From:   "Penigalapati, Sandeep" <sandeep.penigalapati@intel.com>
To:     "Lobakin, Alexandr" <alexandr.lobakin@intel.com>,
        "intel-wired-lan@lists.osuosl.org" <intel-wired-lan@lists.osuosl.org>
CC:     Song Liu <songliubraving@fb.com>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Yonghong Song <yhs@fb.com>, Martin KaFai Lau <kafai@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        "Andrii Nakryiko" <andrii@kernel.org>,
        =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn@kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "Jakub Kicinski" <kuba@kernel.org>, KP Singh <kpsingh@kernel.org>,
        "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [Intel-wired-lan] [PATCH v4 net-next 8/9] ixgbe: don't reserve
 excessive XDP_PACKET_HEADROOM on XSK Rx to skb
Thread-Topic: [Intel-wired-lan] [PATCH v4 net-next 8/9] ixgbe: don't reserve
 excessive XDP_PACKET_HEADROOM on XSK Rx to skb
Thread-Index: AQHX7D0V/4WGMGM6NEelJP0aKGyShKxd6pWA
Date:   Tue, 11 Jan 2022 11:51:46 +0000
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References: <20211208140702.642741-1-alexandr.lobakin@intel.com>
 <20211208140702.642741-9-alexandr.lobakin@intel.com>
In-Reply-To: <20211208140702.642741-9-alexandr.lobakin@intel.com>
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>-----Original Message-----
>From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
>Alexander Lobakin
>Sent: Wednesday, December 8, 2021 7:37 PM
>To: intel-wired-lan@lists.osuosl.org
>Cc: Song Liu <songliubraving@fb.com>; Jesper Dangaard Brouer
><hawk@kernel.org>; Daniel Borkmann <daniel@iogearbox.net>; Yonghong
>Song <yhs@fb.com>; Martin KaFai Lau <kafai@fb.com>; John Fastabend
><john.fastabend@gmail.com>; Alexei Starovoitov <ast@kernel.org>; Andrii
>Nakryiko <andrii@kernel.org>; Bj=F6rn T=F6pel <bjorn@kernel.org>;
>netdev@vger.kernel.org; Jakub Kicinski <kuba@kernel.org>; KP Singh
><kpsingh@kernel.org>; bpf@vger.kernel.org; David S. Miller
><davem@davemloft.net>; linux-kernel@vger.kernel.org
>Subject: [Intel-wired-lan] [PATCH v4 net-next 8/9] ixgbe: don't reserve
>excessive XDP_PACKET_HEADROOM on XSK Rx to skb
>
>{__,}napi_alloc_skb() allocates and reserves additional NET_SKB_PAD
>+ NET_IP_ALIGN for any skb.
>OTOH, ixgbe_construct_skb_zc() currently allocates and reserves additional
>`xdp->data - xdp->data_hard_start`, which is XDP_PACKET_HEADROOM for
>XSK frames.
>There's no need for that at all as the frame is post-XDP and will go only =
to the
>networking stack core.
>Pass the size of the actual data only to __napi_alloc_skb() and don't rese=
rve
>anything. This will give enough headroom for stack processing.
>
>Fixes: d0bcacd0a130 ("ixgbe: add AF_XDP zero-copy Rx support")
>Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
>Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
>---
> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>