[ovs-dev,v8,11/13] netdev-dpdk: copy large packet to multi-seg. mbufs

Message ID 1528734090-220990-13-git-send-email-tiago.lam@intel.com
State Superseded
Headers show
Series
  • Support multi-segment mbufs
Related show

Commit Message

Lam, Tiago June 11, 2018, 4:21 p.m.
From: Mark Kavanagh <mark.b.kavanagh@intel.com>

Currently, packets are only copied to a single segment in the function
dpdk_do_tx_copy(). This could be an issue in the case of jumbo frames,
particularly when multi-segment mbufs are involved.

This patch calculates the number of segments needed by a packet and
copies the data to each segment.

A new function, dpdk_buf_alloc(), has also been introduced as a wrapper
around the nonpmd_mp_mutex to serialise allocations from a non-pmd
context.

Co-authored-by: Michael Qiu <qiudayu@chinac.com>
Co-authored-by: Tiago Lam <tiago.lam@intel.com>

Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com>
Signed-off-by: Michael Qiu <qiudayu@chinac.com>
Signed-off-by: Tiago Lam <tiago.lam@intel.com>
---
 lib/netdev-dpdk.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 84 insertions(+), 10 deletions(-)

Comments

Eelco Chaudron June 18, 2018, 1:15 p.m. | #1
On 11 Jun 2018, at 18:21, Tiago Lam wrote:

> From: Mark Kavanagh <mark.b.kavanagh@intel.com>
>
> Currently, packets are only copied to a single segment in the function
> dpdk_do_tx_copy(). This could be an issue in the case of jumbo frames,
> particularly when multi-segment mbufs are involved.
>
> This patch calculates the number of segments needed by a packet and
> copies the data to each segment.
>
> A new function, dpdk_buf_alloc(), has also been introduced as a 
> wrapper
> around the nonpmd_mp_mutex to serialise allocations from a non-pmd
> context.
>
> Co-authored-by: Michael Qiu <qiudayu@chinac.com>
> Co-authored-by: Tiago Lam <tiago.lam@intel.com>
>
> Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com>
> Signed-off-by: Michael Qiu <qiudayu@chinac.com>
> Signed-off-by: Tiago Lam <tiago.lam@intel.com>
> ---
>  lib/netdev-dpdk.c | 94 
> +++++++++++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 84 insertions(+), 10 deletions(-)
>
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index 9b1fb9a..0079e28 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -515,6 +515,22 @@ dpdk_rte_mzalloc(size_t sz)
>      return rte_zmalloc(OVS_VPORT_DPDK, sz, OVS_CACHE_LINE_SIZE);
>  }
>
> +static struct rte_mbuf *
> +dpdk_buf_alloc(struct rte_mempool *mp)
> +{
> +    if (!dpdk_thread_is_pmd()) {
> +        ovs_mutex_lock(&nonpmd_mp_mutex);
Can you explain why the lock is needed here for non PMD threads?
> +    }
> +
> +    struct rte_mbuf *mbuf = rte_pktmbuf_alloc(mp);
> +
> +    if (!dpdk_thread_is_pmd()) {
> +        ovs_mutex_unlock(&nonpmd_mp_mutex);
> +    }
> +
> +    return mbuf;
> +}
> +
>  void
>  free_dpdk_buf(struct dp_packet *p)
>  {
> @@ -2167,6 +2183,71 @@ out:
>      }
>  }
>
> +static int

a bool, true for success might be more usefull here.

> +dpdk_prep_tx_buf(struct dp_packet *packet, struct rte_mbuf **head,
> +                 struct rte_mempool *mp)

Maybe the function name should be more what it's doing, i.e 
dpdk_clone_dp_packet_to_mbuf().

> +{
> +    struct rte_mbuf *temp;
> +    uint32_t size = dp_packet_size(packet);
> +    uint16_t max_data_len, data_len;
> +    uint32_t nb_segs = 0;
> +    int i;
> +
> +    temp = *head = dpdk_buf_alloc(mp);
> +    if (OVS_UNLIKELY(!temp)) {
> +        return 1;
> +    }
> +
> +    /* All new allocated mbuf's max data len is the same */
> +    max_data_len = temp->buf_len - temp->data_off;
> +
> +    /* Calculate # of output mbufs. */
> +    nb_segs = size / max_data_len;
> +    if (size % max_data_len) {
> +        nb_segs = nb_segs + 1;
> +    }
> +
> +    /* Allocate additional mbufs when multiple output mbufs required. 
> */
> +    for (i = 1; i < nb_segs; i++) {
> +        temp->next = dpdk_buf_alloc(mp);
> +        if (!temp->next) {
> +            free_dpdk_buf((struct dp_packet *) *head);
> +            *head = NULL;
> +            break;
> +        }
> +        temp = temp->next;
> +    }
> +    /* We have to do a copy for now */
> +    rte_pktmbuf_pkt_len(*head) = size;
> +    temp = *head;
> +
> +    data_len = size < max_data_len ? size: max_data_len;

Can we use max_data_len to copy? It's only valid if rte_pktmbuf_mtod() 
returns the first byte, but after alloc it's 
rte_pktmbuf_reset_headroom(). So we will overwrite invalid memory.

> +    if (packet->source == DPBUF_DPDK) {
> +        *head = &(packet->mbuf);
> +        while (temp && head && size > 0) {
> +            rte_memcpy(rte_pktmbuf_mtod(temp, void *),
> +                    dp_packet_data((struct dp_packet *)head), 
> data_len);

Here you assume source and destination mbuf sizes are the same...
Also use container_of for "(struct dp_packet *)head)"

> +            rte_pktmbuf_data_len(temp) = data_len;
> +            *head = (*head)->next;
> +            size = size - data_len;
> +            data_len =  size < max_data_len ? size: max_data_len;
> +            temp = temp->next;
> +        }
> +    } else {

Why not use dp_packet_mbuf_write() here?

> +        int offset = 0;
> +        while (temp && size > 0) {
> +            memcpy(rte_pktmbuf_mtod(temp, void *),
> +                    dp_packet_at(packet, offset, data_len), 
> data_len);
> +            rte_pktmbuf_data_len(temp) = data_len;
> +            temp = temp->next;
> +            size = size - data_len;
> +            offset += data_len;
> +            data_len = size < max_data_len ? size: max_data_len;
> +        }
> +    }
> +    return 0;
> +}
> +
>  /* Tx function. Transmit packets indefinitely */
>  static void
>  dpdk_do_tx_copy(struct netdev *netdev, int qid, struct 
> dp_packet_batch *batch)
> @@ -2183,6 +2264,7 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, 
> struct dp_packet_batch *batch)
>      struct rte_mbuf *pkts[PKT_ARRAY_SIZE];
>      uint32_t cnt = batch_cnt;
>      uint32_t dropped = 0;
> +    uint32_t i;
>
>      if (dev->type != DPDK_DEV_VHOST) {
>          /* Check if QoS has been configured for this netdev. */
> @@ -2193,27 +2275,19 @@ dpdk_do_tx_copy(struct netdev *netdev, int 
> qid, struct dp_packet_batch *batch)
>
>      uint32_t txcnt = 0;
>
> -    for (uint32_t i = 0; i < cnt; i++) {
> +    for (i = 0; i < cnt; i++) {
>          struct dp_packet *packet = batch->packets[i];
>          uint32_t size = dp_packet_size(packet);
> -
>          if (OVS_UNLIKELY(size > dev->max_packet_len)) {
>              VLOG_WARN_RL(&rl, "Too big size %u max_packet_len %d",
>                           size, dev->max_packet_len);
> -
>              dropped++;
>              continue;
>          }
> -
> -        pkts[txcnt] = rte_pktmbuf_alloc(dev->mp);
> -        if (OVS_UNLIKELY(!pkts[txcnt])) {
> +        if (dpdk_prep_tx_buf(packet, &pkts[txcnt], dev->mp)) {
>              dropped += cnt - i;
>              break;
>          }
> -
> -        /* We have to do a copy for now */
> -        memcpy(rte_pktmbuf_mtod(pkts[txcnt], void *),
> -               dp_packet_data(packet), size);
>          dp_packet_set_size((struct dp_packet *)pkts[txcnt], size);
>          dp_packet_copy_mbuf_flags((struct dp_packet *)pkts[txcnt], 
> packet);
>
> -- 
> 2.7.4
Lam, Tiago June 22, 2018, 7:05 p.m. | #2
On 18/06/2018 14:15, Eelco Chaudron wrote:
> 
> 
> On 11 Jun 2018, at 18:21, Tiago Lam wrote:
> 
>> From: Mark Kavanagh <mark.b.kavanagh@intel.com>
>>
>> Currently, packets are only copied to a single segment in the function
>> dpdk_do_tx_copy(). This could be an issue in the case of jumbo frames,
>> particularly when multi-segment mbufs are involved.
>>
>> This patch calculates the number of segments needed by a packet and
>> copies the data to each segment.
>>
>> A new function, dpdk_buf_alloc(), has also been introduced as a 
>> wrapper
>> around the nonpmd_mp_mutex to serialise allocations from a non-pmd
>> context.
>>
>> Co-authored-by: Michael Qiu <qiudayu@chinac.com>
>> Co-authored-by: Tiago Lam <tiago.lam@intel.com>
>>
>> Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com>
>> Signed-off-by: Michael Qiu <qiudayu@chinac.com>
>> Signed-off-by: Tiago Lam <tiago.lam@intel.com>
>> ---
>>  lib/netdev-dpdk.c | 94 
>> +++++++++++++++++++++++++++++++++++++++++++++++++------
>>  1 file changed, 84 insertions(+), 10 deletions(-)
>>
>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>> index 9b1fb9a..0079e28 100644
>> --- a/lib/netdev-dpdk.c
>> +++ b/lib/netdev-dpdk.c
>> @@ -515,6 +515,22 @@ dpdk_rte_mzalloc(size_t sz)
>>      return rte_zmalloc(OVS_VPORT_DPDK, sz, OVS_CACHE_LINE_SIZE);
>>  }
>>
>> +static struct rte_mbuf *
>> +dpdk_buf_alloc(struct rte_mempool *mp)
>> +{
>> +    if (!dpdk_thread_is_pmd()) {
>> +        ovs_mutex_lock(&nonpmd_mp_mutex);
> Can you explain why the lock is needed here for non PMD threads?
>> +    }
>> +
>> +    struct rte_mbuf *mbuf = rte_pktmbuf_alloc(mp);
>> +
>> +    if (!dpdk_thread_is_pmd()) {
>> +        ovs_mutex_unlock(&nonpmd_mp_mutex);
>> +    }
>> +
>> +    return mbuf;
>> +}
>> +
>>  void
>>  free_dpdk_buf(struct dp_packet *p)
>>  {
>> @@ -2167,6 +2183,71 @@ out:
>>      }
>>  }
>>
>> +static int
> 
> a bool, true for success might be more usefull here.

I've updated this part to return better error codes. More specifically,
`ENOMEM` so the caller knows there's no memory.

> 
>> +dpdk_prep_tx_buf(struct dp_packet *packet, struct rte_mbuf **head,
>> +                 struct rte_mempool *mp)
> 
> Maybe the function name should be more what it's doing, i.e 
> dpdk_clone_dp_packet_to_mbuf().
> 

Sounds clearer to me, aside from the clone since it's different types of
packets. What about `dpdk_copy_dp_packet_to_mbuf()`?

>> +{
>> +    struct rte_mbuf *temp;
>> +    uint32_t size = dp_packet_size(packet);
>> +    uint16_t max_data_len, data_len;
>> +    uint32_t nb_segs = 0;
>> +    int i;
>> +
>> +    temp = *head = dpdk_buf_alloc(mp);
>> +    if (OVS_UNLIKELY(!temp)) {
>> +        return 1;
>> +    }
>> +
>> +    /* All new allocated mbuf's max data len is the same */
>> +    max_data_len = temp->buf_len - temp->data_off;
>> +
>> +    /* Calculate # of output mbufs. */
>> +    nb_segs = size / max_data_len;
>> +    if (size % max_data_len) {
>> +        nb_segs = nb_segs + 1;
>> +    }
>> +
>> +    /* Allocate additional mbufs when multiple output mbufs required. 
>> */
>> +    for (i = 1; i < nb_segs; i++) {
>> +        temp->next = dpdk_buf_alloc(mp);
>> +        if (!temp->next) {
>> +            free_dpdk_buf((struct dp_packet *) *head);
>> +            *head = NULL;
>> +            break;
>> +        }
>> +        temp = temp->next;
>> +    }
>> +    /* We have to do a copy for now */
>> +    rte_pktmbuf_pkt_len(*head) = size;
>> +    temp = *head;
>> +
>> +    data_len = size < max_data_len ? size: max_data_len;
> 
> Can we use max_data_len to copy? It's only valid if rte_pktmbuf_mtod() 
> returns the first byte, but after alloc it's 
> rte_pktmbuf_reset_headroom(). So we will overwrite invalid memory.
> 
>> +    if (packet->source == DPBUF_DPDK) {
>> +        *head = &(packet->mbuf);
>> +        while (temp && head && size > 0) {
>> +            rte_memcpy(rte_pktmbuf_mtod(temp, void *),
>> +                    dp_packet_data((struct dp_packet *)head), 
>> data_len);
> 
> Here you assume source and destination mbuf sizes are the same...
> Also use container_of for "(struct dp_packet *)head)"
> 
>> +            rte_pktmbuf_data_len(temp) = data_len;
>> +            *head = (*head)->next;
>> +            size = size - data_len;
>> +            data_len =  size < max_data_len ? size: max_data_len;
>> +            temp = temp->next;
>> +        }
>> +    } else {
> 
> Why not use dp_packet_mbuf_write() here?
> 

I missed this. I'll take this approach as well, thanks.

Tiago.
Eelco Chaudron June 26, 2018, 1:06 p.m. | #3
On 22 Jun 2018, at 21:05, Lam, Tiago wrote:

> On 18/06/2018 14:15, Eelco Chaudron wrote:
>>
>>
>> On 11 Jun 2018, at 18:21, Tiago Lam wrote:
>>
>>> From: Mark Kavanagh <mark.b.kavanagh@intel.com>
>>>
>>> Currently, packets are only copied to a single segment in the function
>>> dpdk_do_tx_copy(). This could be an issue in the case of jumbo frames,
>>> particularly when multi-segment mbufs are involved.
>>>
>>> This patch calculates the number of segments needed by a packet and
>>> copies the data to each segment.
>>>
>>> A new function, dpdk_buf_alloc(), has also been introduced as a
>>> wrapper
>>> around the nonpmd_mp_mutex to serialise allocations from a non-pmd
>>> context.
>>>
>>> Co-authored-by: Michael Qiu <qiudayu@chinac.com>
>>> Co-authored-by: Tiago Lam <tiago.lam@intel.com>
>>>
>>> Signed-off-by: Mark Kavanagh <mark.b.kavanagh@intel.com>
>>> Signed-off-by: Michael Qiu <qiudayu@chinac.com>
>>> Signed-off-by: Tiago Lam <tiago.lam@intel.com>
>>> ---
>>>  lib/netdev-dpdk.c | 94
>>> +++++++++++++++++++++++++++++++++++++++++++++++++------
>>>  1 file changed, 84 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>>> index 9b1fb9a..0079e28 100644
>>> --- a/lib/netdev-dpdk.c
>>> +++ b/lib/netdev-dpdk.c
>>> @@ -515,6 +515,22 @@ dpdk_rte_mzalloc(size_t sz)
>>>      return rte_zmalloc(OVS_VPORT_DPDK, sz, OVS_CACHE_LINE_SIZE);
>>>  }
>>>
>>> +static struct rte_mbuf *
>>> +dpdk_buf_alloc(struct rte_mempool *mp)
>>> +{
>>> +    if (!dpdk_thread_is_pmd()) {
>>> +        ovs_mutex_lock(&nonpmd_mp_mutex);
>> Can you explain why the lock is needed here for non PMD threads?
>>> +    }
>>> +
>>> +    struct rte_mbuf *mbuf = rte_pktmbuf_alloc(mp);
>>> +
>>> +    if (!dpdk_thread_is_pmd()) {
>>> +        ovs_mutex_unlock(&nonpmd_mp_mutex);
>>> +    }
>>> +
>>> +    return mbuf;
>>> +}
>>> +
>>>  void
>>>  free_dpdk_buf(struct dp_packet *p)
>>>  {
>>> @@ -2167,6 +2183,71 @@ out:
>>>      }
>>>  }
>>>
>>> +static int
>>
>> a bool, true for success might be more usefull here.
>
> I've updated this part to return better error codes. More specifically,
> `ENOMEM` so the caller knows there's no memory.
>

Even better…

>>
>>> +dpdk_prep_tx_buf(struct dp_packet *packet, struct rte_mbuf **head,
>>> +                 struct rte_mempool *mp)
>>
>> Maybe the function name should be more what it's doing, i.e
>> dpdk_clone_dp_packet_to_mbuf().
>>
>
> Sounds clearer to me, aside from the clone since it's different types of
> packets. What about `dpdk_copy_dp_packet_to_mbuf()`?
>

Sounds good to me.

>>> +{
>>> +    struct rte_mbuf *temp;
>>> +    uint32_t size = dp_packet_size(packet);
>>> +    uint16_t max_data_len, data_len;
>>> +    uint32_t nb_segs = 0;
>>> +    int i;
>>> +
>>> +    temp = *head = dpdk_buf_alloc(mp);
>>> +    if (OVS_UNLIKELY(!temp)) {
>>> +        return 1;
>>> +    }
>>> +
>>> +    /* All new allocated mbuf's max data len is the same */
>>> +    max_data_len = temp->buf_len - temp->data_off;
>>> +
>>> +    /* Calculate # of output mbufs. */
>>> +    nb_segs = size / max_data_len;
>>> +    if (size % max_data_len) {
>>> +        nb_segs = nb_segs + 1;
>>> +    }
>>> +
>>> +    /* Allocate additional mbufs when multiple output mbufs required.
>>> */
>>> +    for (i = 1; i < nb_segs; i++) {
>>> +        temp->next = dpdk_buf_alloc(mp);
>>> +        if (!temp->next) {
>>> +            free_dpdk_buf((struct dp_packet *) *head);
>>> +            *head = NULL;
>>> +            break;
>>> +        }
>>> +        temp = temp->next;
>>> +    }
>>> +    /* We have to do a copy for now */
>>> +    rte_pktmbuf_pkt_len(*head) = size;
>>> +    temp = *head;
>>> +
>>> +    data_len = size < max_data_len ? size: max_data_len;
>>
>> Can we use max_data_len to copy? It's only valid if rte_pktmbuf_mtod()
>> returns the first byte, but after alloc it's
>> rte_pktmbuf_reset_headroom(). So we will overwrite invalid memory.
>>
>>> +    if (packet->source == DPBUF_DPDK) {
>>> +        *head = &(packet->mbuf);
>>> +        while (temp && head && size > 0) {
>>> +            rte_memcpy(rte_pktmbuf_mtod(temp, void *),
>>> +                    dp_packet_data((struct dp_packet *)head),
>>> data_len);
>>
>> Here you assume source and destination mbuf sizes are the same...
>> Also use container_of for "(struct dp_packet *)head)"
>>
>>> +            rte_pktmbuf_data_len(temp) = data_len;
>>> +            *head = (*head)->next;
>>> +            size = size - data_len;
>>> +            data_len =  size < max_data_len ? size: max_data_len;
>>> +            temp = temp->next;
>>> +        }
>>> +    } else {
>>
>> Why not use dp_packet_mbuf_write() here?
>>
>
> I missed this. I'll take this approach as well, thanks.

I assume you also mean the other two inlines above this one.

Patch

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index 9b1fb9a..0079e28 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -515,6 +515,22 @@  dpdk_rte_mzalloc(size_t sz)
     return rte_zmalloc(OVS_VPORT_DPDK, sz, OVS_CACHE_LINE_SIZE);
 }
 
+static struct rte_mbuf *
+dpdk_buf_alloc(struct rte_mempool *mp)
+{
+    if (!dpdk_thread_is_pmd()) {
+        ovs_mutex_lock(&nonpmd_mp_mutex);
+    }
+
+    struct rte_mbuf *mbuf = rte_pktmbuf_alloc(mp);
+
+    if (!dpdk_thread_is_pmd()) {
+        ovs_mutex_unlock(&nonpmd_mp_mutex);
+    }
+
+    return mbuf;
+}
+
 void
 free_dpdk_buf(struct dp_packet *p)
 {
@@ -2167,6 +2183,71 @@  out:
     }
 }
 
+static int
+dpdk_prep_tx_buf(struct dp_packet *packet, struct rte_mbuf **head,
+                 struct rte_mempool *mp)
+{
+    struct rte_mbuf *temp;
+    uint32_t size = dp_packet_size(packet);
+    uint16_t max_data_len, data_len;
+    uint32_t nb_segs = 0;
+    int i;
+
+    temp = *head = dpdk_buf_alloc(mp);
+    if (OVS_UNLIKELY(!temp)) {
+        return 1;
+    }
+
+    /* All new allocated mbuf's max data len is the same */
+    max_data_len = temp->buf_len - temp->data_off;
+
+    /* Calculate # of output mbufs. */
+    nb_segs = size / max_data_len;
+    if (size % max_data_len) {
+        nb_segs = nb_segs + 1;
+    }
+
+    /* Allocate additional mbufs when multiple output mbufs required. */
+    for (i = 1; i < nb_segs; i++) {
+        temp->next = dpdk_buf_alloc(mp);
+        if (!temp->next) {
+            free_dpdk_buf((struct dp_packet *) *head);
+            *head = NULL;
+            break;
+        }
+        temp = temp->next;
+    }
+    /* We have to do a copy for now */
+    rte_pktmbuf_pkt_len(*head) = size;
+    temp = *head;
+
+    data_len = size < max_data_len ? size: max_data_len;
+    if (packet->source == DPBUF_DPDK) {
+        *head = &(packet->mbuf);
+        while (temp && head && size > 0) {
+            rte_memcpy(rte_pktmbuf_mtod(temp, void *),
+                    dp_packet_data((struct dp_packet *)head), data_len);
+            rte_pktmbuf_data_len(temp) = data_len;
+            *head = (*head)->next;
+            size = size - data_len;
+            data_len =  size < max_data_len ? size: max_data_len;
+            temp = temp->next;
+        }
+    } else {
+        int offset = 0;
+        while (temp && size > 0) {
+            memcpy(rte_pktmbuf_mtod(temp, void *),
+                    dp_packet_at(packet, offset, data_len), data_len);
+            rte_pktmbuf_data_len(temp) = data_len;
+            temp = temp->next;
+            size = size - data_len;
+            offset += data_len;
+            data_len = size < max_data_len ? size: max_data_len;
+        }
+    }
+    return 0;
+}
+
 /* Tx function. Transmit packets indefinitely */
 static void
 dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch)
@@ -2183,6 +2264,7 @@  dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch)
     struct rte_mbuf *pkts[PKT_ARRAY_SIZE];
     uint32_t cnt = batch_cnt;
     uint32_t dropped = 0;
+    uint32_t i;
 
     if (dev->type != DPDK_DEV_VHOST) {
         /* Check if QoS has been configured for this netdev. */
@@ -2193,27 +2275,19 @@  dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch)
 
     uint32_t txcnt = 0;
 
-    for (uint32_t i = 0; i < cnt; i++) {
+    for (i = 0; i < cnt; i++) {
         struct dp_packet *packet = batch->packets[i];
         uint32_t size = dp_packet_size(packet);
-
         if (OVS_UNLIKELY(size > dev->max_packet_len)) {
             VLOG_WARN_RL(&rl, "Too big size %u max_packet_len %d",
                          size, dev->max_packet_len);
-
             dropped++;
             continue;
         }
-
-        pkts[txcnt] = rte_pktmbuf_alloc(dev->mp);
-        if (OVS_UNLIKELY(!pkts[txcnt])) {
+        if (dpdk_prep_tx_buf(packet, &pkts[txcnt], dev->mp)) {
             dropped += cnt - i;
             break;
         }
-
-        /* We have to do a copy for now */
-        memcpy(rte_pktmbuf_mtod(pkts[txcnt], void *),
-               dp_packet_data(packet), size);
         dp_packet_set_size((struct dp_packet *)pkts[txcnt], size);
         dp_packet_copy_mbuf_flags((struct dp_packet *)pkts[txcnt], packet);