From: Eric Dumazet <edumazet@google.com>
To: Jonathan Lemon <jonathan.lemon@gmail.com>
Cc: netdev <netdev@vger.kernel.org>, kernel-team <kernel-team@fb.com>,
Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Willem de Bruijn <willemb@google.com>,
Steffen Klassert <steffen.klassert@secunet.com>,
Saeed Mahameed <saeedm@mellanox.com>,
Maxim Mikityanskiy <maximmi@mellanox.com>,
bjorn.topel@intel.com, magnus.karlsson@intel.com,
borisp@mellanox.com, david@redhat.com
Subject: Re: [RFC PATCH v2 13/21] net/tcp: Pad TCP options out to a fixed size for netgpu
Date: Mon, 27 Jul 2020 08:19:24 -0700 [thread overview]
Message-ID: <CANn89i+nXhXzxC3C+UY0xAMFeUxZSSD8R5MP2mmttjZa+5-Hxg@mail.gmail.com> (raw)
In-Reply-To: <20200727052846.4070247-14-jonathan.lemon@gmail.com>
On Mon, Jul 27, 2020 at 12:51 AM Jonathan Lemon
<jonathan.lemon@gmail.com> wrote:
>
> From: Jonathan Lemon <bsd@fb.com>
>
> The "header splitting" feature used by netgpu doesn't actually parse
> the incoming packet header. Instead, it splits the packet at a fixed
> offset. In order for this to work, the sender needs to send packets
> with a fixed header size.
>
> Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
> ---
> net/ipv4/tcp_output.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index d8f16f6a9b02..e8a74d0f7ad2 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -438,6 +438,7 @@ struct tcp_out_options {
> u8 ws; /* window scale, 0 to disable */
> u8 num_sack_blocks; /* number of SACK blocks to include */
> u8 hash_size; /* bytes in hash_location */
> + u8 pad_size; /* additional nops for padding */
> __u8 *hash_location; /* temporary pointer, overloaded */
> __u32 tsval, tsecr; /* need to include OPTION_TS */
> struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */
> @@ -562,6 +563,17 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
> smc_options_write(ptr, &options);
>
> mptcp_options_write(ptr, opts);
> +
> +#if IS_ENABLED(CONFIG_NETGPU)
> + /* pad out options */
> + if (opts->pad_size) {
> + int len = opts->pad_size;
> + u8 *p = (u8 *)ptr;
> +
> + while (len--)
> + *p++ = TCPOPT_NOP;
> + }
> +#endif
> }
>
> static void smc_set_option(const struct tcp_sock *tp,
> @@ -826,6 +838,14 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
> opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
> }
>
> +#if IS_ENABLED(CONFIG_NETGPU)
> + /* force padding */
> + if (size < 20) {
> + opts->pad_size = 20 - size;
> + size += opts->pad_size;
> + }
> +#endif
> +
This is obviously wrong, as any kernel compiled with CONFIG_NETGPU
will fail all packetdrill tests suite.
Also the fixed 20 value is not pretty.
next prev parent reply other threads:[~2020-07-27 15:19 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200727052846.4070247-1-jonathan.lemon@gmail.com>
[not found] ` <20200727052846.4070247-4-jonathan.lemon@gmail.com>
2020-07-27 5:58 ` [RFC PATCH v2 03/21] mm: Allow DMA mapping of pages which are not online Christoph Hellwig
2020-07-27 17:08 ` Jonathan Lemon
[not found] ` <20200727052846.4070247-22-jonathan.lemon@gmail.com>
2020-07-27 7:35 ` [RFC PATCH v2 21/21] netgpu/nvidia: add Nvidia plugin for netgpu Christoph Hellwig
2020-07-27 17:00 ` Jonathan Lemon
2020-07-27 18:24 ` Christoph Hellwig
2020-07-28 1:48 ` Jonathan Lemon
2020-07-28 6:47 ` Christoph Hellwig
2020-07-28 16:05 ` Jonathan Lemon
2020-07-28 16:10 ` Christoph Hellwig
2020-07-28 18:19 ` Jason Gunthorpe
2020-07-28 21:01 ` Jonathan Lemon
2020-07-28 21:14 ` Christoph Hellwig
2020-07-28 23:38 ` Jason Gunthorpe
[not found] ` <20200727052846.4070247-14-jonathan.lemon@gmail.com>
2020-07-27 15:19 ` Eric Dumazet [this message]
2020-07-27 17:20 ` [RFC PATCH v2 13/21] net/tcp: Pad TCP options out to a fixed size " Jonathan Lemon
[not found] ` <20200727052846.4070247-16-jonathan.lemon@gmail.com>
2020-07-27 15:19 ` [RFC PATCH v2 15/21] net/tcp: add MSG_NETDMA flag for sendmsg() Eric Dumazet
2020-07-27 15:55 ` Jonathan Lemon
2020-07-27 16:09 ` Eric Dumazet
2020-07-27 17:35 ` Jonathan Lemon
2020-07-27 17:44 ` Eric Dumazet
2020-07-28 2:11 ` Jonathan Lemon
2020-07-28 2:17 ` Eric Dumazet
2020-07-28 3:08 ` Jonathan Lemon
2020-07-28 6:50 ` Christoph Hellwig
[not found] ` <20200727052846.4070247-9-jonathan.lemon@gmail.com>
2020-07-27 15:24 ` [RFC PATCH v2 08/21] skbuff: add a zc_netgpu bitflag Eric Dumazet
2020-07-27 16:59 ` Jonathan Lemon
2020-07-27 17:08 ` Eric Dumazet
2020-07-27 17:16 ` Jonathan Lemon
2020-07-27 22:44 [RFC PATCH v2 00/21] netgpu: networking between NIC and GPU/CPU Jonathan Lemon
2020-07-27 22:44 ` [RFC PATCH v2 13/21] net/tcp: Pad TCP options out to a fixed size for netgpu Jonathan Lemon
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