Re: [PATCH] perf, record: Add clockid parameter

[Stephane Eranian]

On Fri, Mar 27, 2015 at 2:59 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Fri, Mar 27, 2015 at 05:15:34PM -0300, Arnaldo Carvalho de Melo wrote:
>> I.e. we're back to the sys_perf_event_open() error reporting suckz rockz
>> thing, this time with PeterZ trying to find a way to avoid getting back
>> to that discussion... /me runz... ;-P
>
> :-)
>
> Not entirely, its just that I've not seen this userspace code in years
> and I'm pretty clueless.
>
> How about so then?
>
> ---
> Subject: perf, record: Add clockid parameter
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Date: Fri, 27 Mar 2015 15:32:01 +0100
>
> Teach perf-record about the new perf_event_attr::{use_clockid, clockid}
> fields. Add a simple parameter to set the clock (if any) to be used for
> the events to be recorded into the data file.
>
> Since we store the entire perf_event_attr in the EVENT_DESC section we
> also already store the used clockid in the data file.
>
> Cc: acme@xxxxxxxxxx
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>
>  tools/perf/Documentation/perf-record.txt |    5 +++
>  tools/perf/builtin-record.c              |    3 ++
>  tools/perf/perf.h                        |    1
>  tools/perf/util/evsel.c                  |   44 ++++++++++++++++++++++++++++---
>  4 files changed, 49 insertions(+), 4 deletions(-)
>
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -250,6 +250,11 @@ is off by default.
>  --running-time::
>  Record running and enabled time for read events (:S)
>
> +-k::
> +--clockid::
> +Sets the clock id to use for the various time fields in the perf_event_type
> +records. See clock_gettime().
> +
>  SEE ALSO
>  --------
>  linkperf:perf-stat[1], linkperf:perf-list[1]
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -739,6 +739,7 @@ static struct record record = {
>                         .uses_mmap   = true,
>                         .default_per_cpu = true,
>                 },
> +               .clockid             = -1,
>         },
>         .tool = {
>                 .sample         = process_sample_event,
> @@ -842,6 +843,8 @@ struct option __record_options[] = {
>                     "Sample machine registers on interrupt"),
>         OPT_BOOLEAN(0, "running-time", &record.opts.running_time,
>                     "Record running/enabled time of read (:S) events"),
> +       OPT_INTEGER('k', "clockid", &record.opts.clockid,
> +                   "clockid to use for events"),

I think you'd want a symbolic name for the clock to make this easier
on the user.

>         OPT_END()
>  };
>
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -62,6 +62,7 @@ struct record_opts {
>         u64          user_interval;
>         bool         sample_transaction;
>         unsigned     initial_delay;
> +       clockid_t    clockid;
>  };
>
>  struct option;
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -32,6 +32,7 @@ static struct {
>         bool exclude_guest;
>         bool mmap2;
>         bool cloexec;
> +       bool clockid;
>  } perf_missing_features;
>
>  static int perf_evsel__no_extra_init(struct perf_evsel *evsel __maybe_unused)
> @@ -761,6 +762,11 @@ void perf_evsel__config(struct perf_evse
>                 attr->disabled = 0;
>                 attr->enable_on_exec = 0;
>         }
> +
> +       if (opts->clockid >= 0) {
> +               attr->use_clockid = 1;
> +               attr->clockid = opts->clockid;
> +       }
>  }
>
>  static int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
> @@ -1036,7 +1042,6 @@ static size_t perf_event_attr__fprintf(s
>         ret += PRINT_ATTR2(exclude_user, exclude_kernel);
>         ret += PRINT_ATTR2(exclude_hv, exclude_idle);
>         ret += PRINT_ATTR2(mmap, comm);
> -       ret += PRINT_ATTR2(mmap2, comm_exec);
>         ret += PRINT_ATTR2(freq, inherit_stat);
>         ret += PRINT_ATTR2(enable_on_exec, task);
>         ret += PRINT_ATTR2(watermark, precise_ip);
> @@ -1044,6 +1049,8 @@ static size_t perf_event_attr__fprintf(s
>         ret += PRINT_ATTR2(exclude_host, exclude_guest);
>         ret += PRINT_ATTR2N("excl.callchain_kern", exclude_callchain_kernel,
>                             "excl.callchain_user", exclude_callchain_user);
> +       ret += PRINT_ATTR2(mmap2, comm_exec);
> +       ret += __PRINT_ATTR("%u",,use_clockid);
>
>         ret += PRINT_ATTR_U32(wakeup_events);
>         ret += PRINT_ATTR_U32(wakeup_watermark);
> @@ -1055,6 +1062,7 @@ static size_t perf_event_attr__fprintf(s
>         ret += PRINT_ATTR_X64(branch_sample_type);
>         ret += PRINT_ATTR_X64(sample_regs_user);
>         ret += PRINT_ATTR_U32(sample_stack_user);
> +       ret += PRINT_ATTR_U32(clockid);
>         ret += PRINT_ATTR_X64(sample_regs_intr);
>
>         ret += fprintf(fp, "%.60s\n", graph_dotted_line);
> @@ -1085,6 +1093,8 @@ static int __perf_evsel__open(struct per
>         }
>
>  fallback_missing_features:
> +       if (perf_missing_features.clockid)
> +               evsel->attr.use_clockid = 0;
>         if (perf_missing_features.cloexec)
>                 flags &= ~(unsigned long)PERF_FLAG_FD_CLOEXEC;
>         if (perf_missing_features.mmap2)
> @@ -1122,6 +1132,16 @@ static int __perf_evsel__open(struct per
>                                 goto try_fallback;
>                         }
>                         set_rlimit = NO_CHANGE;
> +
> +                       /*
> +                        * If we succeeded but had to kill clockid, fail and
> +                        * have perf_evsel__open_strerror() print us a nice
> +                        * error.
> +                        */
> +                       if (perf_missing_features.clockid) {
> +                               err = -EINVAL;
> +                               goto out_close;
> +                       }
>                 }
>         }
>
> @@ -1155,7 +1175,10 @@ static int __perf_evsel__open(struct per
>         if (err != -EINVAL || cpu > 0 || thread > 0)
>                 goto out_close;
>
> -       if (!perf_missing_features.cloexec && (flags & PERF_FLAG_FD_CLOEXEC)) {
> +       if (!perf_missing_features.clockid && evsel->attr.use_clockid) {
> +               perf_missing_features.clockid = true;
> +               goto fallback_missing_features;
> +       } else if (!perf_missing_features.cloexec && (flags & PERF_FLAG_FD_CLOEXEC)) {
>                 perf_missing_features.cloexec = true;
>                 goto fallback_missing_features;
>         } else if (!perf_missing_features.mmap2 && evsel->attr.mmap2) {
> @@ -2063,9 +2086,7 @@ int perf_evsel__fprintf(struct perf_evse
>                 if_print(exclude_hv);
>                 if_print(exclude_idle);
>                 if_print(mmap);
> -               if_print(mmap2);
>                 if_print(comm);
> -               if_print(comm_exec);
>                 if_print(freq);
>                 if_print(inherit_stat);
>                 if_print(enable_on_exec);
> @@ -2076,10 +2097,19 @@ int perf_evsel__fprintf(struct perf_evse
>                 if_print(sample_id_all);
>                 if_print(exclude_host);
>                 if_print(exclude_guest);
> +               if_print(exclude_callchain_kernel);
> +               if_print(exclude_callchain_user);
> +               if_print(mmap2);
> +               if_print(comm_exec);
> +               if_print(use_clockid);
>                 if_print(__reserved_1);
>                 if_print(wakeup_events);
>                 if_print(bp_type);
>                 if_print(branch_sample_type);
> +               if_print(sample_regs_user);
> +               if_print(sample_stack_user);
> +               if_print(clockid);
> +               if_print(sample_regs_intr);
>         }
>  out:
>         fputc('\n', fp);
> @@ -2158,6 +2188,12 @@ int perf_evsel__open_strerror(struct per
>         "The PMU counters are busy/taken by another profiler.\n"
>         "We found oprofile daemon running, please stop it and try again.");
>                 break;
> +
> +       case EINVAL:
> +               if (perf_missing_features.clockid)
> +                       return scnprintf(msg, size, "%s", "clockid not supported.");
> +               break;
> +
>         default:
>                 break;
>         }
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