From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Lorenzo Bianconi <lorenzo@kernel.org>
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org,
lorenzo.bianconi@redhat.com, davem@davemloft.net,
kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net,
shayagr@amazon.com, sameehj@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, brouer@redhat.com
Subject: Re: [PATCH v8 bpf-next 01/14] xdp: introduce mb in xdp_buff/xdp_frame
Date: Thu, 29 Apr 2021 15:36:29 +0200 [thread overview]
Message-ID: <20210429153629.1fef2386@carbon> (raw)
In-Reply-To: <eef58418ab78408f4a5fbd3d3b0071f30ece2ccd.1617885385.git.lorenzo@kernel.org>
On Thu, 8 Apr 2021 14:50:53 +0200
Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> Introduce multi-buffer bit (mb) in xdp_frame/xdp_buffer data structure
> in order to specify if this is a linear buffer (mb = 0) or a multi-buffer
> frame (mb = 1). In the latter case the shared_info area at the end of the
> first buffer will be properly initialized to link together subsequent
> buffers.
>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
> include/net/xdp.h | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index a5bc214a49d9..842580a61563 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -73,7 +73,10 @@ struct xdp_buff {
> void *data_hard_start;
> struct xdp_rxq_info *rxq;
> struct xdp_txq_info *txq;
> - u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
> + u32 frame_sz:31; /* frame size to deduce data_hard_end/reserved
> + * tailroom
> + */
> + u32 mb:1; /* xdp non-linear buffer */
> };
>
> static __always_inline void
> @@ -81,6 +84,7 @@ xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info *rxq)
> {
> xdp->frame_sz = frame_sz;
> xdp->rxq = rxq;
> + xdp->mb = 0;
> }
>
> static __always_inline void
> @@ -116,7 +120,8 @@ struct xdp_frame {
> u16 len;
> u16 headroom;
> u32 metasize:8;
> - u32 frame_sz:24;
> + u32 frame_sz:23;
> + u32 mb:1; /* xdp non-linear frame */
> /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
> * while mem info is valid on remote CPU.
> */
So, it seems that these bitfield's are the root-cause of the
performance regression. Credit to Alexei whom wisely already point
this out[1] in V2 ;-)
[1] https://lore.kernel.org/netdev/20200904010705.jm6dnuyj3oq4cpjd@ast-mbp.dhcp.thefacebook.com/
> @@ -179,6 +184,7 @@ void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
> xdp->data_end = frame->data + frame->len;
> xdp->data_meta = frame->data - frame->metasize;
> xdp->frame_sz = frame->frame_sz;
> + xdp->mb = frame->mb;
> }
>
> static inline
> @@ -205,6 +211,7 @@ int xdp_update_frame_from_buff(struct xdp_buff *xdp,
> xdp_frame->headroom = headroom - sizeof(*xdp_frame);
> xdp_frame->metasize = metasize;
> xdp_frame->frame_sz = xdp->frame_sz;
> + xdp_frame->mb = xdp->mb;
>
> return 0;
> }
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2021-04-29 13:37 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 12:50 [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 01/14] xdp: introduce mb in xdp_buff/xdp_frame Lorenzo Bianconi
2021-04-08 18:17 ` Vladimir Oltean
2021-04-09 16:03 ` Lorenzo Bianconi
2021-04-29 13:36 ` Jesper Dangaard Brouer [this message]
2021-04-29 13:54 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 02/14] xdp: add xdp_shared_info data structure Lorenzo Bianconi
2021-04-08 13:39 ` Vladimir Oltean
2021-04-08 14:26 ` Lorenzo Bianconi
2021-04-08 18:06 ` kernel test robot
2021-04-08 12:50 ` [PATCH v8 bpf-next 03/14] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Lorenzo Bianconi
2021-04-08 18:19 ` Vladimir Oltean
2021-04-09 16:24 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 04/14] xdp: add multi-buff support to xdp_return_{buff/frame} Lorenzo Bianconi
2021-04-08 18:30 ` Vladimir Oltean
2021-04-09 16:28 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 05/14] net: mvneta: add multi buffer support to XDP_TX Lorenzo Bianconi
2021-04-08 18:40 ` Vladimir Oltean
2021-04-09 16:36 ` Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 06/14] net: mvneta: enable jumbo frames for XDP Lorenzo Bianconi
2021-04-08 12:50 ` [PATCH v8 bpf-next 07/14] net: xdp: add multi-buff support to xdp_build_skb_from_fram Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 08/14] bpf: add multi-buff support to the bpf_xdp_adjust_tail() API Lorenzo Bianconi
2021-04-08 19:15 ` Vladimir Oltean
2021-04-08 20:54 ` Vladimir Oltean
2021-04-09 18:13 ` Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 09/14] bpd: add multi-buffer support to xdp copy helpers Lorenzo Bianconi
2021-04-08 20:57 ` Vladimir Oltean
2021-04-09 18:19 ` Lorenzo Bianconi
2021-04-08 21:04 ` Vladimir Oltean
2021-04-14 8:08 ` Eelco Chaudron
2021-04-08 12:51 ` [PATCH v8 bpf-next 10/14] bpf: add new frame_length field to the XDP ctx Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 11/14] bpf: move user_size out of bpf_test_init Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 12/14] bpf: introduce multibuff support to bpf_prog_test_run_xdp() Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 13/14] bpf: test_run: add xdp_shared_info pointer in bpf_test_finish signature Lorenzo Bianconi
2021-04-08 12:51 ` [PATCH v8 bpf-next 14/14] bpf: update xdp_adjust_tail selftest to include multi-buffer Lorenzo Bianconi
2021-04-09 0:56 ` [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support John Fastabend
2021-04-09 20:16 ` Lorenzo Bianconi
2021-04-13 15:16 ` Eelco Chaudron
2021-04-16 14:27 ` Magnus Karlsson
2021-04-16 21:29 ` Lorenzo Bianconi
2021-04-16 23:00 ` Daniel Borkmann
2021-04-18 16:18 ` Jesper Dangaard Brouer
2021-04-19 6:20 ` Magnus Karlsson
2021-04-19 6:55 ` Lorenzo Bianconi
2021-04-20 13:49 ` Magnus Karlsson
2021-04-21 12:47 ` Jesper Dangaard Brouer
2021-04-21 14:12 ` Magnus Karlsson
2021-04-21 15:39 ` Jesper Dangaard Brouer
2021-04-22 10:24 ` Magnus Karlsson
2021-04-22 14:42 ` Jesper Dangaard Brouer
2021-04-22 15:05 ` Crash for i40e on net-next (was: [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support) Jesper Dangaard Brouer
2021-04-23 5:28 ` Magnus Karlsson
2021-04-23 16:43 ` Alexander Duyck
2021-04-25 9:45 ` Magnus Karlsson
2021-04-27 18:28 ` [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2021-04-28 7:41 ` Magnus Karlsson
2021-04-29 12:49 ` Jesper Dangaard Brouer
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