From: Lorenzo Bianconi <lorenzo@kernel.org>
To: Jesper Dangaard Brouer <brouer@redhat.com>
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
Subject: Re: [PATCH v8 bpf-next 01/14] xdp: introduce mb in xdp_buff/xdp_frame
Date: Thu, 29 Apr 2021 15:54:02 +0200 [thread overview]
Message-ID: <YIq6eoS+5UZRTi/5@lore-desk> (raw)
In-Reply-To: <20210429153629.1fef2386@carbon>
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> > 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/
yes, shame on me..yesterday I recalled email from Alexei debugging the issue
reported by Magnus.
In the current approach I am testing (not posted upstream yet) I reduced the
size of xdp_mem_info as proposed by Jesper in [0] and I added a flags field
in xdp_frame/xdp_buff we can use for multiple features (e.g. multi-buff or hw csum
hints). Doing so, running xdp_rxq_info sample on ixgbe 10Gbps NIC I do not have any
performance regressions for xdp_tx or xdp_drop. Same results have been reported by
Magnus off-list on i40e (we have a 1% regression on xdp_sock tests iiuc).
I will continue working on this.
Regards,
Lorenzo
[0] https://patchwork.kernel.org/project/netdevbpf/patch/20210409223801.104657-2-mcroce@linux.microsoft.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
>
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next prev parent reply other threads:[~2021-04-29 13:54 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
2021-04-29 13:54 ` Lorenzo Bianconi [this message]
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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