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Subject[PATCH v13 4/8] perf record: Introduce rec->overwrite_evlist for overwritable events
Date
Create an auxiliary evlist for overwritable events.

Before mmap, build this evlist and set 'overwrite' and 'backward'
attribute. Since perf_evlist__mmap_ex() only maps events when
evsel->overwrite matches evlist's corresponding attributes, with
these two evlists an event goes to either rec->evlist or
rec->overwrite_evlist.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: pi3orama@163.com
---
tools/perf/builtin-record.c | 59 ++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 56 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index b2b3b60..3b62295 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -51,6 +51,7 @@ struct record {
struct perf_data_file file;
struct auxtrace_record *itr;
struct perf_evlist *evlist;
+ struct perf_evlist *overwrite_evlist;
struct perf_session *session;
const char *progname;
int realtime_prio;
@@ -342,13 +343,41 @@ int auxtrace_record__snapshot_start(struct auxtrace_record *itr __maybe_unused)

#endif

+static int record__create_overwrite_evlist(struct record *rec)
+{
+ struct perf_evlist *evlist = rec->evlist;
+ struct perf_evsel *pos;
+
+ evlist__for_each_entry(evlist, pos) {
+ if (!pos->attr.write_backward)
+ continue;
+
+ if (!rec->overwrite_evlist) {
+ rec->overwrite_evlist = perf_evlist__new_aux(evlist);
+ if (rec->overwrite_evlist) {
+ rec->overwrite_evlist->backward = true;
+ rec->overwrite_evlist->overwrite = true;
+ return 0;
+ } else
+ return -ENOMEM;
+ }
+ }
+ return 0;
+}
+
static int record__mmap_evlist(struct record *rec,
- struct perf_evlist *evlist)
+ struct perf_evlist *evlist,
+ bool overwrite)
{
struct record_opts *opts = &rec->opts;
char msg[512];

- if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, false,
+ /*
+ * Don't use evlist->overwrite because it is logically an
+ * internal attribute and is set by perf_evlist__mmap_ex().
+ * Avoid circular dependency.
+ */
+ if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, overwrite,
opts->auxtrace_mmap_pages,
opts->auxtrace_snapshot_mode) < 0) {
if (errno == EPERM) {
@@ -373,7 +402,23 @@ static int record__mmap_evlist(struct record *rec,

static int record__mmap(struct record *rec)
{
- return record__mmap_evlist(rec, rec->evlist);
+ int err;
+
+ err = record__create_overwrite_evlist(rec);
+ if (err)
+ return err;
+
+ err = record__mmap_evlist(rec, rec->evlist, false);
+ if (err)
+ return err;
+
+ if (!rec->overwrite_evlist)
+ return 0;
+
+ err = record__mmap_evlist(rec, rec->overwrite_evlist, true);
+ if (err)
+ return err;
+ return 0;
}

static int record__open(struct record *rec)
@@ -698,9 +743,14 @@ static const struct perf_event_mmap_page *record__pick_pc(struct record *rec)
{
const struct perf_event_mmap_page *pc;

+ /* Change it to a loop if a new aux evlist is added */
pc = perf_evlist__pick_pc(rec->evlist);
if (pc)
return pc;
+ pc = perf_evlist__pick_pc(rec->overwrite_evlist);
+ if (pc)
+ return pc;
+
return NULL;
}

@@ -1311,6 +1361,7 @@ static struct record record = {
.mmap2 = perf_event__process_mmap2,
.ordered_events = true,
},
+ .overwrite_evlist = NULL,
};

const char record_callchain_help[] = CALLCHAIN_RECORD_HELP
@@ -1614,6 +1665,8 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
err = __cmd_record(&record, argc, argv);
out_symbol_exit:
perf_evlist__delete(rec->evlist);
+ if (rec->overwrite_evlist)
+ perf_evlist__delete(rec->overwrite_evlist);
symbol__exit();
auxtrace_record__free(rec->itr);
return err;
--
1.8.3.4
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