[PATCH 11/11] kvm tools: Use native vectored AIO in virtio-blk

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This patch hooks AIO support into virtio-blk, allowing for faster IO.

Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
---
 tools/kvm/disk/core.c              |   35 +++++++++++++++++++++++++++++++++--
 tools/kvm/disk/qcow.c              |    4 ++++
 tools/kvm/disk/raw.c               |   19 +++++++++++++++----
 tools/kvm/include/kvm/disk-image.h |    3 +++
 tools/kvm/virtio/blk.c             |   11 +++++------
 5 files changed, 60 insertions(+), 12 deletions(-)

diff --git a/tools/kvm/disk/core.c b/tools/kvm/disk/core.c
index 557a1a2..17fe548 100644
--- a/tools/kvm/disk/core.c
+++ b/tools/kvm/disk/core.c
@@ -1,8 +1,30 @@
 #include "kvm/disk-image.h"
 #include "kvm/qcow.h"
+#include "kvm/virtio-blk.h"
+
+#include <sys/eventfd.h>
+#include <sys/poll.h>
+
+#define AIO_MAX 32
 
 int debug_iodelay;
 
+static void *disk_image__thread(void *param)
+{
+	struct disk_image *disk = param;
+	u64 dummy;
+
+	while (read(disk->evt, &dummy, sizeof(dummy)) > 0) {
+		struct io_event event;
+		struct timespec notime = {0};
+
+		while (io_getevents(disk->ctx, 1, 1, &event, &notime) > 0)
+			disk->disk_req_cb(event.data, event.res);
+	}
+
+	return NULL;
+}
+
 struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops, int use_mmap)
 {
 	struct disk_image *disk;
@@ -26,6 +48,14 @@ struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operation
 		}
 	}
 
+	if (disk) {
+		pthread_t thread;
+
+		disk->evt = eventfd(0, 0);
+		io_setup(AIO_MAX, &disk->ctx);
+		if (pthread_create(&thread, NULL, disk_image__thread, disk) != 0)
+			die("Failed starting IO řthread");
+	}
 	return disk;
 }
 
@@ -87,6 +117,7 @@ struct disk_image **disk_image__open_all(const char **filenames, bool *readonly,
 			goto error;
 		}
 	}
+
 	return disks;
 error:
 	for (i = 0; i < count; i++)
@@ -151,7 +182,7 @@ ssize_t disk_image__read(struct disk_image *disk, u64 sector, const struct iovec
 		/* Do nothing */
 	}
 
-	if (disk->disk_req_cb)
+	if (!disk->async && disk->disk_req_cb)
 		disk->disk_req_cb(param, total);
 
 	return total;
@@ -182,7 +213,7 @@ ssize_t disk_image__write(struct disk_image *disk, u64 sector, const struct iove
 		/* Do nothing */
 	}
 
-	if (disk->disk_req_cb)
+	if (!disk->async && disk->disk_req_cb)
 		disk->disk_req_cb(param, total);
 
 	return total;
diff --git a/tools/kvm/disk/qcow.c b/tools/kvm/disk/qcow.c
index f9598de..87385df 100644
--- a/tools/kvm/disk/qcow.c
+++ b/tools/kvm/disk/qcow.c
@@ -1145,6 +1145,8 @@ static struct disk_image *qcow2_probe(int fd, bool readonly)
 
 	if (!disk_image)
 		goto free_refcount_table;
+
+	disk_image->async = 1;
 	disk_image->priv = q;
 
 	return disk_image;
@@ -1276,6 +1278,8 @@ static struct disk_image *qcow1_probe(int fd, bool readonly)
 
 	if (!disk_image)
 		goto free_l1_table;
+
+	disk_image->async = 1;
 	disk_image->priv = q;
 
 	return disk_image;
diff --git a/tools/kvm/disk/raw.c b/tools/kvm/disk/raw.c
index fa2e013..3612623 100644
--- a/tools/kvm/disk/raw.c
+++ b/tools/kvm/disk/raw.c
@@ -1,19 +1,25 @@
 #include "kvm/disk-image.h"
 
+#include <libaio.h>
+
 ssize_t raw_image__read_sector(struct disk_image *disk, u64 sector, const struct iovec *iov,
 				int iovcount, void *param)
 {
+	struct iocb iocb;
 	u64 offset = sector << SECTOR_SHIFT;
 
-	return preadv_in_full(disk->fd, iov, iovcount, offset);
+	return aio_preadv(disk->ctx, &iocb, disk->fd, iov, iovcount, offset,
+				disk->evt, param);
 }
 
 ssize_t raw_image__write_sector(struct disk_image *disk, u64 sector, const struct iovec *iov,
 				int iovcount, void *param)
 {
+	struct iocb iocb;
 	u64 offset = sector << SECTOR_SHIFT;
 
-	return pwritev_in_full(disk->fd, iov, iovcount, offset);
+	return aio_pwritev(disk->ctx, &iocb, disk->fd, iov, iovcount, offset,
+				disk->evt, param);
 }
 
 ssize_t raw_image__read_sector_mmap(struct disk_image *disk, u64 sector, const struct iovec *iov,
@@ -72,13 +78,13 @@ static struct disk_image_operations raw_image_regular_ops = {
 
 struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
 {
+	struct disk_image *disk;
 
 	if (readonly) {
 		/*
 		 * Use mmap's MAP_PRIVATE to implement non-persistent write
 		 * FIXME: This does not work on 32-bit host.
 		 */
-		struct disk_image *disk;
 		struct disk_image_operations ro_ops = {
 			.read_sector	= raw_image__read_sector_mmap,
 			.write_sector	= raw_image__write_sector_mmap,
@@ -90,6 +96,8 @@ struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
 			ro_ops = raw_image_regular_ops;
 			ro_ops.write_sector = NULL;
 			disk = disk_image__new(fd, st->st_size, &ro_ops, DISK_IMAGE_REGULAR);
+			if (disk)
+				disk->async = 1;
 		}
 
 		return disk;
@@ -97,6 +105,9 @@ struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
 		/*
 		 * Use read/write instead of mmap
 		 */
-		return disk_image__new(fd, st->st_size, &raw_image_regular_ops, DISK_IMAGE_REGULAR);
+		disk = disk_image__new(fd, st->st_size, &raw_image_regular_ops, DISK_IMAGE_REGULAR);
+		if (disk)
+			disk->async = 1;
+		return disk;
 	}
 }
diff --git a/tools/kvm/include/kvm/disk-image.h b/tools/kvm/include/kvm/disk-image.h
index bcb3396..5a14eab 100644
--- a/tools/kvm/include/kvm/disk-image.h
+++ b/tools/kvm/include/kvm/disk-image.h
@@ -46,6 +46,9 @@ struct disk_image {
 	void				*priv;
 	void				*disk_req_cb_param;
 	void				(*disk_req_cb)(void *param, long len);
+	bool				async;
+	int				evt;
+	io_context_t			ctx;
 };
 
 struct disk_image *disk_image__open(const char *filename, bool readonly);
diff --git a/tools/kvm/virtio/blk.c b/tools/kvm/virtio/blk.c
index c167dc9..3d31228d 100644
--- a/tools/kvm/virtio/blk.c
+++ b/tools/kvm/virtio/blk.c
@@ -2,7 +2,6 @@
 
 #include "kvm/virtio-pci-dev.h"
 #include "kvm/disk-image.h"
-#include "kvm/virtio.h"
 #include "kvm/mutex.h"
 #include "kvm/util.h"
 #include "kvm/kvm.h"
@@ -11,23 +10,23 @@
 #include "kvm/ioeventfd.h"
 #include "kvm/guest_compat.h"
 #include "kvm/virtio-pci.h"
+#include "kvm/virtio.h"
 
 #include <linux/virtio_ring.h>
 #include <linux/virtio_blk.h>
-
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/types.h>
 #include <pthread.h>
 
 #define VIRTIO_BLK_MAX_DEV		4
-#define NUM_VIRT_QUEUES			1
 
-#define VIRTIO_BLK_QUEUE_SIZE		128
 /*
  * the header and status consume too entries
  */
 #define DISK_SEG_MAX			(VIRTIO_BLK_QUEUE_SIZE - 2)
+#define VIRTIO_BLK_QUEUE_SIZE		128
+#define NUM_VIRT_QUEUES			1
 
 struct blk_dev_req {
 	struct list_head		list;
@@ -84,8 +83,8 @@ void virtio_blk_complete(void *param, long len)
 	u8 *status;
 
 	/* status */
-	status			= req->iov[req->out + req->in - 1].iov_base;
-	*status			= (len < 0) ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;
+	status	= req->iov[req->out + req->in - 1].iov_base;
+	*status	= (len < 0) ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;
 
 	mutex_lock(&bdev->mutex);
 	virt_queue__set_used_elem(req->vq, req->head, len);
-- 
1.7.7.1

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