From: Samuel Holland <samuel@sholland.org>
To: Xiaozhou Liu <liuxiaozhou@bytedance.com>,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: zhangyongsu@bytedance.com, wangdongdong.6@bytedance.com,
duanxiongchun@bytedance.com, wireguard@lists.zx2c4.com,
wangjian@bytedance.com
Subject: Re: Single CPU core bottleneck caused by high site-to-site traffic
Date: Fri, 8 Mar 2019 18:16:33 -0600 [thread overview]
Message-ID: <d1e49305-3748-9f8f-737d-1a4eeb495b5a@sholland.org> (raw)
In-Reply-To: <20190302042419.gv3ldcooxzbf4veq@bytedancedeMacBook-Air.local>
On 03/01/19 22:24, Xiaozhou Liu wrote:
> Hi Jason and the list,
>
> Here at our corporate network we run some inner site-to-site VPNs using
> WireGuard. Thanks for giving out such a beautiful software to the world.
>
> Recently we encountered some noticeable network latency during peak traffic
> time. Although the traffic is pretty huge, the WireGuard box is far from
> running out of any of its resources: CPU, memory, network bandwidth, etc.
>
> It turns out that the bottleneck is caused by the single UDP connection
> between the sites, which cannot be routed to different CPU cores by RSS
> on receiving. The total CPU usage is not high, but one of the cores can
> reach 100%.
>
> Maybe we can improve this by:
>
> embedding more endpoints in one peer so that the VPN tunnel can run
> multiple UDP flows instead of one. Hence, the single huge UDP flow is
> effectively broken down to some smaller ones which can be received by
> multiple queues of the NIC and then later processed by more CPU cores.
> It will not break current users because the single UDP connection is
> still provided as the default configuration.
While a native solution would be nice, you should be able to do this today with
nftables. Dynamically rewrite the port number on a portion of the outgoing
packets, and redirect that additional port to the main port on the receive side.
This (untested) is based on the examples in the nftables wiki[1]:
$ nft add rule nat output ip daddr $OTHER_PEER udp dport $MAIN_PORT \
dnat to $PEER : numgen inc mod 2 map { \
0 : $MAIN_PORT ,\
1 : $ALT_PORT \
}
$ nft add rule nat prerouting ip daddr $MY_IP udp dport $ALT_PORT \
redirect to $MAIN_PORT
[1]: https://wiki.nftables.org/wiki-nftables/index.php/Load_balancing
> It is also possible to set up multiple wg interfaces and more connections
> explicitly. But it would make the network administration much more complex.
>
> We are planning to make a working demo of this idea but we would like to
> hear from you first.
>
> Any idea or comment is appreciated.
>
>
> Thanks,
> Xiaozhou
Regards,
Samuel
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prev parent reply other threads:[~2019-03-09 0:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 19:05 [PATCH 1/2] build/tools: Add support for Haiku Alexander von Gluck IV
2019-02-28 19:05 ` [PATCH 2/2] genkey: v2. Be more aggressive in the search for entropy Alexander von Gluck IV
2019-03-01 19:54 ` [PATCH 1/2] build/tools: Add support for Haiku Jason A. Donenfeld
2019-03-02 4:24 ` Single CPU core bottleneck caused by high site-to-site traffic Xiaozhou Liu
2019-03-09 0:16 ` Samuel Holland [this message]
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