[PATCH liburing 1/1] examples: add rsrc update benchmark

[Pavel Begunkov <asml.silence@gmail.com>]

Add a stupid benchmark updating files in a loop mainly for profiling
purposes and estimating the rsrc update overhead.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 examples/Makefile            |   3 +-
 examples/rsrc-update-bench.c | 100 +++++++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 examples/rsrc-update-bench.c

diff --git a/examples/Makefile b/examples/Makefile
index ce33af9..715ac4c 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -20,7 +20,8 @@ example_srcs := \
 	io_uring-udp.c \
 	link-cp.c \
 	poll-bench.c \
-	send-zerocopy.c
+	send-zerocopy.c \
+	rsrc-update-bench.c
 
 all_targets :=
 
diff --git a/examples/rsrc-update-bench.c b/examples/rsrc-update-bench.c
new file mode 100644
index 0000000..5e3cd99
--- /dev/null
+++ b/examples/rsrc-update-bench.c
@@ -0,0 +1,100 @@
+/* SPDX-License-Identifier: MIT */
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <poll.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+
+#include "liburing.h"
+
+static unsigned long runtime_ms = 10000;
+
+static unsigned long gettimeofday_ms(void)
+{
+	struct timeval tv;
+
+	gettimeofday(&tv, NULL);
+	return (tv.tv_sec * 1000) + (tv.tv_usec / 1000);
+}
+
+int main(void)
+{
+	unsigned long tstop;
+	unsigned long nr_reqs = 0;
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	struct io_uring ring;
+	int pipe1[2];
+	int ret, i, qd = 32;
+	int table_size = 128;
+
+	if (pipe(pipe1) != 0) {
+		perror("pipe");
+		return 1;
+	}
+
+	ret = io_uring_queue_init(1024, &ring, IORING_SETUP_SINGLE_ISSUER |
+					       IORING_SETUP_DEFER_TASKRUN);
+	if (ret) {
+		fprintf(stderr, "io_uring_queue_init failed: %d\n", ret);
+		return 1;
+	}
+	ret = io_uring_register_ring_fd(&ring);
+	if (ret < 0) {
+		fprintf(stderr, "io_uring_register_ring_fd failed\n");
+		return 1;
+	}
+	ret = io_uring_register_files_sparse(&ring, table_size);
+	if (ret < 0) {
+		fprintf(stderr, "io_uring_register_files_sparse failed\n");
+		return 1;
+	}
+
+	for (i = 0; i < table_size; i++) {
+		ret = io_uring_register_files_update(&ring, i, pipe1, 1);
+		if (ret < 0) {
+			fprintf(stderr, "io_uring_register_files_update failed\n");
+			return 1;
+		}
+	}
+
+	srand(time(NULL));
+
+	tstop = gettimeofday_ms() + runtime_ms;
+	do {
+		int off = rand();
+
+		for (i = 0; i < qd; i++) {
+			sqe = io_uring_get_sqe(&ring);
+			int roff = (off + i) % table_size;
+			io_uring_prep_files_update(sqe, pipe1, 1, roff);
+		}
+
+		ret = io_uring_submit(&ring);
+		if (ret != qd) {
+			fprintf(stderr, "child: sqe submit failed: %d\n", ret);
+			return 1;
+		}
+
+		for (i = 0; i < qd; i++) {
+			ret = io_uring_wait_cqe(&ring, &cqe);
+			if (ret < 0) {
+				fprintf(stderr, "child: wait completion %d\n", ret);
+				break;
+			}
+			io_uring_cqe_seen(&ring, cqe);
+			nr_reqs++;
+		}
+	} while (gettimeofday_ms() < tstop);
+
+	fprintf(stderr, "max updates/s: %lu\n", nr_reqs * 1000UL / runtime_ms);
+
+	io_uring_queue_exit(&ring);
+	close(pipe1[0]);
+	close(pipe1[1]);
+	return 0;
+}
-- 
2.39.1