search for: virtqueue_enable_cb_avail

...>> } >> EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); >> > I see you are also changing virtqueue_enable_cb_prepare, why? This is also used to prevent it from moving the used event backwards. This may happens when we handle tx napi after we publish avail idx as used event (virtqueue_enable_cb_avail() was called). > >> +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) >> +{ >> + struct vring_virtqueue *vq = to_vvq(_vq); >> + bool ret; >> + >> + START_USE(vq); >> + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; >> + vring...

...>> } >> EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); >> > I see you are also changing virtqueue_enable_cb_prepare, why? This is also used to prevent it from moving the used event backwards. This may happens when we handle tx napi after we publish avail idx as used event (virtqueue_enable_cb_avail() was called). > >> +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) >> +{ >> + struct vring_virtqueue *vq = to_vvq(_vq); >> + bool ret; >> + >> + START_USE(vq); >> + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; >> + vring...

...irtqueue_enable_cb_prepare); >>>> >>> I see you are also changing virtqueue_enable_cb_prepare, why? >> This is also used to prevent it from moving the used event backwards. >> This may happens when we handle tx napi after we publish avail idx as >> used event (virtqueue_enable_cb_avail() was called). > So it's wrong exactly in the same way. > > But also, please document this stuff, don't put > unrelated changes in a patch called "introduce > virtqueue_enable_cb_avail". > > >>>> +bool virtqueue_enable_cb_avail(struct virtqueue *_v...

...irtqueue_enable_cb_prepare); >>>> >>> I see you are also changing virtqueue_enable_cb_prepare, why? >> This is also used to prevent it from moving the used event backwards. >> This may happens when we handle tx napi after we publish avail idx as >> used event (virtqueue_enable_cb_avail() was called). > So it's wrong exactly in the same way. > > But also, please document this stuff, don't put > unrelated changes in a patch called "introduce > virtqueue_enable_cb_avail". > > >>>> +bool virtqueue_enable_cb_avail(struct virtqueue *_v...

...q->vring) && + !vring_need_event(vring_used_event(&vq->vring), + vq->vring.avail->idx, last_used_idx)) { vring_used_event(&vq->vring) = last_used_idx; + } END_USE(vq); return last_used_idx; } EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + bool ret; + + START_USE(vq); + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; + vring_used_event(&vq->vring) = vq->vring.avail->idx; + ret = vring_need_event(vq->vring.avail->idx, +...

...q->vring) && + !vring_need_event(vring_used_event(&vq->vring), + vq->vring.avail->idx, last_used_idx)) { vring_used_event(&vq->vring) = last_used_idx; + } END_USE(vq); return last_used_idx; } EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + bool ret; + + START_USE(vq); + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; + vring_used_event(&vq->vring) = vq->vring.avail->idx; + ret = vring_need_event(vq->vring.avail->idx, +...

...SYMBOL_GPL(virtqueue_enable_cb_prepare); > >> > > I see you are also changing virtqueue_enable_cb_prepare, why? > > This is also used to prevent it from moving the used event backwards. > This may happens when we handle tx napi after we publish avail idx as > used event (virtqueue_enable_cb_avail() was called). So it's wrong exactly in the same way. But also, please document this stuff, don't put unrelated changes in a patch called "introduce virtqueue_enable_cb_avail". > > > >> +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) > >> +{ >...

With the help of xmit_more and virtqueue_enable_cb_avail(), this patch enable tx interrupt only for the final skb in the chain if needed. This will help to mitigate tx interrupts. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/net/v...

...vring.avail->idx, last_used_idx)) { > vring_used_event(&vq->vring) = last_used_idx; > + } > END_USE(vq); > return last_used_idx; > } > EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); > I see you are also changing virtqueue_enable_cb_prepare, why? > +bool virtqueue_enable_cb_avail(struct virtqueue *_vq) > +{ > + struct vring_virtqueue *vq = to_vvq(_vq); > + bool ret; > + > + START_USE(vq); > + vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; > + vring_used_event(&vq->vring) = vq->vring.avail->idx; > + ret = vring_need_even...

With the help of xmit_more and virtqueue_enable_cb_avail(), this patch enable tx interrupt only for the final skb in the chain if needed. This will help to mitigate tx interrupts. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/net/v...

According to David, proper accounting and queueing (at all levels, not just TCP sockets) is more important than trying to skim a bunch of cycles by avoiding TX interrupts. Having an event to free the SKB is absolutely essential for the stack to operate correctly. This series tries to enable tx interrupt for virtio-net. The idea is simple: enable tx interrupt and schedule a tx napi to free old

According to David, proper accounting and queueing (at all levels, not just TCP sockets) is more important than trying to skim a bunch of cycles by avoiding TX interrupts. Having an event to free the SKB is absolutely essential for the stack to operate correctly. This series tries to enable tx interrupt for virtio-net. The idea is simple: enable tx interrupt and schedule a tx napi to free old

On Wed, Oct 15, 2014 at 03:25:30PM +0800, Jason Wang wrote: > With the help of xmit_more and virtqueue_enable_cb_avail(), this patch > enable tx interrupt only for the final skb in the chain if > needed. This will help to mitigate tx interrupts. > > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Jason Wang <jasowang at red...

On 10/15/2014 06:22 PM, Michael S. Tsirkin wrote: > On Wed, Oct 15, 2014 at 03:25:30PM +0800, Jason Wang wrote: >> With the help of xmit_more and virtqueue_enable_cb_avail(), this patch >> enable tx interrupt only for the final skb in the chain if >> needed. This will help to mitigate tx interrupts. >> >> Cc: Rusty Russell <rusty at rustcorp.com.au> >> Cc: Michael S. Tsirkin <mst at redhat.com> >> Signed-off-by: Jason W...

On 10/15/2014 06:22 PM, Michael S. Tsirkin wrote: > On Wed, Oct 15, 2014 at 03:25:30PM +0800, Jason Wang wrote: >> With the help of xmit_more and virtqueue_enable_cb_avail(), this patch >> enable tx interrupt only for the final skb in the chain if >> needed. This will help to mitigate tx interrupts. >> >> Cc: Rusty Russell <rusty at rustcorp.com.au> >> Cc: Michael S. Tsirkin <mst at redhat.com> >> Signed-off-by: Jason W...

...callback on the next packet, > which is almost sure to cause an interrupt storm > on the guest. > > > I think it's a bad idea, this is why I used > enable_cb_delayed in my patch. Right, will do this, but may also need to make sure used event never goes back since we may call virtqueue_enable_cb_avail(). > > >> > + napi_schedule_prep(napi)) { >> > + virtqueue_disable_cb(sq->vq); >> > + __napi_schedule(napi); >> > + goto again; >> > + } >> > + } else { >> > + __netif_tx_unlock(txq); >> > + } >> &gt...

...callback on the next packet, > which is almost sure to cause an interrupt storm > on the guest. > > > I think it's a bad idea, this is why I used > enable_cb_delayed in my patch. Right, will do this, but may also need to make sure used event never goes back since we may call virtqueue_enable_cb_avail(). > > >> > + napi_schedule_prep(napi)) { >> > + virtqueue_disable_cb(sq->vq); >> > + __napi_schedule(napi); >> > + goto again; >> > + } >> > + } else { >> > + __netif_tx_unlock(txq); >> > + } >> &gt...

...is almost sure to cause an interrupt storm > > on the guest. > > > > > > I think it's a bad idea, this is why I used > > enable_cb_delayed in my patch. > > Right, will do this, but may also need to make sure used event never > goes back since we may call virtqueue_enable_cb_avail(). That's why my patch always calls virtqueue_enable_cb_delayed. So no need for hacks. Maybe you can review my patch and comment? > > > > > >> > + napi_schedule_prep(napi)) { > >> > + virtqueue_disable_cb(sq->vq); > >> > + __napi...

Orphan skb in ndo_start_xmit() breaks socket accounting and packet queuing. This in fact breaks lots of things such as pktgen and several TCP optimizations. And also make BQL can't be implemented for virtio-net. This patch tries to solve this issue by enabling tx interrupt. To avoid introducing extra spinlocks, a tx napi was scheduled to free those packets. More tx interrupt mitigation

Orphan skb in ndo_start_xmit() breaks socket accounting and packet queuing. This in fact breaks lots of things such as pktgen and several TCP optimizations. And also make BQL can't be implemented for virtio-net. This patch tries to solve this issue by enabling tx interrupt. To avoid introducing extra spinlocks, a tx napi was scheduled to free those packets. More tx interrupt mitigation