On Tue, May 17, 2011 at 01:46:21PM -0700, Shirley Ma wrote:
> Hello Michael,
>
> Here is the patch I used to test out of order before: add used in a pend
> array, and swap the last two ids.
>
> I used to hit an issue, but now it seems working well.
Aha, so if I apply this guest will *not* crash? :)
> This won't impact zero-copy patch since we need to maintain the pend
> used ids anyway.
Yes, but now we can mark them used immediately as they are
completed - and I am guessing this will relieve the
pressure on tx ring that you see?
> Signed-off-by: Shirley Ma <xma@xxxxxxxxxx>
> ---
> drivers/vhost/net.c | 24 +++++++++++++++++++++++-
> drivers/vhost/vhost.c | 11 +++++++++++
> drivers/vhost/vhost.h | 1 +
> 3 files changed, 35 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 2f7c76a..19e1baa 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -32,6 +32,8 @@
> * Using this limit prevents one virtqueue from starving others. */
> #define VHOST_NET_WEIGHT 0x80000
>
> +#define VHOST_MAX_PEND 128
> +
> enum {
> VHOST_NET_VQ_RX = 0,
> VHOST_NET_VQ_TX = 1,
> @@ -198,13 +200,33 @@ static void handle_tx(struct vhost_net *net)
> if (err != len)
> pr_debug("Truncated TX packet: "
> " len %d != %zd\n", err, len);
> - vhost_add_used_and_signal(&net->dev, vq, head, 0);
> + vq->heads[vq->pend_idx].id = head;
> + vq->heads[vq->pend_idx].len = 0;
> + ++vq->pend_idx;
> + if (vq->pend_idx >= VHOST_MAX_PEND) {
> + int id;
> + id = vq->heads[vq->pend_idx-1].id;
> + vq->heads[vq->pend_idx-1].id = vq->heads[vq->pend_idx-2].id;
> + vq->heads[vq->pend_idx-2].id = id;
> + vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
> + vq->pend_idx);
> + vq->pend_idx = 0;
> + }
> total_len += len;
> if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
> vhost_poll_queue(&vq->poll);
> break;
> }
> }
> + if (vq->pend_idx >= VHOST_MAX_PEND) {
> + int id;
> + id = vq->heads[vq->pend_idx-1].id;
> + vq->heads[vq->pend_idx-1].id = vq->heads[vq->pend_idx-2].id;
> + vq->heads[vq->pend_idx-2].id = id;
> + vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
> + vq->pend_idx);
> + vq->pend_idx = 0;
> + }
>
> mutex_unlock(&vq->mutex);
> }
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 2ab2912..7eea6b3 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -174,6 +174,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
> vq->call_ctx = NULL;
> vq->call = NULL;
> vq->log_ctx = NULL;
> + vq->pend_idx = 0;
> }
>
> static int vhost_worker(void *data)
> @@ -395,6 +396,11 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
> vhost_poll_stop(&dev->vqs[i].poll);
> vhost_poll_flush(&dev->vqs[i].poll);
> }
> + if (dev->vqs[i].pend_idx != 0) {
> + vhost_add_used_and_signal_n(dev, &dev->vqs[i],
> + dev->vqs[i].heads, dev->vqs[i].pend_idx);
> + dev->vqs[i].pend_idx = 0;
> + }
> if (dev->vqs[i].error_ctx)
> eventfd_ctx_put(dev->vqs[i].error_ctx);
> if (dev->vqs[i].error)
> @@ -603,6 +609,11 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
>
> mutex_lock(&vq->mutex);
>
> + if (vq->pend_idx != 0) {
> + vhost_add_used_and_signal_n(d, vq, vq->heads, vq->pend_idx);
> + vq->pend_idx = 0;
> + }
> +
> switch (ioctl) {
> case VHOST_SET_VRING_NUM:
> /* Resizing ring with an active backend?
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index b3363ae..44a412d 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -108,6 +108,7 @@ struct vhost_virtqueue {
> /* Log write descriptors */
> void __user *log_base;
> struct vhost_log *log;
> + int pend_idx;
> };
>
> struct vhost_dev {
>
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