At 2022-07-22 23:52:28, "Morten Brørup" <mb@smartsharesystems.com> wrote:
>> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
>> Sent: Friday, 22 July 2022 16.49
>> 
>> On Fri, 22 Jul 2022 21:01:50 +0800
>> Huichao Cai <chcchc88@163.com> wrote:
>> 
>> > Some NIC drivers support MBUF_FAST_FREE(Device supports optimization
>> > for fast release of mbufs. When set application must guarantee that
>> > per-queue all mbufs comes from the same mempool and has refcnt = 1)
>> > offload. In order to adapt to this offload function, add this API.
>> > Add some test data for this API.
>> >
>> > Signed-off-by: Huichao Cai <chcchc88@163.com>
>> 
>> The code should just be checking that refcnt == 1 directly.
>> 
>> There are cases where sender passes a cloned mbuf.  This is independent
>> of the fast free optimization.
>> 
>> Similar to what Linux kernel does with skb_cow().
>
>Olivier just confirmed that MBUF_FAST_FREE requires that the mbufs are direct and non-segmented, although these requirements are not yet documented.
>
>This means that you should not generate segmented mbufs with this patch. I don't know what to do instead; probably fail with an appropriate errno.

When the bnxt driver sends mbuf, it will take the mbuf segments apart and hang it to the tx_buf_ring, so there is no mbuf segments when it is released.Does this mean that there can be mbuf segments?