Process multiple requests within a virtio-blk device's vring
in parallel.
Doing so may improve performance in cases when a request which can
be completed using data which is present in a cache is queued after
a request with un-cached data.
bonnie++ benchmarks have shown a 6% improvement with reads, and 2%
improvement in writes.
Suggested-by: Anthony Liguori <aliguori@xxxxxxxxxx>
Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
---
tools/kvm/virtio/blk.c | 74 ++++++++++++++++++++++++-----------------------
1 files changed, 38 insertions(+), 36 deletions(-)
diff --git a/tools/kvm/virtio/blk.c b/tools/kvm/virtio/blk.c
index 1fdfc1e..f2a728c 100644
--- a/tools/kvm/virtio/blk.c
+++ b/tools/kvm/virtio/blk.c
@@ -31,6 +31,8 @@
struct blk_dev_job {
struct virt_queue *vq;
struct blk_dev *bdev;
+ struct iovec iov[VIRTIO_BLK_QUEUE_SIZE];
+ u16 out, in, head;
struct thread_pool__job job_id;
};
@@ -51,7 +53,8 @@ struct blk_dev {
u16 queue_selector;
struct virt_queue vqs[NUM_VIRT_QUEUES];
- struct blk_dev_job jobs[NUM_VIRT_QUEUES];
+ struct blk_dev_job jobs[VIRTIO_BLK_QUEUE_SIZE];
+ u16 job_idx;
struct pci_device_header pci_hdr;
};
@@ -118,20 +121,26 @@ static bool virtio_blk_pci_io_in(struct ioport *ioport, struct kvm *kvm, u16 por
return ret;
}
-static bool virtio_blk_do_io_request(struct kvm *kvm,
- struct blk_dev *bdev,
- struct virt_queue *queue)
+static void virtio_blk_do_io_request(struct kvm *kvm, void *param)
{
- struct iovec iov[VIRTIO_BLK_QUEUE_SIZE];
struct virtio_blk_outhdr *req;
- ssize_t block_cnt = -1;
- u16 out, in, head;
u8 *status;
+ ssize_t block_cnt;
+ struct blk_dev_job *job;
+ struct blk_dev *bdev;
+ struct virt_queue *queue;
+ struct iovec *iov;
+ u16 out, in, head;
- head = virt_queue__get_iov(queue, iov, &out, &in, kvm);
-
- /* head */
- req = iov[0].iov_base;
+ block_cnt = -1;
+ job = param;
+ bdev = job->bdev;
+ queue = job->vq;
+ iov = job->iov;
+ out = job->out;
+ in = job->in;
+ head = job->head;
+ req = iov[0].iov_base;
switch (req->type) {
case VIRTIO_BLK_T_IN:
@@ -153,24 +162,27 @@ static bool virtio_blk_do_io_request(struct kvm *kvm,
status = iov[out + in - 1].iov_base;
*status = (block_cnt < 0) ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;
+ mutex_lock(&bdev->mutex);
virt_queue__set_used_elem(queue, head, block_cnt);
+ mutex_unlock(&bdev->mutex);
- return true;
+ virt_queue__trigger_irq(queue, bdev->pci_hdr.irq_line, &bdev->isr, kvm);
}
-static void virtio_blk_do_io(struct kvm *kvm, void *param)
+static void virtio_blk_do_io(struct kvm *kvm, struct virt_queue *vq, struct blk_dev *bdev)
{
- struct blk_dev_job *job = param;
- struct virt_queue *vq;
- struct blk_dev *bdev;
+ while (virt_queue__available(vq)) {
+ struct blk_dev_job *job = &bdev->jobs[bdev->job_idx++ % VIRTIO_BLK_QUEUE_SIZE];
- vq = job->vq;
- bdev = job->bdev;
-
- while (virt_queue__available(vq))
- virtio_blk_do_io_request(kvm, bdev, vq);
+ *job = (struct blk_dev_job) {
+ .vq = vq,
+ .bdev = bdev,
+ };
+ job->head = virt_queue__get_iov(vq, job->iov, &job->out, &job->in, kvm);
- virt_queue__trigger_irq(vq, bdev->pci_hdr.irq_line, &bdev->isr, kvm);
+ thread_pool__init_job(&job->job_id, kvm, virtio_blk_do_io_request, job);
+ thread_pool__do_job(&job->job_id);
+ }
}
static bool virtio_blk_pci_io_out(struct ioport *ioport, struct kvm *kvm, u16 port, void *data, int size, u32 count)
@@ -190,24 +202,14 @@ static bool virtio_blk_pci_io_out(struct ioport *ioport, struct kvm *kvm, u16 po
break;
case VIRTIO_PCI_QUEUE_PFN: {
struct virt_queue *queue;
- struct blk_dev_job *job;
void *p;
- job = &bdev->jobs[bdev->queue_selector];
-
queue = &bdev->vqs[bdev->queue_selector];
queue->pfn = ioport__read32(data);
p = guest_pfn_to_host(kvm, queue->pfn);
vring_init(&queue->vring, VIRTIO_BLK_QUEUE_SIZE, p, VIRTIO_PCI_VRING_ALIGN);
- *job = (struct blk_dev_job) {
- .vq = queue,
- .bdev = bdev,
- };
-
- thread_pool__init_job(&job->job_id, kvm, virtio_blk_do_io, job);
-
break;
}
case VIRTIO_PCI_QUEUE_SEL:
@@ -217,7 +219,7 @@ static bool virtio_blk_pci_io_out(struct ioport *ioport, struct kvm *kvm, u16 po
u16 queue_index;
queue_index = ioport__read16(data);
- thread_pool__do_job(&bdev->jobs[queue_index].job_id);
+ virtio_blk_do_io(kvm, &bdev->vqs[queue_index], bdev);
break;
}
@@ -246,9 +248,9 @@ static struct ioport_operations virtio_blk_io_ops = {
static void ioevent_callback(struct kvm *kvm, void *param)
{
- struct blk_dev_job *job = param;
+ struct blk_dev *bdev = param;
- thread_pool__do_job(&job->job_id);
+ virtio_blk_do_io(kvm, &bdev->vqs[0], bdev);
}
void virtio_blk__init(struct kvm *kvm, struct disk_image *disk)
@@ -309,7 +311,7 @@ void virtio_blk__init(struct kvm *kvm, struct disk_image *disk)
.io_len = sizeof(u16),
.fn = ioevent_callback,
.datamatch = i,
- .fn_ptr = &bdev->jobs[i],
+ .fn_ptr = bdev,
.fn_kvm = kvm,
.fd = eventfd(0, 0),
};
--
1.7.6
--
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