test: add test cases for hybrid iopoll

Add a test file for hybrid iopoll to make sure it works safe.Test case
include basic read/write tests, and run in normal iopoll mode and
passthrough mode respectively.

--
changes since v1:
- remove iopoll-hybridpoll.c
- test hybrid poll with exsiting iopoll and io_uring_passthrough
- add a misconfiguration check

changes since v2:
- modify description of man doc

Signed-off-by: hexue <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

man/io_uring_setup.2

@@ -78,7 +78,15 @@ in question. For NVMe devices, the nvme driver must be loaded with the
 parameter set to the desired number of polling queues. The polling queues
 will be shared appropriately between the CPUs in the system, if the number
 is less than the number of online CPU threads.
-
+.TP
+.B IORING_SETUP_HYBRID_IOPOLL
+This flag must be used with
+.B IORING_SETUP_IOPOLL
+flag. Hybrid io polling is a feature based on iopoll, it differs from strict
+polling in that it will delay a bit before doing completion side polling, to
+avoid wasting too much CPU resources. Like
+.B IOPOLL
+, it requires that devices support polling.
 .TP
 .B IORING_SETUP_SQPOLL
 When this flag is specified, a kernel thread is created to perform

src/include/liburing/io_uring.h

@@ -200,6 +200,9 @@ enum io_uring_sqe_flags_bit {
  */
 #define IORING_SETUP_NO_SQARRAY		(1U << 16)
 
+/* Use hybrid poll in iopoll process */
+#define IORING_SETUP_HYBRID_IOPOLL      (1U << 17)
+
 enum io_uring_op {
 	IORING_OP_NOP,
 	IORING_OP_READV,

test/io_uring_passthrough.c

@@ -254,7 +254,7 @@ static int __test_io(const char *file, struct io_uring *ring, int tc, int read,
 }
 
 static int test_io(const char *file, int tc, int read, int sqthread,
-		   int fixed, int nonvec)
+		   int fixed, int nonvec, int hybrid)
 {
 	struct io_uring ring;
 	int ret, ring_flags = 0;
@@ -265,6 +265,9 @@ static int test_io(const char *file, int tc, int read, int sqthread,
 	if (sqthread)
 		ring_flags |= IORING_SETUP_SQPOLL;
 
+	if (hybrid)
+		ring_flags |= IORING_SETUP_IOPOLL | IORING_SETUP_HYBRID_IOPOLL;
+
 	ret = t_create_ring(64, &ring, ring_flags);
 	if (ret == T_SETUP_SKIP)
 		return 0;
@@ -449,18 +452,19 @@ int main(int argc, char *argv[])
 
 	vecs = t_create_buffers(BUFFERS, BS);
 
-	for (i = 0; i < 16; i++) {
+	for (i = 0; i < 32; i++) {
 		int read = (i & 1) != 0;
 		int sqthread = (i & 2) != 0;
 		int fixed = (i & 4) != 0;
 		int nonvec = (i & 8) != 0;
+		int hybrid = (i & 16) != 0;
 
-		ret = test_io(fname, i, read, sqthread, fixed, nonvec);
+		ret = test_io(fname, i, read, sqthread, fixed, nonvec, hybrid);
 		if (no_pt)
 			break;
 		if (ret) {
-			fprintf(stderr, "test_io failed %d/%d/%d/%d\n",
-				read, sqthread, fixed, nonvec);
+			fprintf(stderr, "test_io failed %d/%d/%d/%d/%d\n",
+				read, sqthread, fixed, nonvec, hybrid);
 			goto err;
 		}
 	}

test/iopoll.c

@@ -351,7 +351,7 @@ static int test_io_uring_submit_enters(const char *file)
 }
 
 static int test_io(const char *file, int write, int sqthread, int fixed,
-		   int buf_select, int defer)
+		   int hybrid, int buf_select, int defer)
 {
 	struct io_uring ring;
 	int ret, ring_flags = IORING_SETUP_IOPOLL;
@@ -363,6 +363,9 @@ static int test_io(const char *file, int write, int sqthread, int fixed,
 		ring_flags |= IORING_SETUP_SINGLE_ISSUER |
 			      IORING_SETUP_DEFER_TASKRUN;
 
+	if (hybrid)
+		ring_flags |= IORING_SETUP_HYBRID_IOPOLL;
+
 	ret = t_create_ring(64, &ring, ring_flags);
 	if (ret == T_SETUP_SKIP)
 		return 0;
@@ -418,22 +421,23 @@ int main(int argc, char *argv[])
 
 	vecs = t_create_buffers(BUFFERS, BS);
 
-	nr = 32;
+	nr = 64;
 	if (no_buf_select)
-		nr = 8;
-	else if (!t_probe_defer_taskrun())
 		nr = 16;
+	else if (!t_probe_defer_taskrun())
+		nr = 32;
 	for (i = 0; i < nr; i++) {
 		int write = (i & 1) != 0;
 		int sqthread = (i & 2) != 0;
 		int fixed = (i & 4) != 0;
-		int buf_select = (i & 8) != 0;
-		int defer = (i & 16) != 0;
+		int hybrid = (i & 8) != 0;
+		int buf_select = (i & 16) != 0;
+		int defer = (i & 32) != 0;
 
-		ret = test_io(fname, write, sqthread, fixed, buf_select, defer);
+		ret = test_io(fname, write, sqthread, fixed, hybrid, buf_select, defer);
 		if (ret) {
-			fprintf(stderr, "test_io failed %d/%d/%d/%d/%d\n",
-				write, sqthread, fixed, buf_select, defer);
+			fprintf(stderr, "test_io failed %d/%d/%d/%d/%d/%d\n",
+				write, sqthread, fixed, hybrid, buf_select, defer);
 			goto err;
 		}
 		if (no_iopoll)