[PATCH 49/49] perf record: Spread maps for --threads=X option

Jiri Olsa
2018-01-09T15:37:57Z

This code allows to create arbitrary number of threads
and assign maps for it.

Each thread gets a fair share of the data maps plus the
main thread gets also to read tracking maps.

The assignment is visible from --thread-stats output
(for --threads=2 on 4 CPUs system):

pid write poll skip maps (size 20K)
1s 9318 144B 1 0 18K 19K 17K 19K 19K 19K
9320 16K 3 3 19K 18K

There are 6 maps for thread 9318 (2 data maps and 4 auxiliary)
and 2 data maps for thread 9320. Each thread writes data to the
separate data file.

Link: http://lkml.kernel.org/n/tip-5myhg112a5mqv0ij0q7hky98@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/builtin-record.c | 103 +++++++++++++++++++++++++++++++++++++++++---
1 file changed, 98 insertions(+), 5 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6831601c292e..e3fca9ca4e32 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -420,6 +420,33 @@ static void record__mmap_index_all(struct record *rec)
}
}

+static void record__mmap_index_cnt(struct record *rec)
+{
+ struct perf_evlist *evlist = rec->evlist;
+ struct perf_data *data = &rec->data;
+ int i, t;
+
+ for (i = 0; i < evlist->nr_mmaps; i++) {
+ struct perf_mmap *map = &evlist->track_mmap[i];
+
+ map->file = &data->file;
+ }
+
+ for (t = 0; t < rec->threads_cnt; t++) {
+ struct record_thread *th = rec->threads + t;
+ int nr = th->mmap_nr;
+
+ if (!t)
+ nr -= evlist->nr_mmaps;
+
+ for (i = 0; i < nr; i++) {
+ struct perf_mmap *map = th->mmap[i];
+
+ map->file = &data->index[t];
+ }
+ }
+}
+
static int record__mmap_index(struct record *rec)
{
struct perf_data *data = &rec->data;
@@ -433,6 +460,8 @@ static int record__mmap_index(struct record *rec)
record__mmap_index_all(rec);
else if (rec->threads_one)
record__mmap_index_single(rec);
+ else
+ record__mmap_index_cnt(rec);

return 0;
}
@@ -1139,6 +1168,70 @@ record__threads_assign_all(struct record *rec)
}

static int
+record__threads_assign_cnt(struct record *rec)
+{
+ struct record_thread *threads = rec->threads;
+ struct record_thread *thread0 = threads;
+ struct perf_evlist *evlist = rec->evlist;
+ int cnt = rec->threads_cnt;
+ int i, j, t, nr, nr_trk, nr_thr, nr_mod, n0 = 0;
+
+ nr = evlist->mmap ? evlist->nr_mmaps : 0;
+ nr_trk = evlist->track_mmap ? evlist->nr_mmaps : 0;
+
+ nr_thr = nr / cnt;
+ nr_mod = nr % cnt;
+
+ /*
+ * Create threads' mmaps first..
+ */
+ for (t = 0; t < cnt; t++) {
+ struct record_thread *th = threads + t;
+ int n = nr_thr;
+
+ /* evenly spread the remainder of threads */
+ n += (nr_mod-- > 0) ? 1 : 0;
+
+ /* first thread deals with track mmaps */
+ if (!t) {
+ n0 = n;
+ n += nr_trk;
+ }
+
+ if (record_thread__mmap(th, n, 0))
+ return -ENOMEM;
+ }
+
+ /*
+ * ... and assign mmaps separatelly.
+ */
+
+ j = 0; /* mmap in evlist->mmap */
+ i = 0; /* mmap in thread */
+
+ while (1) {
+ for (t = 0; t < cnt; t++) {
+ struct record_thread *th = threads + t;
+
+ if (i == th->mmap_nr)
+ continue;
+
+ th->mmap[i] = &evlist->mmap[j++];
+
+ if (j == nr)
+ goto out;
+ }
+ i++;
+ }
+out:
+ /* Assign track maps to thread 0. */
+ for (i = n0, j = 0; j < nr_trk && i < thread0->mmap_nr; i++, j++)
+ thread0->mmap[i] = &evlist->track_mmap[j];
+
+ return 0;
+}
+
+static int
record__threads_assign(struct record *rec)
{
if (rec->threads_all)
@@ -1146,7 +1239,7 @@ record__threads_assign(struct record *rec)
else if (rec->threads_one)
return record__threads_assign_single(rec);
else
- return -EINVAL;
+ return record__threads_assign_cnt(rec);
}

static int
@@ -1211,15 +1304,15 @@ static int record__threads_cnt(struct record *rec)

if (rec->threads_set) {
if (rec->threads_cnt) {
- pr_err("failed: Can't specify number of threads yet.\n");
- return -EINVAL;
+ cnt = rec->threads_cnt;
+ } else {
+ cnt = evlist->nr_mmaps;
+ all = true;
}
if (evlist->overwrite_mmap) {
pr_err("failed: Can't use multiple threads with overwrite mmaps yet.\n");
return -EINVAL;
}
- cnt = evlist->nr_mmaps;
- all = true;
} else {
one = true;
cnt = 1;
--
2.13.6