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Message-ID: <PH0PR11MB583042FF9988C2B445B7B06FD89B9@PH0PR11MB5830.namprd11.prod.outlook.com> Date: Wed, 12 Apr 2023 01:31:19 +0000 From: "Song, Yoong Siang" <yoong.siang.song@...el.com> To: Stanislav Fomichev <sdf@...gle.com> CC: Giuseppe Cavallaro <peppe.cavallaro@...com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, Jose Abreu <joabreu@...opsys.com>, "David S . Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, "Jakub Kicinski" <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexei Starovoitov <ast@...nel.org>, "Daniel Borkmann" <daniel@...earbox.net>, Jesper Dangaard Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, Alexander Duyck <alexanderduyck@...com>, "Ong, Boon Leong" <boon.leong.ong@...el.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-stm32@...md-mailman.stormreply.com" <linux-stm32@...md-mailman.stormreply.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "bpf@...r.kernel.org" <bpf@...r.kernel.org>, "xdp-hints@...-project.net" <xdp-hints@...-project.net> Subject: RE: [PATCH net-next 3/4] net: stmmac: add Rx HWTS metadata to XDP receive pkt On Tuesday, April 11, 2023 12:25 AM, Stanislav Fomichev <sdf@...gle.com> wrote: >On 04/10, Song Yoong Siang wrote: >> Add receive hardware timestamp metadata support via kfunc to XDP >> receive packets. >> >> Signed-off-by: Song Yoong Siang <yoong.siang.song@...el.com> >> --- >> drivers/net/ethernet/stmicro/stmmac/stmmac.h | 1 + >> .../net/ethernet/stmicro/stmmac/stmmac_main.c | 24 +++++++++++++++++-- >> 2 files changed, 23 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h >> b/drivers/net/ethernet/stmicro/stmmac/stmmac.h >> index ac8ccf851708..760445275da8 100644 >> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h >> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h >> @@ -94,6 +94,7 @@ struct stmmac_rx_buffer { >> >> struct stmmac_xdp_buff { >> struct xdp_buff xdp; >> + ktime_t rx_hwts; >> }; >> >> struct stmmac_rx_queue { >> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c >> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c >> index f7bbdf04d20c..ca183fbfde85 100644 >> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c >> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c >> @@ -5307,6 +5307,8 @@ static int stmmac_rx(struct stmmac_priv *priv, int >limit, u32 queue) >> } >> } >> > >[..] > >> + stmmac_get_rx_hwtstamp(priv, p, np, &ctx.rx_hwts); > >Do we want to pay this cost for every packet? > >The preferred alternative is to store enough state in the stmmac_xdp_buff so we >can get to this data from stmmac_xdp_rx_timestamp. > >I haven't read this code, but tentatively: >- move priv, p, np into stmmac_xdp_buff, assign them here instead of > calling stmmac_get_rx_hwtstamp >- call stmmac_get_rx_hwtstamp from stmmac_xdp_rx_timestamp with the > stored priv, p, np > >That would ensure that we won't waste the cycles pulling out the rx timestamp >for every packet if the higher levels / users don't care. > >Would something like this work? Hi Stanislav Fomichev, Thanks for your comments. Original stmmac_rx() function is already calling stmmac_get_rx_hwtstamp() for every packet. This patch move the calling of stmmac_get_rx_hwtstamp() earlier so that rx timestamp is available before running bpf_prog_run_xdp(). So, i think no additional cost introduced here. Any other thoughts? Furthermore, stmmac_get_rx_hwtstamp() will check whether hw timestamp is enabled in driver and available in the descriptor before getting the hw timestamp. > >> + >> if (!skb) { >> unsigned int pre_len, sync_len; >> >> @@ -5315,7 +5317,7 @@ static int stmmac_rx(struct stmmac_priv *priv, >> int limit, u32 queue) >> >> xdp_init_buff(&ctx.xdp, buf_sz, &rx_q->xdp_rxq); >> xdp_prepare_buff(&ctx.xdp, page_address(buf->page), >> - buf->page_offset, buf1_len, false); >> + buf->page_offset, buf1_len, true); >> >> pre_len = ctx.xdp.data_end - ctx.xdp.data_hard_start - >> buf->page_offset; >> @@ -5411,7 +5413,7 @@ static int stmmac_rx(struct stmmac_priv *priv, >> int limit, u32 queue) >> >> shhwtstamp = skb_hwtstamps(skb); >> memset(shhwtstamp, 0, sizeof(struct skb_shared_hwtstamps)); >> - stmmac_get_rx_hwtstamp(priv, p, np, &shhwtstamp->hwtstamp); Original stmmac_get_rx_hwtstamp() function is called here. Thanks & Regards Siang >> + shhwtstamp->hwtstamp = ctx.rx_hwts; >> >> stmmac_rx_vlan(priv->dev, skb); >> skb->protocol = eth_type_trans(skb, priv->dev); @@ -7071,6 >+7073,22 >> @@ void stmmac_fpe_handshake(struct stmmac_priv *priv, bool enable) >> } >> } >> >> +static int stmmac_xdp_rx_timestamp(const struct xdp_md *_ctx, u64 >> +*timestamp) { >> + const struct stmmac_xdp_buff *ctx = (void *)_ctx; >> + >> + if (ctx->rx_hwts) { >> + *timestamp = ctx->rx_hwts; >> + return 0; >> + } >> + >> + return -ENODATA; >> +} >> + >> +const struct xdp_metadata_ops stmmac_xdp_metadata_ops = { >> + .xmo_rx_timestamp = stmmac_xdp_rx_timestamp, >> +}; >> + >> /** >> * stmmac_dvr_probe >> * @device: device pointer >> @@ -7178,6 +7196,8 @@ int stmmac_dvr_probe(struct device *device, >> >> ndev->netdev_ops = &stmmac_netdev_ops; >> >> + ndev->xdp_metadata_ops = &stmmac_xdp_metadata_ops; >> + >> ndev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | >NETIF_F_IPV6_CSUM | >> NETIF_F_RXCSUM; >> ndev->xdp_features = NETDEV_XDP_ACT_BASIC | >NETDEV_XDP_ACT_REDIRECT >> | >> -- >> 2.34.1 >>
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