From 8c82c2be9fe2b3a66d6f3729832fb9fd40e03070 Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Sat, 2 Jul 2011 19:52:04 -0400 Subject: [PATCH] kvm tools: Process virtio-blk requests in parallel 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 Signed-off-by: Sasha Levin Signed-off-by: Pekka Enberg --- tools/kvm/virtio/blk.c | 74 ++++++++++++++++++++++-------------------- 1 file changed, 38 insertions(+), 36 deletions(-) diff --git a/tools/kvm/virtio/blk.c b/tools/kvm/virtio/blk.c index 1fdfc1e57d08..f2a728c85624 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), }; -- 2.39.5