The test program run result:
$ ./test_maps
...
measure_lookup: max_entries 1000000, batch 10, time 342
measure_lookup: max_entries 1000000, batch 1000, time 295
measure_lookup: max_entries 1000000, batch 1000000, time 270
measure_lookup: max_entries 1000000, no batching, time 1346
measure_lookup_delete: max_entries 1000000, batch 10, time 433
measure_lookup_delete: max_entries 1000000, batch 1000, time 363
measure_lookup_delete: max_entries 1000000, batch 1000000, time 357
measure_lookup_delete: max_entries 1000000, not batch, time 1894
measure_delete: max_entries 1000000, batch, time 220
measure_delete: max_entries 1000000, not batch, time 1289
test_map_batch_perf:PASS
...
The test is running on a qemu VM environment. The time
unit is millisecond. A simple hash table with 1M elements
is created.
For lookup and lookup_and_deletion, since buffer allocation
is needed to hold the lookup results, three different
batch sizes (10, 1000, and 1M) are tried. The performance
without batching is also measured. A batch size of 10
can already improves performance dramatically, more than 70%,
and increasing batch size may continue to improve performance,
but with diminishing returns.
For delete, the batch API provides a mechanism to delete all elements
in the map, which is used here. The deletion of the whole map
improves performance by 80% compared to non-batch mechanism.
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
.../selftests/bpf/map_tests/map_batch_perf.c | 242 ++++++++++++++++++
1 file changed, 242 insertions(+)
create mode 100644 tools/testing/selftests/bpf/map_tests/map_batch_perf.c
diff --git a/tools/testing/selftests/bpf/map_tests/map_batch_perf.c b/tools/testing/selftests/bpf/map_tests/map_batch_perf.c
new file mode 100644
index 000000000000..42d95651e1ac
--- /dev/null
+++ b/tools/testing/selftests/bpf/map_tests/map_batch_perf.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook */
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include <test_maps.h>
+
+/* Test map batch performance.
+ * Test three common scenarios:
+ * - batched lookup
+ * - batched lookup and delete
+ * - batched deletion
+ */
+static void map_batch_update(int map_fd, __u32 max_entries, int *keys,
+ int *values)
+{
+ int i, err;
+
+ for (i = 0; i < max_entries; i++) {
+ keys[i] = i + 1;
+ values[i] = i + 2;
+ }
+
+ err = bpf_map_update_batch(map_fd, keys, values, &max_entries, 0, 0);
+ CHECK(err, "bpf_map_update_batch()", "error:%s\n", strerror(errno));
+}
+
+static unsigned long util_gettime(void)
+{
+ struct timeval tv;
+
+ gettimeofday(&tv, NULL);
+ return (tv.tv_sec * 1000) + (tv.tv_usec / 1000);
+}
+
+static void measure_lookup(int map_fd, __u32 max_entries, int *keys,
+ int *values)
+{
+ __u32 batches[3] = {10, 1000};
+ int err, key, value, option;
+ unsigned long start, end;
+ void *p_key, *p_next_key;
+ __u32 count, total;
+
+ map_batch_update(map_fd, max_entries, keys, values);
+
+ /* batched */
+ batches[2] = max_entries;
+ for (option = 0; option < 3; option++) {
+ p_key = NULL;
+ p_next_key = &key;
+ count = batches[option];
+ start = util_gettime();
+ total = 0;
+
+ while (true) {
+ err = bpf_map_lookup_batch(map_fd, p_key, &p_next_key,
+ keys, values, &count, 0, 0);
+ CHECK(err, "bpf_map_lookup_batch()", "error: %s\n",
+ strerror(errno));
+
+ total += count;
+ if (!p_next_key)
+ break;
+
+ if (!p_key)
+ p_key = p_next_key;
+ }
+
+ end = util_gettime();
+ CHECK(total != max_entries,
+ "checking total", "total %u, max_entries %u\n",
+ total, max_entries);
+ printf("%s: max_entries %u, batch %u, time %ld\n", __func__,
+ max_entries, batches[option], end - start);
+ }
+
+ /* not batched */
+ start = util_gettime();
+ p_key = NULL;
+ p_next_key = &key;
+ while (!bpf_map_get_next_key(map_fd, p_key, p_next_key)) {
+ err = bpf_map_lookup_elem(map_fd, p_next_key, &value);
+ CHECK(err, "bpf_map_lookup_elem()", "error: %s\n",
+ strerror(errno));
+ p_key = p_next_key;
+ }
+ end = util_gettime();
+ printf("%s: max_entries %u, no batching, time %ld\n", __func__,
+ max_entries, end - start);
+}
+
+static void measure_lookup_delete(int map_fd, __u32 max_entries, int *keys,
+ int *values)
+{
+ int err, key, next_key, value, option;
+ __u32 batches[3] = {10, 1000};
+ unsigned long start, end;
+ void *p_key, *p_next_key;
+ __u32 count, total;
+
+ /* batched */
+ batches[2] = max_entries;
+ for (option = 0; option < 3; option++) {
+ map_batch_update(map_fd, max_entries, keys, values);
+ p_key = NULL;
+ p_next_key = &key;
+ count = batches[option];
+ start = util_gettime();
+ total = 0;
+
+ while (true) {
+ err = bpf_map_lookup_and_delete_batch(map_fd, p_key,
+ &p_next_key, keys, values, &count, 0, 0);
+ CHECK(err, "bpf_map_lookup_and_delete_batch()",
+ "error: %s\n", strerror(errno));
+
+ total += count;
+ if (!p_next_key)
+ break;
+
+ if (!p_key)
+ p_key = p_next_key;
+ }
+
+ end = util_gettime();
+ CHECK(total != max_entries,
+ "checking total", "total %u, max_entries %u\n",
+ total, max_entries);
+ printf("%s: max_entries %u, batch %u, time %ld\n", __func__,
+ max_entries, batches[option], end - start);
+ }
+
+ /* not batched */
+ map_batch_update(map_fd, max_entries, keys, values);
+ start = util_gettime();
+ p_key = NULL;
+ p_next_key = &key;
+ err = bpf_map_get_next_key(map_fd, p_key, p_next_key);
+ CHECK(err, "bpf_map_get_next_key()", "error: %s\n", strerror(errno));
+ err = bpf_map_lookup_elem(map_fd, p_next_key, &value);
+ CHECK(err, "bpf_map_lookup_elem()", "error: %s\n", strerror(errno));
+
+ p_key = p_next_key;
+ p_next_key = &next_key;
+ while (!bpf_map_get_next_key(map_fd, p_key, p_next_key)) {
+ err = bpf_map_delete_elem(map_fd, p_key);
+ CHECK(err, "bpf_map_delete_elem()", "error: %s\n",
+ strerror(errno));
+
+ err = bpf_map_lookup_elem(map_fd, p_next_key, &value);
+ CHECK(err, "bpf_map_lookup_elem()", "error: %s\n",
+ strerror(errno));
+
+ p_key = p_next_key;
+ p_next_key = (p_next_key == &key) ? &next_key : &key;
+ }
+ err = bpf_map_delete_elem(map_fd, p_key);
+ CHECK(err, "bpf_map_delete_elem()", "error: %s\n",
+ strerror(errno));
+ end = util_gettime();
+ printf("%s: max_entries %u, not batch, time %ld\n", __func__,
+ max_entries, end - start);
+}
+
+static void measure_delete(int map_fd, __u32 max_entries, int *keys,
+ int *values)
+{
+ unsigned long start, end;
+ void *p_key, *p_next_key;
+ int err, key, next_key;
+ __u32 count;
+
+ /* batched */
+ map_batch_update(map_fd, max_entries, keys, values);
+ count = 0;
+ p_next_key = &key;
+ start = util_gettime();
+ err = bpf_map_delete_batch(map_fd, NULL, NULL, NULL, &count, 0, 0);
+ end = util_gettime();
+ CHECK(err, "bpf_map_delete_batch()", "error: %s\n", strerror(errno));
+ CHECK(count != max_entries, "bpf_map_delete_batch()",
+ "count = %u, max_entries = %u\n", count, max_entries);
+
+ printf("%s: max_entries %u, batch, time %ld\n", __func__,
+ max_entries, end - start);
+
+ map_batch_update(map_fd, max_entries, keys, values);
+ p_key = NULL;
+ p_next_key = &key;
+ start = util_gettime();
+ err = bpf_map_get_next_key(map_fd, p_key, p_next_key);
+ CHECK(err, "bpf_map_get_next_key()", "error: %s\n", strerror(errno));
+
+ p_key = p_next_key;
+ p_next_key = &next_key;
+ while (!bpf_map_get_next_key(map_fd, p_key, p_next_key)) {
+ err = bpf_map_delete_elem(map_fd, p_key);
+ CHECK(err, "bpf_map_delete_elem()", "error: %s\n",
+ strerror(errno));
+ p_key = p_next_key;
+ p_next_key = (p_next_key == &key) ? &next_key : &key;
+ }
+ err = bpf_map_delete_elem(map_fd, p_key);
+ CHECK(err, "bpf_map_delete_elem()", "error: %s\n",
+ strerror(errno));
+ end = util_gettime();
+ printf("%s: max_entries %u, not batch, time %ld\n", __func__,
+ max_entries, end - start);
+}
+
+void test_map_batch_perf(void)
+{
+ struct bpf_create_map_attr xattr = {
+ .name = "hash_map",
+ .map_type = BPF_MAP_TYPE_HASH,
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ };
+ const __u32 max_entries = 1000000; // 1M entries for the hash table
+ int map_fd, *keys, *values;
+
+ xattr.max_entries = max_entries;
+ map_fd = bpf_create_map_xattr(&xattr);
+ CHECK(map_fd == -1,
+ "bpf_create_map_xattr()", "error:%s\n", strerror(errno));
+
+ keys = malloc(max_entries * sizeof(int));
+ values = malloc(max_entries * sizeof(int));
+ CHECK(!keys || !values, "malloc()", "error:%s\n", strerror(errno));
+
+ measure_lookup(map_fd, max_entries, keys, values);
+ measure_lookup_delete(map_fd, max_entries, keys, values);
+ measure_delete(map_fd, max_entries, keys, values);
+
+ printf("%s:PASS\n", __func__);
+}
--
2.17.1
