From: "Rafał Miłecki" <zajec5@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Lunn <andrew@lunn.ch>,
Alexander Lobakin <alexandr.lobakin@intel.com>,
Network Development <netdev@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Russell King <linux@armlinux.org.uk>,
Felix Fietkau <nbd@nbd.name>,
"openwrt-devel@lists.openwrt.org"
<openwrt-devel@lists.openwrt.org>,
Florian Fainelli <f.fainelli@gmail.com>
Subject: Re: Optimizing kernel compilation / alignments for network performance
Date: Tue, 10 May 2022 14:51:28 +0200 [thread overview]
Message-ID: <46a4a91b-e068-4b87-f707-f79486b23f67@gmail.com> (raw)
In-Reply-To: <CAK8P3a1nR2VHYJsTy6aCz9qeZD0M2PYNyYgVwUj=_TOJvwCLwg@mail.gmail.com>
On 6.05.2022 11:44, Arnd Bergmann wrote:
> On Fri, May 6, 2022 at 10:55 AM Rafał Miłecki <zajec5@gmail.com> wrote:
>> On 6.05.2022 10:45, Arnd Bergmann wrote:
>>> On Fri, May 6, 2022 at 9:44 AM Rafał Miłecki <zajec5@gmail.com> wrote:
>>>> With
>>>> echo 1 > /sys/class/net/eth0/queues/rx-0/rps_cpus
>>>> my NAT speeds were jumping between 2 speeds:
>>>> 284 Mbps / 408 Mbps
>>>
>>> Can you try using 'numactl -C' to pin the iperf processes to
>>> a particular CPU core? This may be related to the locality of
>>> the user process relative to where the interrupts end up.
>>
>> I run iperf on x86 machines connected to router's WAN and LAN ports.
>> It's meant to emulate end user just downloading from / uploading to
>> Internet some data.
>>
>> Router's only task is doing masquarade NAT here.
>
> Ah, makes sense. Can you observe the CPU usage to be on
> a particular core in the slow vs fast case then?
With echo 0 > /sys/class/net/eth0/queues/rx-0/rps_cpus
NAT speed was verying between:
a) 311 Mb/s (CPUs load: 100% + 0%)
b) 408 Mb/s (CPUs load: 100% + 62%)
With echo 1 > /sys/class/net/eth0/queues/rx-0/rps_cpus
NAT speed was verying between:
a) 290 Mb/s (CPUs load: 100% + 0%)
b) 410 Mb/s (CPUs load: 100% + 63%)
With echo 2 > /sys/class/net/eth0/queues/rx-0/rps_cpus
NAT speed was stable:
a) 372 Mb/s (CPUs load: 100% + 26%)
b) 375 Mb/s (CPUs load: 82% + 100%)
With echo 3 > /sys/class/net/eth0/queues/rx-0/rps_cpus
NAT speed was verying between:
a) 293 Mb/s (CPUs load: 100% + 0%)
b) 332 Mb/s (CPUs load: 100% + 17%)
c) 374 Mb/s (CPUs load: 81% + 100%)
d) 442 Mb/s (CPUs load: 100% + 75%)
After some extra debugging I found a reason for varying CPU usage &
varying NAT speeds.
My router has a single swtich so I use two VLANs:
eth0.1 - LAN
eth0.2 - WAN
(VLAN traffic is routed to correct ports by switch). On top of that I
have "br-lan" bridge interface briding eth0.1 and wireless interfaces.
For all that time I had /sys/class/net/br-lan/queues/rx-0/rps_cpus set
to 3. So bridge traffic was randomly handled by CPU 0 or CPU 1.
So if I assign specific CPU core to each of two interfaces, e.g.:
echo 1 > /sys/class/net/eth0/queues/rx-0/rps_cpus
echo 2 > /sys/class/net/br-lan/queues/rx-0/rps_cpus
things get stable.
With above I get stable 419 Mb/s (CPUs load: 100% + 64%) on every iperf
session.
next prev parent reply other threads:[~2022-05-10 12:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 12:04 Optimizing kernel compilation / alignments for network performance Rafał Miłecki
2022-04-27 12:56 ` Alexander Lobakin
2022-04-27 17:31 ` Rafał Miłecki
2022-04-29 14:18 ` Rafał Miłecki
2022-04-29 14:49 ` Arnd Bergmann
2022-05-05 15:42 ` Rafał Miłecki
2022-05-05 16:04 ` Andrew Lunn
2022-05-05 16:46 ` Felix Fietkau
2022-05-06 7:47 ` Rafał Miłecki
2022-05-06 12:42 ` Andrew Lunn
2022-05-10 10:29 ` Rafał Miłecki
2022-05-10 14:09 ` Dave Taht
2022-05-10 19:15 ` Dave Taht
2022-05-06 7:44 ` Rafał Miłecki
2022-05-06 8:45 ` Arnd Bergmann
2022-05-06 8:55 ` Rafał Miłecki
2022-05-06 9:44 ` Arnd Bergmann
2022-05-10 12:51 ` Rafał Miłecki [this message]
2022-05-10 13:19 ` Arnd Bergmann
2022-05-10 11:23 ` Rafał Miłecki
2022-05-10 13:18 ` Arnd Bergmann
2022-05-08 9:53 ` Rafał Miłecki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=46a4a91b-e068-4b87-f707-f79486b23f67@gmail.com \
--to=zajec5@gmail.com \
--cc=alexandr.lobakin@intel.com \
--cc=andrew@lunn.ch \
--cc=arnd@arndb.de \
--cc=f.fainelli@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux@armlinux.org.uk \
--cc=nbd@nbd.name \
--cc=netdev@vger.kernel.org \
--cc=openwrt-devel@lists.openwrt.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).