From: Jesper Dangaard Brouer <hawk@kernel.org>
To: Stanislav Fomichev <sdf@google.com>, bpf@vger.kernel.org
Cc: hawk@kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org,
haoluo@google.com, jolsa@kernel.org, kuba@kernel.org,
toke@kernel.org, willemb@google.com, dsahern@kernel.org,
magnus.karlsson@intel.com, bjorn@kernel.org,
maciej.fijalkowski@intel.com, yoong.siang.song@intel.com,
netdev@vger.kernel.org, xdp-hints@xdp-project.net
Subject: [xdp-hints] Re: [PATCH bpf-next v5 02/13] xsk: Add TX timestamp and TX checksum offload support
Date: Mon, 13 Nov 2023 14:16:49 +0100 [thread overview]
Message-ID: <c9bfe356-1942-4e49-b025-115faeec39dd@kernel.org> (raw)
In-Reply-To: <20231102225837.1141915-3-sdf@google.com>
On 11/2/23 23:58, Stanislav Fomichev wrote:
> diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
> index 2ecf79282c26..b0ee7ad19b51 100644
> --- a/include/uapi/linux/if_xdp.h
> +++ b/include/uapi/linux/if_xdp.h
> @@ -106,6 +106,41 @@ struct xdp_options {
> #define XSK_UNALIGNED_BUF_ADDR_MASK \
> ((1ULL << XSK_UNALIGNED_BUF_OFFSET_SHIFT) - 1)
>
> +/* Request transmit timestamp. Upon completion, put it into tx_timestamp
> + * field of struct xsk_tx_metadata.
> + */
> +#define XDP_TXMD_FLAGS_TIMESTAMP (1 << 0)
> +
> +/* Request transmit checksum offload. Checksum start position and offset
> + * are communicated via csum_start and csum_offset fields of struct
> + * xsk_tx_metadata.
> + */
> +#define XDP_TXMD_FLAGS_CHECKSUM (1 << 1)
> +
> +/* AF_XDP offloads request. 'request' union member is consumed by the driver
> + * when the packet is being transmitted. 'completion' union member is
> + * filled by the driver when the transmit completion arrives.
> + */
> +struct xsk_tx_metadata {
> + union {
> + struct {
> + __u32 flags;
> +
> + /* XDP_TXMD_FLAGS_CHECKSUM */
> +
> + /* Offset from desc->addr where checksumming should start. */
> + __u16 csum_start;
> + /* Offset from csum_start where checksum should be stored. */
> + __u16 csum_offset;
> + } request;
> +
> + struct {
> + /* XDP_TXMD_FLAGS_TIMESTAMP */
> + __u64 tx_timestamp;
> + } completion;
> + };
> +};
This looks wrong to me. It looks like member @flags is not avail at
completion time. At completion time, I assume we also want to know if
someone requested to get the timestamp for this packet (else we could
read garbage).
Another thing (I've raised this before): It would be really practical to
store an u64 opaque value at TX and then read it at Completion time.
One use-case is a forwarding application storing HW RX-time and
comparing this to TX completion time to deduce the time spend processing
the packet.
--Jesper
next prev parent reply other threads:[~2023-11-13 13:16 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-02 22:58 [xdp-hints] [PATCH bpf-next v5 00/13] xsk: TX metadata Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 01/13] xsk: Support tx_metadata_len Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 02/13] xsk: Add TX timestamp and TX checksum offload support Stanislav Fomichev
2023-11-13 13:16 ` Jesper Dangaard Brouer [this message]
2023-11-13 14:10 ` [xdp-hints] " Stanislav Fomichev
2023-11-13 16:29 ` Jesper Dangaard Brouer
2023-11-13 17:02 ` Stanislav Fomichev
2023-11-15 10:05 ` Jesper Dangaard Brouer
2023-11-15 13:37 ` Stanislav Fomichev
2023-11-16 14:30 ` Jesper Dangaard Brouer
2023-11-20 20:45 ` Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 03/13] tools: ynl: Print xsk-features from the sample Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 04/13] net/mlx5e: Implement AF_XDP TX timestamp and checksum offload Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 05/13] net: stmmac: Add Tx HWTS support to XDP ZC Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 06/13] xsk: Document tx_metadata_len layout Stanislav Fomichev
2023-11-05 12:45 ` [xdp-hints] " Simon Horman
2023-11-06 16:47 ` Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 07/13] xsk: Validate xsk_tx_metadata flags Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 08/13] xsk: Add option to calculate TX checksum in SW Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 09/13] selftests/xsk: Support tx_metadata_len Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 10/13] selftests/bpf: Add csum helpers Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 11/13] selftests/bpf: Add TX side to xdp_metadata Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 12/13] selftests/bpf: Convert xdp_hw_metadata to XDP_USE_NEED_WAKEUP Stanislav Fomichev
2023-11-02 22:58 ` [xdp-hints] [PATCH bpf-next v5 13/13] selftests/bpf: Add TX side to xdp_hw_metadata Stanislav Fomichev
2023-11-06 23:31 ` [xdp-hints] Re: [PATCH bpf-next v5 00/13] xsk: TX metadata Jakub Kicinski
2023-11-09 18:03 ` Alexei Starovoitov
2023-11-09 18:07 ` Stanislav Fomichev
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