Subject: Re: [net-next RFC] pktgen: don't wait for the device who doesn't free skb immediately after sent

From: Jason Wang <[email-masked]>
Date: Tue, 27 Nov 2012 14:45:13 +0800

On 11/27/2012 01:37 AM, Stephen Hemminger wrote:
> On Mon, 26 Nov 2012 15:56:52 +0800
> Jason Wang <[email-masked]> wrote:
>
>> Some deivces do not free the old tx skbs immediately after it has been sent
>> (usually in tx interrupt). One such example is virtio-net which optimizes for
>> virt and only free the possible old tx skbs during the next packet sending. This
>> would lead the pktgen to wait forever in the refcount of the skb if no other
>> pakcet will be sent afterwards.
>>
>> Solving this issue by introducing a new flag IFF_TX_SKB_FREE_DELAY which could
>> notify the pktgen that the device does not free skb immediately after it has
>> been sent and let it not to wait for the refcount to be one.
>>
>> Signed-off-by: Jason Wang <[email-masked]>
> Another alternative would be using skb_orphan() and skb->destructor.
> There are other cases where skb's are not freed right away.
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Hi Stephen:

Do you mean registering a skb->destructor for pktgen then set and check 
bits in skb->tx_flag?