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[37.116.49.210]) by smtp.gmail.com with ESMTPSA id q12sm6698885edw.81.2021.09.07.07.46.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Sep 2021 07:46:26 -0700 (PDT) Date: Tue, 7 Sep 2021 16:46:23 +0200 From: Lorenzo Bianconi To: Jesper Dangaard Brouer Cc: Lorenzo Bianconi , bpf@vger.kernel.org, netdev@vger.kernel.org, brouer@redhat.com, davem@davemloft.net, kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net, shayagr@amazon.com, john.fastabend@gmail.com, dsahern@kernel.org, echaudro@redhat.com, jasowang@redhat.com, alexander.duyck@gmail.com, saeed@kernel.org, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, tirthendu.sarkar@intel.com, toke@redhat.com Subject: Re: [PATCH v13 bpf-next 02/18] xdp: introduce flags field in xdp_buff/xdp_frame Message-ID: References: <980ad3161b9a312510c9fff76fa74e675b8f9bf3.1631007211.git.lorenzo@kernel.org> <52c78ca8-a053-2128-05a0-3aff6f84abd1@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Sdy9MTaWNHDmP6Ag" Content-Disposition: inline In-Reply-To: <52c78ca8-a053-2128-05a0-3aff6f84abd1@redhat.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --Sdy9MTaWNHDmP6Ag Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > (Minor changes requested below) >=20 > On 07/09/2021 14.35, Lorenzo Bianconi wrote: > > Introduce flags field in xdp_frame and xdp_buffer data structures > > to define additional buffer features. At the moment the only > > supported buffer feature is multi-buffer bit (mb). Multi-buffer bit > > is used to specify if this is a linear buffer (mb =3D 0) or a multi-buf= fer > > frame (mb =3D 1). In the latter case the driver is expected to initiali= ze > > the skb_shared_info structure at the end of the first buffer to link > > together subsequent buffers belonging to the same frame. > >=20 > > Acked-by: John Fastabend > > Signed-off-by: Lorenzo Bianconi > > --- > > include/net/xdp.h | 29 +++++++++++++++++++++++++++++ > > 1 file changed, 29 insertions(+) > >=20 > > diff --git a/include/net/xdp.h b/include/net/xdp.h > > index ad5b02dcb6f4..ed5ea784fd45 100644 > > --- a/include/net/xdp.h > > +++ b/include/net/xdp.h > > @@ -66,6 +66,10 @@ struct xdp_txq_info { > > struct net_device *dev; > > }; > > +enum xdp_buff_flags { > > + XDP_FLAGS_MULTI_BUFF =3D BIT(0), /* non-linear xdp buff */ > > +}; > > + > > struct xdp_buff { > > void *data; > > void *data_end; > > @@ -74,13 +78,30 @@ struct xdp_buff { > > struct xdp_rxq_info *rxq; > > struct xdp_txq_info *txq; > > u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroo= m*/ > > + u16 flags; /* supported values defined in xdp_flags */ > ^^^^^^^^^ > Variable/enum is named "xdp_buff_flags", but comment says "xdp_flags". ack, I will fix it in v14 >=20 > I think we should change flags to use u32, because xdp_buff already conta= in > 4 byte padding. (pahole output provided as help below) ack, I will fix it in v14 >=20 > > }; > > +static __always_inline bool xdp_buff_is_mb(struct xdp_buff *xdp) > > +{ > > + return !!(xdp->flags & XDP_FLAGS_MULTI_BUFF); > > +} > > + > > +static __always_inline void xdp_buff_set_mb(struct xdp_buff *xdp) > > +{ > > + xdp->flags |=3D XDP_FLAGS_MULTI_BUFF; > > +} > > + > > +static __always_inline void xdp_buff_clear_mb(struct xdp_buff *xdp) > > +{ > > + xdp->flags &=3D ~XDP_FLAGS_MULTI_BUFF; > > +} > > + > > static __always_inline void > > xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info= *rxq) > > { > > xdp->frame_sz =3D frame_sz; > > xdp->rxq =3D rxq; > > + xdp->flags =3D 0; > > } > > static __always_inline void > > @@ -122,8 +143,14 @@ struct xdp_frame { > > */ > > struct xdp_mem_info mem; > > struct net_device *dev_rx; /* used by cpumap */ > > + u16 flags; /* supported values defined in xdp_flags */ > ^^^^^^^^^ > Variable/enum is named "xdp_buff_flags", but comment says "xdp_flags". >=20 > Here (for xdp_frame) I also think we should change flags to u32, because > adding this u16 cause extra padding anyhow. (pahole output provided as he= lp > below). ack, I will fix it in v14 >=20 >=20 > > }; > > +static __always_inline bool xdp_frame_is_mb(struct xdp_frame *frame) > > +{ > > + return !!(frame->flags & XDP_FLAGS_MULTI_BUFF); > > +} > > + > > #define XDP_BULK_QUEUE_SIZE 16 > > struct xdp_frame_bulk { > > int count; > > @@ -180,6 +207,7 @@ void xdp_convert_frame_to_buff(struct xdp_frame *fr= ame, struct xdp_buff *xdp) > > xdp->data_end =3D frame->data + frame->len; > > xdp->data_meta =3D frame->data - frame->metasize; > > xdp->frame_sz =3D frame->frame_sz; > > + xdp->flags =3D frame->flags; > > } > > static inline > > @@ -206,6 +234,7 @@ int xdp_update_frame_from_buff(struct xdp_buff *xdp, > > xdp_frame->headroom =3D headroom - sizeof(*xdp_frame); > > xdp_frame->metasize =3D metasize; > > xdp_frame->frame_sz =3D xdp->frame_sz; > > + xdp_frame->flags =3D xdp->flags; > > return 0; > > } > >=20 >=20 >=20 >=20 > Details below... no need to read any further >=20 > Investigating struct xdp_frame with pahole: >=20 > $ pahole -C xdp_frame net/core/xdp.o > struct xdp_frame { > void * data; /* 0 8 */ > u16 len; /* 8 2 */ > u16 headroom; /* 10 2 */ > u32 metasize:8; /* 12: 0 4 */ > u32 frame_sz:24; /* 12: 8 4 */ > struct xdp_mem_info mem; /* 16 8 */ > struct net_device * dev_rx; /* 24 8 */ >=20 > /* size: 32, cachelines: 1, members: 7 */ > /* last cacheline: 32 bytes */ > }; >=20 >=20 > pahole -C xdp_frame net/core/xdp.o > struct xdp_frame { > void * data; /* 0 8 */ > u16 len; /* 8 2 */ > u16 headroom; /* 10 2 */ > u32 metasize:8; /* 12: 0 4 */ > u32 frame_sz:24; /* 12: 8 4 */ > struct xdp_mem_info mem; /* 16 8 */ > struct net_device * dev_rx; /* 24 8 */ > u16 flags; /* 32 2 */ >=20 > /* size: 40, cachelines: 1, members: 8 */ > /* padding: 6 */ > /* last cacheline: 40 bytes */ > }; >=20 >=20 > $ pahole -C xdp_frame net/core/xdp.o > struct xdp_frame { > void * data; /* 0 8 */ > u16 len; /* 8 2 */ > u16 headroom; /* 10 2 */ > u32 metasize:8; /* 12: 0 4 */ > u32 frame_sz:24; /* 12: 8 4 */ > struct xdp_mem_info mem; /* 16 8 */ > struct net_device * dev_rx; /* 24 8 */ > u32 flags; /* 32 4 */ >=20 > /* size: 40, cachelines: 1, members: 8 */ > /* padding: 4 */ > /* last cacheline: 40 bytes */ > }; >=20 >=20 > Details for struct xdp_buff, it already contains 4 bytes padding. >=20 > $ pahole -C xdp_buff net/core/xdp.o > struct xdp_buff { > void * data; /* 0 8 */ > void * data_end; /* 8 8 */ > void * data_meta; /* 16 8 */ > void * data_hard_start; /* 24 8 */ > struct xdp_rxq_info * rxq; /* 32 8 */ > struct xdp_txq_info * txq; /* 40 8 */ > u32 frame_sz; /* 48 4 */ > u16 flags; /* 52 2 */ >=20 > /* size: 56, cachelines: 1, members: 8 */ > /* padding: 2 */ > /* last cacheline: 56 bytes */ > }; ack, right. Regards, Lorenzo >=20 --Sdy9MTaWNHDmP6Ag Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCYTd7PAAKCRA6cBh0uS2t rBEBAP9tmgIQxl0vUSLVblsDKeUE8sOcZNKkVPb3FGvI9qIkxgD/eWDgeD9Xw4sX nMlox64EfRPyAAPvC11PTOeAOo0B/w8= =O3aw -----END PGP SIGNATURE----- --Sdy9MTaWNHDmP6Ag--