From: Adam Ford <aford173@gmail.com>
To: Frieder Schrempf <frieder.schrempf@kontron.de>
Cc: NXP Linux Team <linux-imx@nxp.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: i.MX8MM Ethernet TX Bandwidth Fluctuations
Date: Thu, 6 May 2021 14:20:37 -0500 [thread overview]
Message-ID: <CAHCN7xJCUtmi1eOftFq0mg28SFyt2a34q3Vy8c0fvOs5wHC-yg@mail.gmail.com> (raw)
In-Reply-To: <421cc86c-b66f-b372-32f7-21e59f9a98bc@kontron.de>
On Thu, May 6, 2021 at 9:51 AM Frieder Schrempf
<frieder.schrempf@kontron.de> wrote:
>
> Hi,
>
> we observed some weird phenomenon with the Ethernet on our i.MX8M-Mini boards. It happens quite often that the measured bandwidth in TX direction drops from its expected/nominal value to something like 50% (for 100M) or ~67% (for 1G) connections.
>
> So far we reproduced this with two different hardware designs using two different PHYs (RGMII VSC8531 and RMII KSZ8081), two different kernel versions (v5.4 and v5.10) and link speeds of 100M and 1G.
>
> To measure the throughput we simply run iperf3 on the target (with a short p2p connection to the host PC) like this:
>
> iperf3 -c 192.168.1.10 --bidir
>
> But even something more simple like this can be used to get the info (with 'nc -l -p 1122 > /dev/null' running on the host):
>
> dd if=/dev/zero bs=10M count=1 | nc 192.168.1.10 1122
>
> The results fluctuate between each test run and are sometimes 'good' (e.g. ~90 MBit/s for 100M link) and sometimes 'bad' (e.g. ~45 MBit/s for 100M link).
> There is nothing else running on the system in parallel. Some more info is also available in this post: [1].
>
> If there's anyone around who has an idea on what might be the reason for this, please let me know!
> Or maybe someone would be willing to do a quick test on his own hardware. That would also be highly appreciated!
I have seen a similar regression on linux-next on both Mini and Nano.
I thought I broke something, but it returned to normal after a reboot.
However, with a 1Gb connection, I was running at ~450 Mbs which is
consistent with what you were seeing with a 100Mb link.
adam
>
> Thanks and best regards
> Frieder
>
> [1]: https://community.nxp.com/t5/i-MX-Processors/i-MX8MM-Ethernet-TX-Bandwidth-Fluctuations/m-p/1242467#M170563
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-06 19:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 14:45 i.MX8MM Ethernet TX Bandwidth Fluctuations Frieder Schrempf
2021-05-06 14:53 ` Dave Taht
2021-05-10 12:49 ` Frieder Schrempf
2021-05-10 15:09 ` Dave Taht
2021-05-06 19:20 ` Adam Ford [this message]
2021-05-07 15:34 ` Tim Harvey
2021-05-10 12:57 ` Frieder Schrempf
2021-05-10 12:52 ` Frieder Schrempf
2021-05-10 13:10 ` Adam Ford
2021-05-12 11:58 ` Joakim Zhang
2021-05-13 12:36 ` Joakim Zhang
2021-05-17 7:17 ` Frieder Schrempf
2021-05-17 10:22 ` Joakim Zhang
2021-05-17 12:47 ` Dave Taht
2021-05-18 12:35 ` Joakim Zhang
2021-05-18 12:55 ` Frieder Schrempf
2021-05-19 7:49 ` Joakim Zhang
2021-05-19 8:10 ` Frieder Schrempf
2021-05-19 8:40 ` Joakim Zhang
2021-05-19 10:12 ` Frieder Schrempf
2021-05-19 10:47 ` Joakim Zhang
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=CAHCN7xJCUtmi1eOftFq0mg28SFyt2a34q3Vy8c0fvOs5wHC-yg@mail.gmail.com \
--to=aford173@gmail.com \
--cc=frieder.schrempf@kontron.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-imx@nxp.com \
--cc=netdev@vger.kernel.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).