Thanks for reviewing
On Fri, May 2, 2014 at 10:00 PM, John Fastabend
<john.r.fastab...@intel.com> wrote:
> On 5/2/2014 6:19 AM, Jesper Dangaard Brouer wrote:
>>
>> On Fri, 2 May 2014 15:18:12 +0800
>> Zhouyi Zhou <zhouzho...@gmail.com> wrote:
>>
>>> As http://www.spinics.net/lists/netdev/msg165015.html
>>> pktgen generates shared packet through vlan interface will cause
>>> oops because of duplicate entering tc queue.
>>>
>>> Try to solve this problem by means of packet clone instead of sharing.
>>
>>
>> I really don't like adding this stuff to the fast path of pktgen.
>>
>> Why would you use pktgen on a VLAN?
I use pktgen on a VLAN under a special circumstance.
>
>
> Its a good way to test qdiscs. When you run pktgen over the VLAN
> you exercise the lower devices qdisc.
>
> Although I never submitted a patch like this because I figured it
> was a corner case and we would want to keep the hotpath clean.
>
I think is_vlan_dev(odev) have great chances to be in a cache line
that seldom got reset. Could we only judge is_vlan_dev(odev) in my
first if statement?
Also I guess if (nskb && !IS_ERR(nskb)) happens in rarely reached
cases when the interface is not overload.
>
>>
>> Why don't you use the "vlan_id" feature available in pktgen, and send
>> in the lower real device?
Could we automatically convert the VLAN device's joining effort to
real device + vlan_id settings in pkt_dev.
or could we issue a warning or a suggestion
when user try to add a VLAN device to the pktgen thread?
>>
>>
>>
>>> Signed-off-by: Zhouyi Zhou <yizhouz...@ict.ac.cn>
>>> ---
>>> net/core/pktgen.c | 20 +++++++++++++++++---
>>> 1 files changed, 17 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
>>> index 0304f98..ced07fc 100644
>>> --- a/net/core/pktgen.c
>>> +++ b/net/core/pktgen.c
>>> @@ -3297,6 +3297,7 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
>>> netdev_tx_t (*xmit)(struct sk_buff *, struct net_device *)
>>> = odev->netdev_ops->ndo_start_xmit;
>>> struct netdev_queue *txq;
>>> + struct sk_buff *nskb = NULL;
>>> u16 queue_map;
>>> int ret;
>>>
>>> @@ -3347,8 +3348,18 @@ static void pktgen_xmit(struct pktgen_dev
>>> *pkt_dev)
>>> pkt_dev->last_ok = 0;
>>> goto unlock;
>>> }
>>> - atomic_inc(&(pkt_dev->skb->users));
>>> - ret = (*xmit)(pkt_dev->skb, odev);
>>> +
>>> + if (pkt_dev->clone_skb && is_vlan_dev(odev)) {
>>> + nskb = skb_clone(pkt_dev->skb, GFP_ATOMIC);
>>> + ret = -ENOMEM;
>>> + if (nskb)
>>> + ret = (*xmit)(nskb, odev);
>>> + else
>>> + nskb = ERR_PTR(ret);
>>> + } else {
>>> + atomic_inc(&(pkt_dev->skb->users));
>>> + ret = (*xmit)(pkt_dev->skb, odev);
>>> + }
>>>
>>> switch (ret) {
>>> case NETDEV_TX_OK:
>>> @@ -3372,7 +3383,10 @@ static void pktgen_xmit(struct pktgen_dev
>>> *pkt_dev)
>>> case NETDEV_TX_LOCKED:
>>> case NETDEV_TX_BUSY:
>>> /* Retry it next time */
>>> - atomic_dec(&(pkt_dev->skb->users));
>>> + if (nskb && !IS_ERR(nskb))
>>> + kfree_skb(nskb);
>>> + else
>>> + atomic_dec(&(pkt_dev->skb->users));
>>> pkt_dev->last_ok = 0;
>>> }
>>> unlock:
>>
>>
>>
>>
>
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