGGR_UNSET:
>         default:
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index 2c41d47f6f83..083a450c6dc7 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/tools/perf/util/stat-shadow.c
> @@ -9,6 +9,7 @@
>  #include "expr.h"
>  #include "metricgroup.h"
>  #include <linux/zalloc.h>
> +#include "iostat.h"
>
>  /*
>   * AGGR_GLOBAL: Use CPU 0
> @@ -814,6 +815,12 @@ static void generic_metric(struct perf_stat_config *config,
>                 zfree(&pctx.ids[i].name);
>  }
>
> +__weak void iostat_print_metric(struct perf_stat_config *config __maybe_unused,
> +                               struct evsel *evsel __maybe_unused,
> +                               struct perf_stat_output_ctx *out __maybe_unused)
> +{
> +}
> +
>  void perf_stat__print_shadow_stats(struct perf_stat_config *config,
>                                    struct evsel *evsel,
>                                    double avg, int cpu,
> @@ -829,7 +836,9 @@ void perf_stat__print_shadow_stats(struct perf_stat_config *config,
>         struct metric_event *me;
>         int num = 1;
>
> -       if (perf_evsel__match(evsel, HARDWARE, HW_INSTRUCTIONS)) {
> +       if (config->iostat_run) {
> +               iostat_print_metric(config, evsel, out);
> +       } else if (perf_evsel__match(evsel, HARDWARE, HW_INSTRUCTIONS)) {
>                 total = runtime_stat_avg(st, STAT_CYCLES, ctx, cpu);
>
>                 if (total) {
> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
> index c7544c28c02a..c2a2b28effd6 100644
> --- a/tools/perf/util/stat.h
> +++ b/tools/perf/util/stat.h
> @@ -107,6 +107,7 @@ struct perf_stat_config {
>         bool                     big_num;
>         bool                     no_merge;
>         bool                     walltime_run_table;
> +       bool                     iostat_run;
>         FILE                    *output;
>         unsigned int             interval;
>         unsigned int             timeout;
> --
> 2.19.1
>