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

[Peter Zijlstra]

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"),
 	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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