From: Martin KaFai Lau <kafai@fb.com>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: David Ahern <dsahern@gmail.com>, <io-uring@vger.kernel.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Jonathan Lemon <jonathan.lemon@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Willem de Bruijn <willemb@google.com>,
Eric Dumazet <edumazet@google.com>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [RFC 00/12] io_uring zerocopy send
Date: Wed, 1 Dec 2021 13:51:57 -0800 [thread overview]
Message-ID: <20211201215157.kgqd5attj3dytfgs@kafai-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <974b266e-d224-97da-708f-c4a7e7050190@gmail.com>
On Wed, Dec 01, 2021 at 08:15:28PM +0000, Pavel Begunkov wrote:
> On 12/1/21 19:20, David Ahern wrote:
> > On 12/1/21 12:11 PM, Pavel Begunkov wrote:
> > > btw, why a dummy device would ever go through loopback? It doesn't
> > > seem to make sense, though may be missing something.
> >
> > You are sending to a local ip address, so the fib_lookup returns
> > RTN_LOCAL. The code makes dev_out the loopback:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/net/ipv4/route.c#n2773
>
> I see, thanks. I still don't use the skb_orphan_frags_rx() hack
> and it doesn't go through the loopback (for my dummy tests), just
> dummy_xmit() and no mention of loopback in perf data, see the
> flamegraph. Don't know what is the catch.
>
> I'm illiterate of the routing paths. Can it be related to
> the "ip route add"? How do you get an ipv4 address for the device?
I also bumped into the udp-connect() => ECONNREFUSED (111) error from send-zc.
because I assumed no server is needed by using dummy. Then realized
the cover letter mentioned msg_zerocopy is used as the server.
Mentioning just in case someone hits it also.
To tx out dummy, I did:
#> ip a add 10.0.0.1/24 dev dummy0
#> ip -4 r
10.0.0.0/24 dev dummy0 proto kernel scope link src 10.0.0.1
#> ./send-zc -4 -D 10.0.0.(2) -t 10 udp
ip -s link show dev dummy0
2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 65535 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/ether 82:0f:e0:dc:f7:e6 brd ff:ff:ff:ff:ff:ff
RX: bytes packets errors dropped missed mcast
0 0 0 0 0 0
TX: bytes packets errors dropped carrier collsns
140800890299 2150397 0 0 0 0
next prev parent reply other threads:[~2021-12-01 21:53 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 15:18 [RFC 00/12] io_uring zerocopy send Pavel Begunkov
2021-11-30 15:18 ` [RFC 01/12] skbuff: add SKBFL_DONT_ORPHAN flag Pavel Begunkov
2021-11-30 15:18 ` [RFC 02/12] skbuff: pass a struct ubuf_info in msghdr Pavel Begunkov
2021-11-30 15:18 ` [RFC 03/12] net/udp: add support msgdr::msg_ubuf Pavel Begunkov
2021-11-30 15:18 ` [RFC 04/12] net: add zerocopy_sg_from_iter for bvec Pavel Begunkov
2021-11-30 15:18 ` [RFC 05/12] net: optimise page get/free for bvec zc Pavel Begunkov
2021-12-01 19:20 ` Jonathan Lemon
2021-12-01 20:17 ` Pavel Begunkov
2021-11-30 15:18 ` [RFC 06/12] io_uring: add send notifiers registration Pavel Begunkov
2021-11-30 15:18 ` [RFC 07/12] io_uring: infrastructure for send zc notifications Pavel Begunkov
2021-11-30 15:18 ` [RFC 08/12] io_uring: wire send zc request type Pavel Begunkov
2021-11-30 15:18 ` [RFC 09/12] io_uring: add an option to flush zc notifications Pavel Begunkov
2021-11-30 15:18 ` [RFC 10/12] io_uring: opcode independent fixed buf import Pavel Begunkov
2021-11-30 15:18 ` [RFC 11/12] io_uring: sendzc with fixed buffers Pavel Begunkov
2021-11-30 15:19 ` [RFC 12/12] io_uring: cache struct ubuf_info Pavel Begunkov
2021-12-01 3:10 ` [RFC 00/12] io_uring zerocopy send David Ahern
2021-12-01 15:32 ` Pavel Begunkov
2021-12-01 17:57 ` David Ahern
2021-12-01 19:11 ` Pavel Begunkov
2021-12-01 19:20 ` David Ahern
2021-12-01 20:15 ` Pavel Begunkov
2021-12-01 21:51 ` Martin KaFai Lau [this message]
2021-12-01 22:35 ` David Ahern
2021-12-01 23:07 ` Martin KaFai Lau
2021-12-01 23:18 ` Pavel Begunkov
2021-12-02 15:48 ` Pavel Begunkov
2021-12-02 17:40 ` Martin KaFai Lau
2021-12-01 20:42 ` Pavel Begunkov
2021-12-01 14:31 ` Pavel Begunkov
2021-12-01 17:49 ` David Ahern
2021-12-01 19:59 ` Pavel Begunkov
2021-12-01 18:10 ` Willem de Bruijn
2021-12-01 19:59 ` Pavel Begunkov
2021-12-01 20:29 ` Pavel Begunkov
2021-12-02 0:36 ` Willem de Bruijn
2021-12-02 16:25 ` Pavel Begunkov
2021-12-02 0:32 ` Willem de Bruijn
2021-12-02 16:45 ` Pavel Begunkov
2021-12-02 21:25 ` Willem de Bruijn
2021-12-03 16:19 ` Pavel Begunkov
2021-12-03 16:30 ` Willem de Bruijn
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