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bfrazier_arete
Adventurer
Adventurer
964 Views
Registered: ‎09-30-2014

Network performance under Petalinux

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We have two seperate custom designed board using Zynq Ultrascale+ devices (two different size parts).  In one design the Zynq's GEM RGMII interface is connected to a TI DP83867.  The other design we tie direct to a RGMII port on an multiport ethernet switch.  In both cases, we can only get between 180 Mbps and 220 Mbps out of the Zynq Ultrascale+.  We have tried different host computers for testing to insure it isn't any software on the host and given the different phy setups, it leads us to believe it is something on the Linux (Petalinux side).  

We are looking for suggestions on how to speed up the ethernet interfaces under Linux.  Any help would be appreciated.

Both sets of hardware are being tested with Petalinux 2018.3.

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bfrazier_arete
Adventurer
Adventurer
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Registered: ‎09-30-2014

It turns out the issue was related to a little paid attention to clock setting in Vivado.  The "TIMESTAMP" clock in the clock output section of Vivado influences the CPU scheduler in Linux.  When changing it from 33.333 MHz to 100 MHz, most of my bandwidth problems were solved. 

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bfrazier_arete
Adventurer
Adventurer
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Registered: ‎09-30-2014

A little more info.  Tested using both iperf2 and iperf3 on Petalinux to external computer running iperf2 and iperf3.  

The Zynq Ultrascale+ (with both iperf2 and iperf3) achieve about 200 Mbps on transmit and 400 Mbps on receive.  Still don't know where to look.  Any help would be great.

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nanz
Moderator
Moderator
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Registered: ‎08-25-2009

HI @bfrazier_arete ,

Please check XAPP1305 on our wiki page. We also have a performance page of the design.

 


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bfrazier_arete
Adventurer
Adventurer
839 Views
Registered: ‎09-30-2014

I have looked at XAPP1305.  Not sure it really gives a good diagnostic approach.  The issue I am running into is that it appears to be some configuration issue under Linux. 

I have run the bare metal iperf test and get around 900 Mbps each direction.  So I am not sure what, under Linux may be causing degraded performance to 200 Mbps TX / 400 Mbps RX.  Any suggestions?

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bfrazier_arete
Adventurer
Adventurer
814 Views
Registered: ‎09-30-2014

It turns out the issue was related to a little paid attention to clock setting in Vivado.  The "TIMESTAMP" clock in the clock output section of Vivado influences the CPU scheduler in Linux.  When changing it from 33.333 MHz to 100 MHz, most of my bandwidth problems were solved. 

View solution in original post