search for: vring_need_event

.../* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ -/* Assuming a given event_idx value from the other size, if +/* Assuming a given event_idx value from the other side, if * we have just incremented index from old to new_idx, * should we trigger an event? */ static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) -- 2.1.0

.../* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ -/* Assuming a given event_idx value from the other size, if +/* Assuming a given event_idx value from the other side, if * we have just incremented index from old to new_idx, * should we trigger an event? */ static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) -- 2.1.0

...with USED_EVENT_IDX and AVAIL_EVENT_IDX */ > -/* Assuming a given event_idx value from the other size, if > +/* Assuming a given event_idx value from the other side, if > * we have just incremented index from old to new_idx, > * should we trigger an event? */ > static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) > -- > 2.1.0

...VAIL_EVENT_IDX */ > > -/* Assuming a given event_idx value from the other size, if > > +/* Assuming a given event_idx value from the other side, if > > * we have just incremented index from old to new_idx, > > * should we trigger an event? */ > > static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) > > -- > > 2.1.0

...VAIL_EVENT_IDX */ > > -/* Assuming a given event_idx value from the other size, if > > +/* Assuming a given event_idx value from the other side, if > > * we have just incremented index from old to new_idx, > > * should we trigger an event? */ > > static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) > > -- > > 2.1.0

...truct vhost_dev *dev, struct vhost_virtqueue *vq) if (unlikely(!v)) return true; - /* We're sure if the following conditions are met, there's no - * need to notify guest: - * 1) cached used event is ahead of new - * 2) old to new updating does not cross cached used event. */ - if (vring_need_event(vq->last_used_event, new + vq->num, new) && - !vring_need_event(vq->last_used_event, new, old)) - return false; - - /* Flush out used index updates. This is paired - * with the barrier that the Guest executes when enabling - * interrupts. */ - smp_mb(); - if (vhost_get_ava...

...truct vhost_dev *dev, struct vhost_virtqueue *vq) if (unlikely(!v)) return true; - /* We're sure if the following conditions are met, there's no - * need to notify guest: - * 1) cached used event is ahead of new - * 2) old to new updating does not cross cached used event. */ - if (vring_need_event(vq->last_used_event, new + vq->num, new) && - !vring_need_event(vq->last_used_event, new, old)) - return false; - - /* Flush out used index updates. This is paired - * with the barrier that the Guest executes when enabling - * interrupts. */ - smp_mb(); - if (vhost_get_ava...

...truct vhost_dev *dev, struct vhost_virtqueue *vq) if (unlikely(!v)) return true; - /* We're sure if the following conditions are met, there's no - * need to notify guest: - * 1) cached used event is ahead of new - * 2) old to new updating does not cross cached used event. */ - if (vring_need_event(vq->last_used_event, new + vq->num, new) && - !vring_need_event(vq->last_used_event, new, old)) - return false; - - /* Flush out used index updates. This is paired - * with the barrier that the Guest executes when enabling - * interrupts. */ - smp_mb(); - if (vhost_get_ava...

...truct vhost_dev *dev, struct vhost_virtqueue *vq) if (unlikely(!v)) return true; - /* We're sure if the following conditions are met, there's no - * need to notify guest: - * 1) cached used event is ahead of new - * 2) old to new updating does not cross cached used event. */ - if (vring_need_event(vq->last_used_event, new + vq->num, new) && - !vring_need_event(vq->last_used_event, new, old)) - return false; - - /* Flush out used index updates. This is paired - * with the barrier that the Guest executes when enabling - * interrupts. */ - smp_mb(); - if (vhost_get_ava...

...; > > vq->last_add_time_valid = false; > > > > > > > #endif > > > > > > > - needs_kick = (flags != VRING_EVENT_F_DISABLE); > > > > > > > + if (flags == VRING_EVENT_F_DESC) > > > > > > > + needs_kick = vring_need_event(off_wrap & ~(1<<15), new, old); > > > > > > > > > > > > I wonder whether or not the math is correct. Both new and event are in the > > > > > > unit of descriptor ring size, but old looks not. > > > > > > > > &...

...; > > vq->last_add_time_valid = false; > > > > > > > #endif > > > > > > > - needs_kick = (flags != VRING_EVENT_F_DISABLE); > > > > > > > + if (flags == VRING_EVENT_F_DESC) > > > > > > > + needs_kick = vring_need_event(off_wrap & ~(1<<15), new, old); > > > > > > > > > > > > I wonder whether or not the math is correct. Both new and event are in the > > > > > > unit of descriptor ring size, but old looks not. > > > > > > > > &...

...ked(struct virtqueue *_vq) > > > > > vq->last_add_time_valid = false; > > > > > #endif > > > > > - needs_kick = (flags != VRING_EVENT_F_DISABLE); > > > > > + if (flags == VRING_EVENT_F_DESC) > > > > > + needs_kick = vring_need_event(off_wrap & ~(1<<15), new, old); > > > > > > > > I wonder whether or not the math is correct. Both new and event are in the > > > > unit of descriptor ring size, but old looks not. > > > > > > What vring_need_event() cares is the dist...

...ked(struct virtqueue *_vq) > > > > > vq->last_add_time_valid = false; > > > > > #endif > > > > > - needs_kick = (flags != VRING_EVENT_F_DISABLE); > > > > > + if (flags == VRING_EVENT_F_DESC) > > > > > + needs_kick = vring_need_event(off_wrap & ~(1<<15), new, old); > > > > > > > > I wonder whether or not the math is correct. Both new and event are in the > > > > unit of descriptor ring size, but old looks not. > > > > > > What vring_need_event() cares is the dist...

...io_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -567,14 +567,32 @@ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) * entry. Always do both to keep code simple. */ vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; /* Make sure used event never go backwards */ - if (!vring_need_event(vring_used_event(&vq->vring), - vq->vring.avail->idx, last_used_idx)) + if (vq->vring.avail->idx != vring_used_event(&vq->vring) && + !vring_need_event(vring_used_event(&vq->vring), + vq->vring.avail->idx, last_used_idx)) { vring...

...io_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -567,14 +567,32 @@ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) * entry. Always do both to keep code simple. */ vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; /* Make sure used event never go backwards */ - if (!vring_need_event(vring_used_event(&vq->vring), - vq->vring.avail->idx, last_used_idx)) + if (vq->vring.avail->idx != vring_used_event(&vq->vring) && + !vring_need_event(vring_used_event(&vq->vring), + vq->vring.avail->idx, last_used_idx)) { vring...

...>> @@ -567,14 +567,32 @@ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) >> * entry. Always do both to keep code simple. */ >> vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; >> /* Make sure used event never go backwards */ >> - if (!vring_need_event(vring_used_event(&vq->vring), >> - vq->vring.avail->idx, last_used_idx)) >> + if (vq->vring.avail->idx != vring_used_event(&vq->vring) && >> + !vring_need_event(vring_used_event(&vq->vring), >> + vq->vring.avail...

...>> @@ -567,14 +567,32 @@ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) >> * entry. Always do both to keep code simple. */ >> vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; >> /* Make sure used event never go backwards */ >> - if (!vring_need_event(vring_used_event(&vq->vring), >> - vq->vring.avail->idx, last_used_idx)) >> + if (vq->vring.avail->idx != vring_used_event(&vq->vring) && >> + !vring_need_event(vring_used_event(&vq->vring), >> + vq->vring.avail...

On 2018?05?03? 10:09, Tiwei Bie wrote: >>>> So how about we use the straightforward way then? >>> You mean we do new += vq->vring_packed.num instead >>> of event_idx -= vq->vring_packed.num before calling >>> vring_need_event()? >>> >>> The problem is that, the second param (new_idx) of >>> vring_need_event() will be used for: >>> >>> (__u16)(new_idx - event_idx - 1) >>> (__u16)(new_idx - old) >>> >>> So if we change new, we will need to change old...

On 2018?05?03? 10:09, Tiwei Bie wrote: >>>> So how about we use the straightforward way then? >>> You mean we do new += vq->vring_packed.num instead >>> of event_idx -= vq->vring_packed.num before calling >>> vring_need_event()? >>> >>> The problem is that, the second param (new_idx) of >>> vring_need_event() will be used for: >>> >>> (__u16)(new_idx - event_idx - 1) >>> (__u16)(new_idx - old) >>> >>> So if we change new, we will need to change old...

...index bbc3043..5fd3fbc 100644 --- a/tools/virtio/ringtest/virtio_ring_0_9.c +++ b/tools/virtio/ringtest/virtio_ring_0_9.c @@ -225,16 +225,18 @@ bool enable_call() void kick_available(void) { + bool need; + /* Flush in previous flags write */ /* Barrier C (for pairing) */ smp_mb(); - if (!vring_need_event(vring_avail_event(&ring), - guest.avail_idx, - guest.kicked_avail_idx)) - return; + need = vring_need_event(vring_avail_event(&ring), + guest.avail_idx, + guest.kicked_avail_idx); guest.kicked_avail_idx = guest.avail_idx; - kick(); + if (need) + kick(); } /*...