[PATCH RFC 07/10] perf,tools: record counter statistics during sampling

[kan . liang]

From: Kan Liang <kan.liang@xxxxxxxxx>

Reading at the start and the end of sampling, and save the counter
statistics value to PERF_RECORD_STAT_READ.
The absolate value from counter will be stored in prev_raw_counts. The
detla value will be caculated and saved in PERF_RECORD_STAT_READ.

Signed-off-by: Kan Liang <kan.liang@xxxxxxxxx>
---
 tools/perf/builtin-record.c | 76 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 75 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 5b09318..0e5e4c0 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -29,6 +29,7 @@
 #include "util/data.h"
 #include "util/auxtrace.h"
 #include "util/parse-branch-options.h"
+#include "util/stat.h"
 
 #include <unistd.h>
 #include <sched.h>
@@ -266,6 +267,30 @@ int auxtrace_record__snapshot_start(struct auxtrace_record *itr __maybe_unused)
 
 #endif
 
+static void
+free_prev_stat_counts(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->prev_raw_counts != NULL)
+			perf_evsel__free_prev_raw_counts(evsel);
+	}
+}
+
+static int perf_evlist__alloc_prev_stat(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->stat_read &&
+		    (perf_evsel__alloc_prev_raw_counts(evsel, cpu_map__nr(evsel->cpus), 1) < 0))
+				return -ENOMEM;
+	}
+
+	return 0;
+}
+
 static int record__open(struct record *rec)
 {
 	char msg[512];
@@ -352,6 +377,9 @@ try_again:
 		goto out;
 	}
 
+	if (perf_evlist__alloc_prev_stat(evlist))
+		goto out;
+
 	session->evlist = evlist;
 	perf_session__set_id_hdr_size(session);
 out:
@@ -427,6 +455,50 @@ static struct perf_event_header finished_round_event = {
 	.type = PERF_RECORD_FINISHED_ROUND,
 };
 
+static void process_stat_read_event(struct record *rec, int id,
+				    struct perf_evsel *pos,
+				    struct perf_counts_values *count,
+				    u32 pos_id)
+{
+	union perf_event ev;
+	struct perf_counts_values tmp;
+
+	memset(&ev, 0, sizeof(ev));
+	ev.stat_read.header.type = PERF_RECORD_STAT_READ;
+	ev.stat_read.header.size = sizeof(ev.stat_read);
+	ev.stat_read.cpu = pos->cpus->map[id];
+	ev.stat_read.pos_id = pos_id;
+
+	BUG_ON(pos->prev_raw_counts == NULL);
+	tmp.val = perf_counts(pos->prev_raw_counts, id, 0)->val;
+	if (tmp.val)
+		ev.stat_read.value = count->val - tmp.val;
+	perf_counts(pos->prev_raw_counts, id, 0)->val = count->val;
+
+	ev.stat_read.time = rdclock();
+
+	record__write(rec, &ev, sizeof(ev.stat_read));
+}
+
+static void perf_read_counter(struct record *rec)
+{
+	struct perf_evlist *evlist = rec->evlist;
+	struct perf_counts_values count;
+	struct perf_evsel *pos;
+	int cpu;
+	u32 pos_id = 0;
+
+	evlist__for_each(evlist, pos) {
+		for (cpu = 0; cpu < cpu_map__nr(pos->cpus); cpu++) {
+			if (pos->stat_read &&
+			    !perf_evsel__read(pos, cpu, 0, &count)) {
+				process_stat_read_event(rec, cpu, pos, &count, pos_id);
+			}
+		}
+		pos_id++;
+	}
+}
+
 static int record__mmap_read_all(struct record *rec)
 {
 	u64 bytes_written = rec->bytes_written;
@@ -664,6 +736,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		perf_evlist__enable(rec->evlist);
 	}
 
+	perf_read_counter(rec);
 	auxtrace_snapshot_enabled = 1;
 	for (;;) {
 		int hits = rec->samples;
@@ -708,6 +781,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		 */
 		if (done && !disabled && !target__none(&opts->target)) {
 			auxtrace_snapshot_enabled = 0;
+			perf_read_counter(rec);
 			perf_evlist__disable(rec->evlist);
 			disabled = true;
 		}
@@ -776,7 +850,7 @@ out_child:
 			perf_data_file__size(file) / 1024.0 / 1024.0,
 			file->path, samples);
 	}
-
+	free_prev_stat_counts(rec->evlist);
 out_delete_session:
 	perf_session__delete(session);
 	return status;
-- 
1.8.3.1

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