On Fri, Nov 25, 2011 at 5:47 PM, Asias He <asias.he...@gmail.com> wrote:
> This patch also fixes fio seq-read hang problem.
>
> root@guest-kvm:~# cat seq-read.fio
> [seq-read]
> rw=read
> bs=4096
> size=512m
> direct=1
> filename=/dev/vdb
>
> root@guest-kvm:~# fio seq-read.fio
> random-read: (g=0): rw=read, bs=4K-4K/4K-4K, ioengine=sync, iodepth=1
> Starting 1 process
> Jobs: 1 (f=1): [R] [50.0% done] [0K/0K /s] [0/0 iops] [eta 00m:27s]
>
> Signed-off-by: Asias He <asias.he...@gmail.com>
Sasha, does this look good to you?
> ---
> tools/kvm/include/kvm/virtio.h | 6 ++----
> tools/kvm/virtio/core.c | 16 ++++++++++++++++
> 2 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/tools/kvm/include/kvm/virtio.h b/tools/kvm/include/kvm/virtio.h
> index cd24285..d117bfc 100644
> --- a/tools/kvm/include/kvm/virtio.h
> +++ b/tools/kvm/include/kvm/virtio.h
> @@ -22,6 +22,7 @@ struct virt_queue {
> /* The last_avail_idx field is an index to ->ring of struct
> vring_avail.
> It's where we assume the next request index is at. */
> u16 last_avail_idx;
> + u16 last_used_signalled;
> };
>
> static inline u16 virt_queue__pop(struct virt_queue *queue)
> @@ -53,13 +54,10 @@ static inline void *guest_pfn_to_host(struct kvm *kvm,
> u32 pfn)
> return guest_flat_to_host(kvm, (unsigned long)pfn <<
> VIRTIO_PCI_QUEUE_ADDR_SHIFT);
> }
>
> -static inline int virtio_queue__should_signal(struct virt_queue *vq)
> -{
> - return vring_used_event(&vq->vring) <= vq->vring.used->idx;
> -}
>
> struct vring_used_elem *virt_queue__set_used_elem(struct virt_queue *queue,
> u32 head, u32 len);
>
> +bool virtio_queue__should_signal(struct virt_queue *vq);
> u16 virt_queue__get_iov(struct virt_queue *queue, struct iovec iov[], u16
> *out, u16 *in, struct kvm *kvm);
> u16 virt_queue__get_inout_iov(struct kvm *kvm, struct virt_queue *queue,
> struct iovec in_iov[], struct iovec out_iov[],
> diff --git a/tools/kvm/virtio/core.c b/tools/kvm/virtio/core.c
> index 0466e07..8032d7a 100644
> --- a/tools/kvm/virtio/core.c
> +++ b/tools/kvm/virtio/core.c
> @@ -109,3 +109,19 @@ int virtio__get_dev_specific_field(int offset, bool
> msix, bool features_hi, u32
>
> return VIRTIO_PCI_O_CONFIG;
> }
> +
> +bool virtio_queue__should_signal(struct virt_queue *vq)
> +{
> + u16 old_idx, new_idx, event_idx;
> +
> + old_idx = vq->last_used_signalled;
> + new_idx = vq->vring.used->idx;
> + event_idx = vring_used_event(&vq->vring);
> +
> + if (vring_need_event(event_idx, new_idx, old_idx)) {
> + vq->last_used_signalled = new_idx;
> + return true;
> + }
> +
> + return false;
> +}
> --
> 1.7.7.3
>
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