On 10/23/2015 12:57 AM, Stephen Hemminger wrote:
> On Thu, 22 Oct 2015 20:09:50 +0800
> Huawei Xie <huawei.xie at intel.com> wrote:
>
>> Changes in v4:
>> - move virtio_xmit_cleanup ahead to free descriptors earlier
>>
>> Changes in v3:
>> - Remove return at the end of void function
>> - Remove always_inline attribute for virtio_xmit_cleanup
>> bulk free of mbufs when clean used ring.
>> shift operation of idx could be saved if vq_free_cnt means
>> free slots rather than free descriptors.
>>
>> TODO: rearrange vq data structure, pack the stats var together so that we
>> could use one vec instruction to update all of them.
>>
>> Signed-off-by: Huawei Xie <huawei.xie at intel.com>
>> ---
>>  drivers/net/virtio/virtio_ethdev.h      |  3 ++
>>  drivers/net/virtio/virtio_rxtx_simple.c | 93 
>> +++++++++++++++++++++++++++++++++
>>  2 files changed, 96 insertions(+)
>>
>> diff --git a/drivers/net/virtio/virtio_ethdev.h 
>> b/drivers/net/virtio/virtio_ethdev.h
>> index d7797ab..ae2d47d 100644
>> --- a/drivers/net/virtio/virtio_ethdev.h
>> +++ b/drivers/net/virtio/virtio_ethdev.h
>> @@ -111,6 +111,9 @@ uint16_t virtio_xmit_pkts(void *tx_queue, struct 
>> rte_mbuf **tx_pkts,
>>  uint16_t virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
>>              uint16_t nb_pkts);
>>  
>> +uint16_t virtio_xmit_pkts_simple(void *tx_queue, struct rte_mbuf **tx_pkts,
>> +            uint16_t nb_pkts);
>> +
>>  /*
>>   * The VIRTIO_NET_F_GUEST_TSO[46] features permit the host to send us
>>   * frames larger than 1514 bytes. We do not yet support software LRO
>> diff --git a/drivers/net/virtio/virtio_rxtx_simple.c 
>> b/drivers/net/virtio/virtio_rxtx_simple.c
>> index ef17562..79b4f7f 100644
>> --- a/drivers/net/virtio/virtio_rxtx_simple.c
>> +++ b/drivers/net/virtio/virtio_rxtx_simple.c
>> @@ -288,6 +288,99 @@ virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf 
>> **rx_pkts,
>>      return nb_pkts_received;
>>  }
>>  
>> +#define VIRTIO_TX_FREE_THRESH 32
>> +#define VIRTIO_TX_MAX_FREE_BUF_SZ 32
>> +#define VIRTIO_TX_FREE_NR 32
>> +/* TODO: vq->tx_free_cnt could mean num of free slots so we could avoid 
>> shift */
>> +static inline void
>> +virtio_xmit_cleanup(struct virtqueue *vq)
>> +{
>> +    uint16_t i, desc_idx;
>> +    int nb_free = 0;
>> +    struct rte_mbuf *m, *free[VIRTIO_TX_MAX_FREE_BUF_SZ];
>> +
>> +    desc_idx = (uint16_t)(vq->vq_used_cons_idx &
>> +            ((vq->vq_nentries >> 1) - 1));
>> +    free[0] = (struct rte_mbuf *)vq->vq_descx[desc_idx++].cookie;
>> +    nb_free = 1;
>> +
>> +    for (i = 1; i < VIRTIO_TX_FREE_NR; i++) {
>> +            m = (struct rte_mbuf *)vq->vq_descx[desc_idx++].cookie;
>> +            if (likely(m->pool == free[0]->pool))
>> +                    free[nb_free++] = m;
>> +            else {
>> +                    rte_mempool_put_bulk(free[0]->pool, (void **)free,
>> +                            nb_free);
>> +                    free[0] = m;
>> +                    nb_free = 1;
>> +            }
>> +    }
>> +
>> +    rte_mempool_put_bulk(free[0]->pool, (void **)free, nb_free);
>> +    vq->vq_used_cons_idx += VIRTIO_TX_FREE_NR;
>> +    vq->vq_free_cnt += (VIRTIO_TX_FREE_NR << 1);
>> +}
> I think you need to handle refcount, here is a similar patch
> for ixgbe.
ok, like this:

m = (struct rte_mbuf *)vq->vq_descx[desc_idx++].cookie;
if (likely(m != NULL)) {
    ...

>
> Subject: ixgbe: speed up transmit
>
> Coalesce transmit buffers and put them back into the pool
> in one burst.
>
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
>
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> @@ -120,12 +120,16 @@ rte_rxmbuf_alloc(struct rte_mempool *mp)
>   * Check for descriptors with their DD bit set and free mbufs.
>   * Return the total number of buffers freed.
>   */
> +#define TX_FREE_BULK 32
> +
>  static inline int __attribute__((always_inline))
>  ixgbe_tx_free_bufs(struct ixgbe_tx_queue *txq)
>  {
>       struct ixgbe_tx_entry *txep;
>       uint32_t status;
> -     int i;
> +     int i, n = 0;
> +     struct rte_mempool *txpool = NULL;
> +     struct rte_mbuf *free_list[TX_FREE_BULK];
>  
>       /* check DD bit on threshold descriptor */
>       status = txq->tx_ring[txq->tx_next_dd].wb.status;
> @@ -138,20 +142,26 @@ ixgbe_tx_free_bufs(struct ixgbe_tx_queue
>        */
>       txep = &(txq->sw_ring[txq->tx_next_dd - (txq->tx_rs_thresh - 1)]);
>  
> -     /* free buffers one at a time */
> -     if ((txq->txq_flags & (uint32_t)ETH_TXQ_FLAGS_NOREFCOUNT) != 0) {
> -             for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
> -                     txep->mbuf->next = NULL;
> -                     rte_mempool_put(txep->mbuf->pool, txep->mbuf);
> -                     txep->mbuf = NULL;
> -             }
> -     } else {
> -             for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
> -                     rte_pktmbuf_free_seg(txep->mbuf);
> -                     txep->mbuf = NULL;
> +     for (i = 0; i < txq->tx_rs_thresh; ++i, ++txep) {
> +             struct rte_mbuf *m;
> +
> +             /* free buffers one at a time */
> +             m = __rte_pktmbuf_prefree_seg(txep->mbuf);
> +             txep->mbuf = NULL;
> +
> +             if (n >= TX_FREE_BULK  ||
check whether m is NULL here.
> +                 (n > 0 && m->pool != txpool)) {
> +                     rte_mempool_put_bulk(txpool, (void **)free_list, n);
> +                     n = 0;
>               }
> +
> +             txpool = m->pool;
> +             free_list[n++] = m;
>       }
>  
> +     if (n > 0)
> +             rte_mempool_put_bulk(txpool, (void **)free_list, n);
> +
>       /* buffers were freed, update counters */
>       txq->nb_tx_free = (uint16_t)(txq->nb_tx_free + txq->tx_rs_thresh);
>       txq->tx_next_dd = (uint16_t)(txq->tx_next_dd + txq->tx_rs_thresh);
>
>

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