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Subject: RE: [PATCH v3] ip_frag: add IPv4 fragment copy packet API
Date: Fri, 22 Jul 2022 17:52:28 +0200
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Thread-Topic: [PATCH v3] ip_frag: add IPv4 fragment copy packet API
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References: <1654784398-11315-1-git-send-email-chcchc88@163.com>
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Huichao Cai" <chcchc88@163.com>
Cc: <dev@dpdk.org>, "Stephen Hemminger" <stephen@networkplumber.org>,
 <konstantin.v.ananyev@yandex.ru>, "Olivier Matz" <olivier.matz@6wind.com>
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> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Friday, 22 July 2022 16.49
>=20
> On Fri, 22 Jul 2022 21:01:50 +0800
> Huichao Cai <chcchc88@163.com> wrote:
>=20
> > 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 =3D =
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>
>=20
> The code should just be checking that refcnt =3D=3D 1 directly.
>=20
> There are cases where sender passes a cloned mbuf.  This is =
independent
> of the fast free optimization.
>=20
> 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.