Gnyueh
Posts: 44
Joined: Sat Jun 27, 2020 8:15 am

Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Sat Jun 27, 2020 10:46 am

For RSS (Receive Side Scaling, not Really Simple Syndication), check here
https://access.redhat.com/documentation ... etwork-rss
https://docs.microsoft.com/en-us/window ... de-scaling
I have went through a lot of documents still I cannot find any useful information to determine whether rpi4 is RSS-capable or not. Neither Broadcomm nor the rpi disclose any detailed information on this. I wonder if anybody knows something about this.

Ps:
For the NIC of RPi 4, the PHY and MAC are seperated. The chip near RJ45 connector is actually the PHY, bcm54213pe and its connected to the MAC with RGMII inside the SoC. I know broadcomm provided some details of bcm54213pe but RSS-capability is determined by the MAC inside SoC, where no useful info is provided.
Kállio ínai mias óras elev́theri zoí, pará saránda khrónous, sklaviá kai filakí.

cleverca22
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Joined: Sat Aug 18, 2012 2:33 pm

Re: Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Tue Jul 28, 2020 4:55 am

here is another thread with other details for the ethernet PHY: viewtopic.php?f=29&t=277017

but there is a distinct lack of datasheets detailing how and what it can do

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2437
Joined: Thu Jul 11, 2013 2:37 pm

Re: Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Tue Jul 28, 2020 7:40 am

The MAC+driver does not support hashing of incoming packets, which are required for flow queues.

Code: Select all

pi@raspberrypi:/sys/class/net/eth0 $ sudo ethtool -x eth0
Cannot get RX ring count: Operation not supported
pi@raspberrypi:/sys/class/net/eth0 $ sudo ethtool -n eth0
Cannot get RX rings: Operation not supported
rxclass: Cannot get RX class rule count: Operation not supported
RX classification rule retrieval failed
pi@raspberrypi:/sys/class/net/eth0 $ sudo ethtool --show-nfc eth0
Cannot get RX rings: Operation not supported
rxclass: Cannot get RX class rule count: Operation not supported
RX classification rule retrieval failed
Rockets are loud.
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Gnyueh
Posts: 44
Joined: Sat Jun 27, 2020 8:15 am

Re: Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Tue Jul 28, 2020 9:03 am

jdb wrote:
Tue Jul 28, 2020 7:40 am
The MAC+driver does not support hashing of incoming packets, which are required for flow queues.

Code: Select all

pi@raspberrypi:/sys/class/net/eth0 $ sudo ethtool -x eth0
Cannot get RX ring count: Operation not supported
pi@raspberrypi:/sys/class/net/eth0 $ sudo ethtool -n eth0
Cannot get RX rings: Operation not supported
rxclass: Cannot get RX class rule count: Operation not supported
RX classification rule retrieval failed
pi@raspberrypi:/sys/class/net/eth0 $ sudo ethtool --show-nfc eth0
Cannot get RX rings: Operation not supported
rxclass: Cannot get RX class rule count: Operation not supported
RX classification rule retrieval failed
Thanks a lot for your reply! I am working on implementing SMB3 multichannel (with an additional USB3 GbE NIC with no RSS support, for SMB3 multichannel mixing RSS and Non RSS support NIC could be buggy) on my RPi4 nas and figuring this out helps a lot! The samba support for multichannel seems bad but I think it could be usable.
Last edited by Gnyueh on Tue Jul 28, 2020 9:05 am, edited 1 time in total.
Kállio ínai mias óras elev́theri zoí, pará saránda khrónous, sklaviá kai filakí.

Gnyueh
Posts: 44
Joined: Sat Jun 27, 2020 8:15 am

Re: Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Tue Jul 28, 2020 9:03 am

cleverca22 wrote:
Tue Jul 28, 2020 4:55 am
here is another thread with other details for the ethernet PHY: viewtopic.php?f=29&t=277017

but there is a distinct lack of datasheets detailing how and what it can do
Thanks a lot for your reply! That helps a lot.
Kállio ínai mias óras elev́theri zoí, pará saránda khrónous, sklaviá kai filakí.

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2437
Joined: Thu Jul 11, 2013 2:37 pm

Re: Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Tue Jul 28, 2020 9:23 am

RSS support is not required for SMB3. The NIC can handle multiple concurrent TCP connections just fine. At gigabit speeds, there is rarely any drop in throughput even with dozens of active connections.

RSS is a performance-enhancing feature in high-end/10GbE controllers where individual CPUs are assigned a queue corresponding to a particular thread, so cache thrashing/task migration is avoided. This only matters when you're processing hundreds of thousands of packets per second.
Rockets are loud.
https://astro-pi.org

Gnyueh
Posts: 44
Joined: Sat Jun 27, 2020 8:15 am

Re: Is the 1GbE NIC inside raspberry Pi 4 RSS-capable?

Tue Jul 28, 2020 9:51 am

jdb wrote:
Tue Jul 28, 2020 9:23 am
RSS support is not required for SMB3. The NIC can handle multiple concurrent TCP connections just fine. At gigabit speeds, there is rarely any drop in throughput even with dozens of active connections.

RSS is a performance-enhancing feature in high-end/10GbE controllers where individual CPUs are assigned a queue corresponding to a particular thread, so cache thrashing/task migration is avoided.
I experienced some trouble mixing RSS and non-RSS NICs when deploying SMB3 Multichannel and windows system only uses RSS capable NICs for multichannel which decrease the total usable lanes and BW. It took me a long time figuring that out with the help of a friend and that is why I am interested in this. RSS is quite common for PCIe GbE NICs while all USB based NICs dont support this.
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