[dpdk-dev] [PATCH v4] virtio: Fix vring entry number issue

2014-10-15 Thread Ouyang, Changchun 
Hi Huawei,
I have v5 patch for this comment.
Thanks,
Changchun

> -Original Message-
> From: Xie, Huawei
> Sent: Wednesday, October 15, 2014 12:26 AM
> To: Ouyang, Changchun; dev at dpdk.org
> Subject: RE: [dpdk-dev] [PATCH v4] virtio: Fix vring entry number issue
> 
> 
> 
> > -Original Message-
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ouyang
> Changchun
> > Sent: Tuesday, October 14, 2014 9:04 AM
> > To: dev at dpdk.org
> > Subject: [dpdk-dev] [PATCH v4] virtio: Fix vring entry number issue
> >
> >   Fix one issue in virtio TX: it needs one more vring descriptor to hold the
> virtio
> >   header when transmitting packets, it is used later to determine whether
> to free
> >   more entries from used vring.
> >   It fixes failing to transmit any packet with 1 segment in the
> > circumstance of only
> >   1 descriptor in the vring free list.
> >
> > Signed-off-by: Changchun Ouyang 
> > Reviewed-by: Olivier Matz 
> > ---
> > -V4 change:
> >   Relocate those changelog and annotation here.
> >
> > -V3 change:
> >   Resolve compilation issue due to mbuf re-structure.
> >
> > -V2 change:
> >   Refine description, 'vring descriptor' is more accurate than 'vring 
> > entry';
> >   Accordingly update test condition (it needs one more descriptor for
> > virtio
> > header) to
> >   put packets to transmit queue.
> >
> > -V1 change:
> >   Fix the vring descriptor issue in virtio TX, it needs one more vring
> > descriptor to hold the
> >   virtio header.
> >
> >  lib/librte_pmd_virtio/virtio_rxtx.c | 10 --
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c
> > b/lib/librte_pmd_virtio/virtio_rxtx.c
> > index 0b10108..ac44c65 100644
> > --- a/lib/librte_pmd_virtio/virtio_rxtx.c
> > +++ b/lib/librte_pmd_virtio/virtio_rxtx.c
> > @@ -699,7 +699,8 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf
> > **tx_pkts, uint16_t nb_pkts)
> > num = (uint16_t)(likely(nb_used < VIRTIO_MBUF_BURST_SZ) ?
> nb_used :
> > VIRTIO_MBUF_BURST_SZ);
> >
> > while (nb_tx < nb_pkts) {
> > -   int need = tx_pkts[nb_tx]->pkt.nb_segs - txvq->vq_free_cnt;
> > +   /* Need one more descriptor for virtio header. */
> > +   int need = tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1;
> > int deq_cnt = RTE_MIN(need, (int)num);
> >
> > num -= (deq_cnt > 0) ? deq_cnt : 0; @@ -708,7 +709,12 @@
> > virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t
> > nb_pkts)
> > deq_cnt--;
> > }
> >
> > -   if (tx_pkts[nb_tx]->pkt.nb_segs <= txvq->vq_free_cnt) {
> > +   need = (int)tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt +
> 1;
> > +   /*
> > +* Zero or negative value indicates it has enough free
> > +* decriptors to transmit.
> > +*/
> > +   if (need <= 0) {
> Could we put a branch hint to favor the fast path?
> > txm = tx_pkts[nb_tx];
> > /* Enqueue Packet buffers */
> > error = virtqueue_enqueue_xmit(txvq, txm);
> > --
> > 1.8.4.2

[dpdk-dev] [PATCH v4] virtio: Fix vring entry number issue

2014-10-15 Thread Ouyang Changchun 
  Fix one issue in virtio TX: it needs one more vring descriptor to hold the 
virtio
  header when transmitting packets, it is used later to determine whether to 
free
  more entries from used vring.
  It fixes failing to transmit any packet with 1 segment in the circumstance of 
only
  1 descriptor in the vring free list.

Signed-off-by: Changchun Ouyang 
Reviewed-by: Olivier Matz 
---
-V4 change:
  Relocate those changelog and annotation here.

-V3 change:
  Resolve compilation issue due to mbuf re-structure.

-V2 change:
  Refine description, 'vring descriptor' is more accurate than 'vring entry';
  Accordingly update test condition (it needs one more descriptor for virtio 
header) to
  put packets to transmit queue.

-V1 change:
  Fix the vring descriptor issue in virtio TX, it needs one more vring 
descriptor to hold the
  virtio header.

 lib/librte_pmd_virtio/virtio_rxtx.c | 10 --
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c 
b/lib/librte_pmd_virtio/virtio_rxtx.c
index 0b10108..ac44c65 100644
--- a/lib/librte_pmd_virtio/virtio_rxtx.c
+++ b/lib/librte_pmd_virtio/virtio_rxtx.c
@@ -699,7 +699,8 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, 
uint16_t nb_pkts)
num = (uint16_t)(likely(nb_used < VIRTIO_MBUF_BURST_SZ) ? nb_used : 
VIRTIO_MBUF_BURST_SZ);

while (nb_tx < nb_pkts) {
-   int need = tx_pkts[nb_tx]->pkt.nb_segs - txvq->vq_free_cnt;
+   /* Need one more descriptor for virtio header. */
+   int need = tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1;
int deq_cnt = RTE_MIN(need, (int)num);

num -= (deq_cnt > 0) ? deq_cnt : 0;
@@ -708,7 +709,12 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf 
**tx_pkts, uint16_t nb_pkts)
deq_cnt--;
}

-   if (tx_pkts[nb_tx]->pkt.nb_segs <= txvq->vq_free_cnt) {
+   need = (int)tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1;
+   /*
+* Zero or negative value indicates it has enough free
+* decriptors to transmit.
+*/
+   if (need <= 0) {
txm = tx_pkts[nb_tx];
/* Enqueue Packet buffers */
error = virtqueue_enqueue_xmit(txvq, txm);
-- 
1.8.4.2

[dpdk-dev] [PATCH v4] virtio: Fix vring entry number issue

2014-10-14 Thread Xie, Huawei 


> -Original Message-
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ouyang Changchun
> Sent: Tuesday, October 14, 2014 9:04 AM
> To: dev at dpdk.org
> Subject: [dpdk-dev] [PATCH v4] virtio: Fix vring entry number issue
> 
>   Fix one issue in virtio TX: it needs one more vring descriptor to hold the 
> virtio
>   header when transmitting packets, it is used later to determine whether to 
> free
>   more entries from used vring.
>   It fixes failing to transmit any packet with 1 segment in the circumstance 
> of
> only
>   1 descriptor in the vring free list.
> 
> Signed-off-by: Changchun Ouyang 
> Reviewed-by: Olivier Matz 
> ---
> -V4 change:
>   Relocate those changelog and annotation here.
> 
> -V3 change:
>   Resolve compilation issue due to mbuf re-structure.
> 
> -V2 change:
>   Refine description, 'vring descriptor' is more accurate than 'vring entry';
>   Accordingly update test condition (it needs one more descriptor for virtio
> header) to
>   put packets to transmit queue.
> 
> -V1 change:
>   Fix the vring descriptor issue in virtio TX, it needs one more vring 
> descriptor to
> hold the
>   virtio header.
> 
>  lib/librte_pmd_virtio/virtio_rxtx.c | 10 --
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c
> b/lib/librte_pmd_virtio/virtio_rxtx.c
> index 0b10108..ac44c65 100644
> --- a/lib/librte_pmd_virtio/virtio_rxtx.c
> +++ b/lib/librte_pmd_virtio/virtio_rxtx.c
> @@ -699,7 +699,8 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf
> **tx_pkts, uint16_t nb_pkts)
>   num = (uint16_t)(likely(nb_used < VIRTIO_MBUF_BURST_SZ) ? nb_used :
> VIRTIO_MBUF_BURST_SZ);
> 
>   while (nb_tx < nb_pkts) {
> - int need = tx_pkts[nb_tx]->pkt.nb_segs - txvq->vq_free_cnt;
> + /* Need one more descriptor for virtio header. */
> + int need = tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1;
>   int deq_cnt = RTE_MIN(need, (int)num);
> 
>   num -= (deq_cnt > 0) ? deq_cnt : 0;
> @@ -708,7 +709,12 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf
> **tx_pkts, uint16_t nb_pkts)
>   deq_cnt--;
>   }
> 
> - if (tx_pkts[nb_tx]->pkt.nb_segs <= txvq->vq_free_cnt) {
> + need = (int)tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1;
> + /*
> +  * Zero or negative value indicates it has enough free
> +  * decriptors to transmit.
> +  */
> + if (need <= 0) {
Could we put a branch hint to favor the fast path?
>   txm = tx_pkts[nb_tx];
>   /* Enqueue Packet buffers */
>   error = virtqueue_enqueue_xmit(txvq, txm);
> --
> 1.8.4.2