On 8/28/19 4:49 PM, Eelco Chaudron wrote:
> This patch adds an operation callback which gets called every time
> the library is waking up the guest trough an eventfd_write() call.
>
> This can be used by 3rd party application, like OVS, to track the
> number of times interrupts where generated. This might be of
> interest to find out system-call were called in the fast path.
>
> Signed-off-by: Eelco Chaudron <echau...@redhat.com>
> ---
> lib/librte_vhost/rte_vhost.h | 10 +++++++++-
> lib/librte_vhost/vhost.h | 15 ++++++++++++---
> 2 files changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
> index 7fb1729..878e339 100644
> --- a/lib/librte_vhost/rte_vhost.h
> +++ b/lib/librte_vhost/rte_vhost.h
> @@ -172,7 +172,15 @@ struct vhost_device_ops {
> int (*new_connection)(int vid);
> void (*destroy_connection)(int vid);
>
> - void *reserved[2]; /**< Reserved for future extension */
> + /**
> + * This callback gets called each time a guest gets notified
> + * about waiting packets. This is the interrupt handling trough
> + * the eventfd_write(callfd), which can be used for counting these
> + * "slow" syscalls.
> + */
> + void (*guest_notified)(int vid);
> +
> + void *reserved[1]; /**< Reserved for future extension */
> };
>
> /**
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 884befa..5131a97 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -543,13 +543,19 @@ void *vhost_alloc_copy_ind_table(struct virtio_net *dev,
>
> if ((vhost_need_event(vhost_used_event(vq), new, old) &&
> (vq->callfd >= 0)) ||
> - unlikely(!signalled_used_valid))
> + unlikely(!signalled_used_valid)) {
> eventfd_write(vq->callfd, (eventfd_t) 1);
> + if (dev->notify_ops->guest_notified)
> + dev->notify_ops->guest_notified(dev->vid);
> + }
> } else {
> /* Kick the guest if necessary. */
> if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
> - && (vq->callfd >= 0))
> + && (vq->callfd >= 0)) {
> eventfd_write(vq->callfd, (eventfd_t)1);
> + if (dev->notify_ops->guest_notified)
> + dev->notify_ops->guest_notified(dev->vid);
> + }
> }
> }
>
> @@ -600,8 +606,11 @@ void *vhost_alloc_copy_ind_table(struct virtio_net *dev,
> if (vhost_need_event(off, new, old))
> kick = true;
> kick:
> - if (kick)
> + if (kick) {
> eventfd_write(vq->callfd, (eventfd_t)1);
> + if (dev->notify_ops->guest_notified)
> + dev->notify_ops->guest_notified(dev->vid);
> + }
> }
>
> static __rte_always_inline void
>
Applied to dpdk-next-virtio/master.
Thanks,
Maxime
