Re: Raspberry Pi 3B and pitiful network speeds

From: MJ <>
Date: Mon, 21 Jun 2021 12:16:52 +1000
On 21/06/2021 7:29 am, Denis Ovsienko wrote:
> On Sun, 20 Jun 2021 15:41:05 +0100
> Denis Ovsienko <> wrote:
>> Notwithstanding your point, under right conditions NetBSD 9.2 can
>> fully utilize the RPI3B's 100Mbit/s Ethernet interface, at least in
>> one direction at a time. Hopefully that means it should be possible in
>> FreeBSD too.
> As it turns out, it is indeed possible with FreeBSD.
> In mostly-simplex tests the RPI3B managed to download at 11.4MB/s or
> to upload at 10.2MB/s. A simultaneous two-way test resulted in 7.6MB/s
> download and 7.0MB/s upload, so it looks like the 100Mb/s duplex PHY
> internally connects through a 150Mb/s simplex bottleneck or some such.
> The numbers come from a quick nc+dd test using 1000MB of pseudo-random
> data, but I remember observing similar results with iperf earlier
> (cannot remember which OS).
> The tests were done using FreeBSD 13.0-RELEASE [1] and RPI3B rev A22082
> with proper power and cooling. The SD card was a basic one. dd was
> reading from /dev/urandom and writing to /dev/null.

Well, personally, I don't like the idea of /dev/urandom, however, I can supply these for a file generated:

dd if=/dev/zero of=/tmp/test.img bs=1M count=500

This is what I have been using for testing.

Here are the figures to /dev/null:

dd if=/tmp/test.img of=/dev/null oflag=sync
1024000+0 records in
1024000+0 records out
524288000 bytes transferred in 23.079903 secs (22716213 bytes/sec)

dd if=/tmp/test.img of=/dev/null oflag=direct
1024000+0 records in
1024000+0 records out
524288000 bytes transferred in 22.398410 secs (23407376 bytes/sec)

> As a separate note, in my setup ifconfig tells "100baseTX
> <full-duplex>", which is expected for RPI3B. In the original message it
> tells "1000baseT <full-duplex>", which means the board is RPI3B+ or

Hi Denis.

Yes, you're correct. This is the 3B+. I apologize for misrepresenting it. It is also the earlier version board,

Built in 2017. I think it's version 1.1 (it's in a case, I don't feel like dismantling it).

> RPI4B. So another useful thing to do in addition to the method above
> would be to identify the model exactly and to double-check the earlier
> test results (Mb/s or MB/s).

Again, sorry, misspelling. The figures are in megabytes. So, on the Devuan, I can consistently obtain 18.x megabytes transfer using FTP or Samba. On FreeBSD it's lucky to top 10.

I have also stepped up the CPU frequency to 1400, but this makes no discernible difference.

The copying, when running Devuan, achieves the same speeds regardless of whether the input is from the SD card or an attached USB (Sandisk Extreme 128GB 3.1).

The power supply is official raspberry pi. The case has a fan, it is set for 50degC turn on (via GPIO). For FreeBSD there is not even an attached USB; nothing is on that bus.


Received on Mon Jun 21 2021 - 02:16:52 UTC

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