From: Jakub Kicinski <kuba@kernel.org>
To: Mina Almasry <almasrymina@google.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH net-next v24 11/13] net: add devmem TCP documentation
Date: Tue, 3 Sep 2024 14:51:50 -0700 [thread overview]
Message-ID: <20240903145150.4ffee51b@kernel.org> (raw)
In-Reply-To: <20240831004313.3713467-12-almasrymina@google.com>
On Sat, 31 Aug 2024 00:43:11 +0000 Mina Almasry wrote:
> +The socket must be flow steered to the dmabuf bound RX queue::
> +
> + ethtool -N eth1 flow-type tcp4 ... queue 15,
nit: tailing comma here
> +Devmem payloads are inaccessible to the kernel processing the packets. This
> +results in a few quirks for payloads of devmem skbs:
> +
> +- Loopback is not functional. Loopback relies on copying the payload, which is
> + not possible with devmem skbs.
> +
> +- Software checksum calculation fails.
Speaking of which, I think we need to add readability check to
skb_checksum_help(). Shouldn't the check in __skb_checksum()
have a WARN_ON_ONCE() around it? It's impossible to return
an error from there.
> +- TCP Dump and bpf can't access devmem packet payloads.
> +
> +
> +Testing
> +=======
> +
> +More realistic example code can be found in the kernel source under
> +tools/testing/selftests/net/ncdevmem.c
looks like HTML output wraps the file path, maybe quote it as
``tools/testing/selftests/net/ncdevmem.c`` ?
next prev parent reply other threads:[~2024-09-03 21:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-31 0:43 [PATCH net-next v24 00/13] Device Memory TCP Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 01/13] netdev: add netdev_rx_queue_restart() Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 02/13] net: netdev netlink api to bind dma-buf to a net device Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 03/13] netdev: support binding dma-buf to netdevice Mina Almasry
2024-09-03 20:57 ` Jakub Kicinski
2024-08-31 0:43 ` [PATCH net-next v24 04/13] netdev: netdevice devmem allocator Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 05/13] page_pool: devmem support Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 06/13] memory-provider: dmabuf devmem memory provider Mina Almasry
2024-09-03 21:19 ` Jakub Kicinski
2024-09-09 0:21 ` Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 07/13] net: support non paged skb frags Mina Almasry
2024-09-03 21:31 ` Jakub Kicinski
2024-08-31 0:43 ` [PATCH net-next v24 08/13] net: add support for skbs with unreadable frags Mina Almasry
2024-09-03 21:40 ` Jakub Kicinski
2024-09-04 15:18 ` Mina Almasry
2024-09-04 15:29 ` Eric Dumazet
2024-08-31 0:43 ` [PATCH net-next v24 09/13] tcp: RX path for devmem TCP Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 10/13] net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 11/13] net: add devmem TCP documentation Mina Almasry
2024-09-03 21:51 ` Jakub Kicinski [this message]
2024-08-31 0:43 ` [PATCH net-next v24 12/13] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2024-08-31 0:43 ` [PATCH net-next v24 13/13] netdev: add dmabuf introspection Mina Almasry
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