Re: [PATCH v5 02/10] perf record: implement -f,--mmap-flush= option

Jiri Olsa
2019-03-05T12:26:02Z

On Fri, Mar 01, 2019 at 06:41:44PM +0300, Alexey Budankov wrote:

SNIP

> static int process_synthesized_event(struct perf_tool *tool,
> union perf_event *event,
> struct perf_sample *sample __maybe_unused,
> @@ -543,7 +566,8 @@ static int record__mmap_evlist(struct record *rec,
> if (perf_evlist__mmap_ex(evlist, opts->mmap_pages,
> opts->auxtrace_mmap_pages,
> opts->auxtrace_snapshot_mode,
> - opts->nr_cblocks, opts->affinity) < 0) {
> + opts->nr_cblocks, opts->affinity,
> + opts->mmap_flush) < 0) {
> if (errno == EPERM) {
> pr_err("Permission error mapping pages.\n"
> "Consider increasing "
> @@ -733,7 +757,7 @@ static void record__adjust_affinity(struct record *rec, struct perf_mmap *map)
> }
>
> static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evlist,
> - bool overwrite)
> + bool overwrite, bool sync)
> {
> u64 bytes_written = rec->bytes_written;
> int i;
> @@ -756,12 +780,19 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
> off = record__aio_get_pos(trace_fd);
>
> for (i = 0; i < evlist->nr_mmaps; i++) {
> + u64 flush = MMAP_FLUSH_DEFAULT;

hum, why does this need the initial value?

> struct perf_mmap *map = &maps[i];
>
> if (map->base) {
> record__adjust_affinity(rec, map);
> + if (sync) {
> + flush = map->flush;
> + map->flush = MMAP_FLUSH_DEFAULT;
> + }
> if (!record__aio_enabled(rec)) {
> if (perf_mmap__push(map, rec, record__pushfn) != 0) {
> + if (sync)
> + map->flush = flush;
> rc = -1;
> goto out;
> }
> @@ -774,10 +805,14 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
> idx = record__aio_sync(map, false);
> if (perf_mmap__aio_push(map, rec, idx, record__aio_pushfn, &off) != 0) {
> record__aio_set_pos(trace_fd, off);
> + if (sync)
> + map->flush = flush;
> rc = -1;
> goto out;
> }
> }
> + if (sync)
> + map->flush = flush;

is there a point to set this back in case of sync == true?
we are going out at this point, right?

jirka