Re: [PATCH 1/2] perf, record: Add clockid parameter

Peter Zijlstra
2015-04-07T15:49:10Z

On Tue, Apr 07, 2015 at 11:09:53AM +0200, Peter Zijlstra wrote:
> @@ -739,6 +813,7 @@ static struct record record = {
> .uses_mmap = true,
> .default_per_cpu = true,
> },
> + .clockid = -1,
> },

As spotted by dahern this is not working well for all other record_opts
instances, fix that by adding a use_clockid field just like
perf_event_attr has.

perf test does (now) not appear to fail more with this patch than without.

---
Subject: perf, record: Add clockid parameter
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 31 Mar 2015 00:19:31 +0200

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: eranian@google.com
Cc: dsahern@gmail.com
Cc: acme@redhat.com
Cc: jolsa@redhat.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/perf/Documentation/perf-record.txt | 7 ++
tools/perf/builtin-record.c | 80 +++++++++++++++++++++++++++++++
tools/perf/perf.h | 2
tools/perf/util/evsel.c | 59 +++++++++++++++++++++-
tools/perf/util/header.c | 3 +
5 files changed, 147 insertions(+), 4 deletions(-)

--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -250,6 +250,13 @@ 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(). In particular CLOCK_MONOTONIC and
+CLOCK_MONOTONIC_RAW are supported, some events might also allow
+CLOCK_BOOTTIME, CLOCK_REALTIME and CLOCK_TAI.
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -711,6 +711,83 @@ static int perf_record_config(const char
return perf_default_config(var, value, cb);
}

+struct clockid_map {
+ const char *name;
+ int clockid;
+};
+
+#define CLOCKID_MAP(n, c) \
+ { .name = n, .clockid = (c), }
+
+#define CLOCKID_END { .name = NULL, }
+
+/*
+ * Doesn't appear to have made it into userspace so define here if missing.
+ */
+#ifndef CLOCK_TAI
+#define CLOCK_TAI 11
+#endif
+
+static const struct clockid_map clockids[] = {
+ /* available for all events, NMI safe */
+ CLOCKID_MAP("monotonic", CLOCK_MONOTONIC),
+ CLOCKID_MAP("monotonic_raw", CLOCK_MONOTONIC_RAW),
+
+ /* available for some events */
+ CLOCKID_MAP("realtime", CLOCK_REALTIME),
+ CLOCKID_MAP("boottime", CLOCK_BOOTTIME),
+ CLOCKID_MAP("tai", CLOCK_TAI),
+
+ /* available for the lazy */
+ CLOCKID_MAP("mono", CLOCK_MONOTONIC),
+ CLOCKID_MAP("raw", CLOCK_MONOTONIC_RAW),
+ CLOCKID_MAP("real", CLOCK_REALTIME),
+ CLOCKID_MAP("boot", CLOCK_BOOTTIME),
+
+ CLOCKID_END,
+};
+
+static int parse_clockid(const struct option *opt, const char *str, int unset)
+{
+ struct record_opts *opts = (struct record_opts *)opt->value;
+ const struct clockid_map *cm;
+ const char *ostr = str;
+
+ if (unset) {
+ opts->use_clockid = 0;
+ return 0;
+ }
+
+ /* no arg passed */
+ if (!str)
+ return 0;
+
+ /* no setting it twice */
+ if (opts->use_clockid)
+ return -1;
+
+ opts->use_clockid = true;
+
+ /* if its a number, we're done */
+ if (sscanf(str, "%d", &opts->clockid) == 1)
+ return 0;
+
+ /* allow a "CLOCK_" prefix to the name */
+ if (!strncasecmp(str, "CLOCK_", 6))
+ str += 6;
+
+ for (cm = clockids; cm->name; cm++) {
+ if (!strcasecmp(str, cm->name)) {
+ opts->clockid = cm->clockid;
+ return 0;
+ }
+ }
+
+ opts->use_clockid = false;
+ ui__warning("unknown clockid %s, check man page\n", ostr);
+ return -1;
+}
+
static const char * const __record_usage[] = {
"perf record [<options>] [<command>]",
"perf record [<options>] -- <command> [<options>]",
@@ -842,6 +919,9 @@ 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_CALLBACK('k', "clockid", &record.opts,
+ "clockid", "clockid to use for events, see clock_gettime()",
+ parse_clockid),
OPT_END()
};

--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -62,6 +62,8 @@ struct record_opts {
u64 user_interval;
bool sample_transaction;
unsigned initial_delay;
+ bool use_clockid;
+ clockid_t clockid;
};

struct option;
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -32,8 +32,12 @@ static struct {
bool exclude_guest;
bool mmap2;
bool cloexec;
+ bool clockid;
+ bool clockid_wrong;
} perf_missing_features;

+static clockid_t clockid;
+
static int perf_evsel__no_extra_init(struct perf_evsel *evsel __maybe_unused)
{
return 0;
@@ -761,6 +765,12 @@ void perf_evsel__config(struct perf_evse
attr->disabled = 0;
attr->enable_on_exec = 0;
}
+
+ clockid = opts->clockid;
+ if (opts->use_clockid) {
+ attr->use_clockid = 1;
+ attr->clockid = opts->clockid;
+ }
}

static int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
@@ -1036,7 +1046,6 @@ 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 +1053,9 @@ 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 +1067,7 @@ 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 +1098,12 @@ static int __perf_evsel__open(struct per
}

fallback_missing_features:
+ if (perf_missing_features.clockid_wrong)
+ evsel->attr.clockid = CLOCK_MONOTONIC; /* should always work */
+ if (perf_missing_features.clockid) {
+ evsel->attr.use_clockid = 0;
+ evsel->attr.clockid = 0;
+ }
if (perf_missing_features.cloexec)
flags &= ~(unsigned long)PERF_FLAG_FD_CLOEXEC;
if (perf_missing_features.mmap2)
@@ -1122,6 +1141,17 @@ 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 ||
+ perf_missing_features.clockid_wrong) {
+ err = -EINVAL;
+ goto out_close;
+ }
}
}

@@ -1155,7 +1185,17 @@ 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)) {
+ /*
+ * Must probe features in the order they were added to the
+ * perf_event_attr interface.
+ */
+ if (!perf_missing_features.clockid_wrong && evsel->attr.use_clockid) {
+ perf_missing_features.clockid_wrong = true;
+ goto fallback_missing_features;
+ } else 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 +2103,7 @@ 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 +2114,17 @@ int perf_evsel__fprintf(struct perf_evse
if_print(sample_id_all);
if_print(exclude_host);
if_print(exclude_guest);
+ 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 +2203,12 @@ 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, "clockid feature not supported.");
+ if (perf_missing_features.clockid_wrong)
+ return scnprintf(msg, size, "wrong clockid (%d).", clockid);
+ break;
default:
break;
}
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1098,6 +1098,9 @@ static void print_event_desc(struct perf
}
fprintf(fp, " }");
}
+ if (evsel->attr.use_clockid)
+ fprintf(fp, ", clockid = %d", evsel->attr.clockid);
+

fputc('\n', fp);
}