[meta-xilinx] Ethernet Transfer Speed Question

Wed May 6 06:17:16 PDT 2015

On 05/06/2015 08:25 AM, Joe Nicholson wrote:
> Thanks, Mike, that's really helpful.  Very good news to hear that the issue has been 'fixed' in later kernels :-)
> If I can get this board to anything approaching that speed, I'll be very happy.
> 
> All I need now is to get a 3.18+ kernel build out of the meta-xilinx layer... it's still defaulting to 3.14 for this machine, even in the new Fido branch.
> 
> I see the meta-xilinx layer has a linux-yocto 3.19 recipe (3.17 in Dizzy), but only uses it for the microblaze config.
> Is it possible for me to change to the linux-yocto 3.17/19 kernel recipe for the zc702-zynq7 machine (e.g. by changing XILINX_DEFAULT_KERNEL)?  Or will this only work correctly for the microblaze?
> 
> Alternatively, would a better approach be for me to make up a completely new 3.18/19 Xilinx kernel recipe that brings in the standard Xilinx kernel and just use that?  
> I have to admit that although the meta-xilinx layer is very clever re. configuration fragments and kernel features, it's starting to confuse my (ageing) brain! 

Ideally, we just use a mainline kernel and everything works.

I'm told mainline boots on zynq, but is missing a couple of critical
features. This page shows the upstream status of drivers:

http://www.wiki.xilinx.com/Linux+Drivers

For my application, there are only two pieces missing, USB and some way
to load the fpga. I understand there are patches to resolve the USB
issue. The bigger pain point is devcfg. Vendor specific solutions for
loading fpga's will not be accepted upstream. Vendors are expected to
collaborate on a common framework called fpga_manager. It looks like
this is really close to being usable and just need a bunch of people
that need it to drown out one or two people coming up with blue sky use
case questions.

Philip

> 
> ;-)
> 
> Cheers!
> 
> Joe Nicholson
> 
> 
> -----Original Message-----
> From: Mike Looijmans [mailto:mike.looijmans at topic.nl] 
> Sent: 06 May 2015 12:49
> To: Joe Nicholson; meta-xilinx at yoctoproject.org
> Subject: Re: [meta-xilinx] Ethernet Transfer Speed Question
> 
> On 06-05-15 13:39, Joe Nicholson wrote:
>> Hi Nathan et al
>>
>> I've a question regarding data transfer speed over Ethernet using the 
>> Xilinx
>> 3.14 kernel built from the meta-xilinx layer.
>>
>> We've previously been using a 'custom' 3.9 kernel (basically a 
>> slightly customised Xilinx kernel, with a couple of new drivers… no important changes).
>>
>> We're keen to move to the standard Xilinx 3.14 kernel as built from 
>> meta-xilinx.  Our target is zc702-zynq7.
>>
>> On the 3.9 kernel, an iperf test of data transfer over the Ethernet 
>> gives a massively respectable 480Mbits/second!
>>
>> On the 3.14 kernel, however, the same test gives just 327Mbits/second.
>>
>> 327Mbits/second is OK, but still much lower than the Xilinx 3.9 kernel.
>>
>> I tried make oldconfig of the old 3.9 kernel configuration used that 
>> instead of the default config, but had the same result.
>>
>> Is it possible that the Ethernet driver has had some speed retardation 
>> in the driver recently, between 3.9 and 3.14?  Any pointers would be helpful.
>>
>> In reality I think we can probably cope with 327Mbits/second, however 
>> the customer's initial tests were on the 3.9 kernel... so I'm keen to 
>> trace the point of the speed reduction.
>>
>> On a similar issue, I tried the Daisy branch of meta-xilinx with the 
>> 3.14 kernel – it achieves only 107Mbit/second!!
>>
>> I traced this down to CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y and a few other 
>> similar debugging options being switched on by default.  These are all 
>> nicely switch off in the Dizzy branch.
>>
>> So really, I'm keen to understand why the Ethernet transfer speed of 
>> the zc702 appears to have slowed down and whether there's anything I 
>> can do to speed it back up!
>>
>> …e.g. move to Fido and a 3.17 kernel J
>>
>> Cheers!
>>
>> Joe Nicholson
>>
>>
>>
> 
> With the 3.18 kernel, iperf3 gives me the following results on a topic-miami-florida board (also a zynq, 7015, so results should be the same as for any other board):
> 
> $ iperf3 -c 192.168.80.138
> Connecting to host 192.168.80.138, port 5201 [  4] local 192.168.80.121 port 60370 connected to 192.168.80.138 port 5201
> [ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
> [  4]   0.00-1.00   sec  75.6 MBytes   634 Mbits/sec   41    348 KBytes
> [  4]   1.00-2.00   sec  75.1 MBytes   630 Mbits/sec    0    397 KBytes
> [  4]   2.00-3.00   sec  74.7 MBytes   627 Mbits/sec    0    399 KBytes
> [  4]   3.00-4.00   sec  75.6 MBytes   634 Mbits/sec    0    399 KBytes
> [  4]   4.00-5.00   sec  74.7 MBytes   627 Mbits/sec   34    321 KBytes
> [  4]   5.00-6.00   sec  76.2 MBytes   639 Mbits/sec    0    346 KBytes
> [  4]   6.00-7.00   sec  73.6 MBytes   618 Mbits/sec    0    346 KBytes
> [  4]   7.00-8.00   sec  75.3 MBytes   631 Mbits/sec    0    372 KBytes
> [  4]   8.00-9.00   sec  75.3 MBytes   632 Mbits/sec    0    375 KBytes
> [  4]   9.00-10.00  sec  77.0 MBytes   646 Mbits/sec    0    378 KBytes
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval           Transfer     Bandwidth       Retr
> [  4]   0.00-10.00  sec   753 MBytes   632 Mbits/sec   75             sender
> [  4]   0.00-10.00  sec   751 MBytes   630 Mbits/sec                  receiver
> 
> 
> $ iperf3 -c 192.168.80.138 -R
> Connecting to host 192.168.80.138, port 5201 Reverse mode, remote host 192.168.80.138 is sending [  4] local 192.168.80.121 port 60366 connected to 192.168.80.138 port 5201
> [ ID] Interval           Transfer     Bandwidth
> [  4]   0.00-1.00   sec  79.5 MBytes   667 Mbits/sec
> [  4]   1.00-2.00   sec  79.3 MBytes   665 Mbits/sec
> [  4]   2.00-3.00   sec  79.3 MBytes   665 Mbits/sec
> [  4]   3.00-4.00   sec  84.6 MBytes   710 Mbits/sec
> [  4]   4.00-5.00   sec   103 MBytes   863 Mbits/sec
> [  4]   5.00-6.00   sec   103 MBytes   865 Mbits/sec
> [  4]   6.00-7.00   sec   103 MBytes   866 Mbits/sec
> [  4]   7.00-8.00   sec   103 MBytes   866 Mbits/sec
> [  4]   8.00-9.00   sec   103 MBytes   867 Mbits/sec
> [  4]   9.00-10.00  sec   103 MBytes   866 Mbits/sec
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval           Transfer     Bandwidth       Retr
> [  4]   0.00-10.00  sec   943 MBytes   791 Mbits/sec    0             sender
> [  4]   0.00-10.00  sec   943 MBytes   791 Mbits/sec                  receiver
> 
> 
> The board is connected to the company network switch, and that's connected to the PC I'm running this on.
> 
> Apparently, something got fixed in later kernels :-)
> 
> 
> 
> Kind regards,
> 
> Mike Looijmans
> System Expert
> 
> TOPIC Embedded Products
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