[liburing,v2] test: add test cases for hybrid iopoll

Commit Message

hexue Nov. 14, 2024, 5:03 a.m. UTC

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

Signed-off-by: hexue <[e-mail]>
---
 man/io_uring_setup.2            | 10 +++++++++-
 src/include/liburing/io_uring.h |  3 +++
 src/setup.c                     |  4 ++++
 test/io_uring_passthrough.c     | 14 +++++++++-----
 test/iopoll.c                   | 22 +++++++++++++---------
 5 files changed, 38 insertions(+), 15 deletions(-)

Comments

Jens Axboe Nov. 14, 2024, 3:21 p.m. UTC | #1

On 11/13/24 10:03 PM, hexue wrote:
> diff --git a/man/io_uring_setup.2 b/man/io_uring_setup.2
> index 2f87783..fa928fa 100644
> --- a/man/io_uring_setup.2
> +++ b/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 setup with

This flag must be used with

> +.B IORING_SETUP_IOPOLL
> +flag. hybrid poll is a new

Like before, skip new. Think about what happens when someone reads this
in 5 years time. What does new mean? Yes it may be new now, but docs
are supposed to be timeless.

> +feature baed on iopoll, this could be a suboptimal solution when running

based on

> +on a single thread, it offers higher performance than IRQ and lower CPU
> +utilization than polling. Similarly, this feature also requires the devices
> +to support polling configuration.

This doesn't explain how it works. I'd say something like:

Hybrid io polling differs from strict polling in that it will delay a
bit before doing completion side polling, to avoid wasting too much CPU.
Like IOPOLL, it requires that devices support polling.


> diff --git a/src/setup.c b/src/setup.c
> index 073de50..d1a87aa 100644
> --- a/src/setup.c
> +++ b/src/setup.c
> @@ -320,6 +320,10 @@ int __io_uring_queue_init_params(unsigned entries, struct io_uring *ring,
>  			ring->int_flags |= INT_FLAG_APP_MEM;
>  	}
>  
> +	if ((p->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_HYBRID_IOPOLL)) ==
> +			IORING_SETUP_HYBRID_IOPOLL)
> +		return -EINVAL;
> +

The kernel should already do this, no point duplicating it in liburing.

The test bits look much better now, way simpler. I'll just need to
double check that they handle EINVAL on setup properly, and EOPNOTSUPP
at completion time will turn off further testing of it. Did you run it
on configurations where hybrid io polling will both fail at setup time,
and at runtime (eg the latter where the kernel supports it, but the
device/fs does not)?

Patch

diff --git a/man/io_uring_setup.2 b/man/io_uring_setup.2
index 2f87783..fa928fa 100644
--- a/man/io_uring_setup.2
+++ b/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 setup with
+.B IORING_SETUP_IOPOLL
+flag. hybrid poll is a new
+feature baed on iopoll, this could be a suboptimal solution when running
+on a single thread, it offers higher performance than IRQ and lower CPU
+utilization than polling. Similarly, this feature also requires the devices
+to support polling configuration.
 .TP
 .B IORING_SETUP_SQPOLL
 When this flag is specified, a kernel thread is created to perform
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index 20bc570..d16364c 100644
--- a/src/include/liburing/io_uring.h
+++ b/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,
diff --git a/src/setup.c b/src/setup.c
index 073de50..d1a87aa 100644
--- a/src/setup.c
+++ b/src/setup.c
@@ -320,6 +320,10 @@  int __io_uring_queue_init_params(unsigned entries, struct io_uring *ring,
 			ring->int_flags |= INT_FLAG_APP_MEM;
 	}
 
+	if ((p->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_HYBRID_IOPOLL)) ==
+			IORING_SETUP_HYBRID_IOPOLL)
+		return -EINVAL;
+
 	fd = __sys_io_uring_setup(entries, p);
 	if (fd < 0) {
 		if ((p->flags & IORING_SETUP_NO_MMAP) &&
diff --git a/test/io_uring_passthrough.c b/test/io_uring_passthrough.c
index f18a186..8604c42 100644
--- a/test/io_uring_passthrough.c
+++ b/test/io_uring_passthrough.c
@@ -254,7 +254,7 @@  err:
 }
 
 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;
 		}
 	}
diff --git a/test/iopoll.c b/test/iopoll.c
index 2e0f7ea..0d7bd77 100644
--- a/test/iopoll.c
+++ b/test/iopoll.c
@@ -351,7 +351,7 @@  ok:
 }
 
 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)