++netpfga results
This commit is contained in:
Nico Schottelius
parent
e1949d2ac3
commit
bf22fdcdb3
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@ -174,191 +174,24 @@ idomatic problem: Security issue: not checking checksums before
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% ----------------------------------------------------------------------
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\section{\label{conclusion:netpfga}NetFGPA - all HERE}
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personal note here
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stopped working
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reboot not enough
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does not respond to any packet
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tested various kernels for table debugging
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MTU limitations: 1500 according to a private mail from Salvator Galea
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cambridge / uk
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long compile process
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error prone compile process
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many dependencies
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lpm not supported!
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Netpfga live,
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Vivado
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SDNET
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xx k lines of supporting code
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Vivado installation: silent errors, infinite loop, missing libncurses5
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82k lines of code that are interdependent
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Many non critical error messages on the way
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Zero exit fatal errors
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missing / spreaded documentation
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tcpdump on local nfX doesn't work -> can only debug on other endpoint
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First card: Writing tables fails
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hardware debug shows some errors
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but hardware debug on correct card also shows some error
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Debug ioctl errors when writing table entries
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Output all ports -> port mapping documented only in a testdata script
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hwtest: Execution fails due to missing djtgcfg
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no payload accessq
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Many workarounds
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Table size 63, table size 64,
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Table entries require arguments of all possible actions, not only used
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one.
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Compile time hours
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Silent errors
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Unclear errors: broken board
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Due to the very fragile nature of the build framework from the
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NetFPGA-Live repository,
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Renaming VARIABLES in the definition of
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Reproducibility:
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hours for finding right output ports
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packet size / annotation
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Needed to debug internal parsing errors
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3x rebooting to get card working with bitstream
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Variable renaming breaks the compile process
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\begin{verbatim}
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It seems I was really mistaken for the last weeks
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If I am not totally mistaken, the following is happening with the netpfga:
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I was testing sending and receiving packets on the same computer; so I sent a packet on nfX and expected an answer on nf0, which is how I wanted to verify that the card works
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So I ran tcpdump on nf0, send a packet with ping6 and scapy on nf{0,1,2,3} (edited)
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I have never seen the switch emitting ANY packet back with tcpdump
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Now with the card connected to another host, sending neighbor solicitation, I see duplicated packets on the other host - so it seems that it might have worked all the time, just that tcpdump on nfX on the host which contains the card does not show the packets
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\end{verbatim}
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debugging generated tcl code to debug impl1 error
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Cable problems:
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\begin{verbatim}
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[ 488.265148] ixgbe 0000:02:00.0: failed to initialize because an unsupported SFP+ module type was detected.
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[ 488.265157] ixgbe 0000:02:00.0: Reload the driver after installing a supported module.
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[ 488.265605] ixgbe 0000:02:00.0: removed PHC on enp2s0f0
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\end{verbatim}
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function syntax not supported, using defines instead
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4-6 MB logfiles for a compile process.
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confusing messages
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\begin{verbatim}
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WARNING: command 'get_user_parameter' will be removed in the 2015.3
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release, use 'get_user_parameters' instead
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\end{verbatim}
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critical non critical errors
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\begin{verbatim}
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CRITICAL WARNING: [BD 41-737] Cannot set the parameter TRANSLATION_MODE on /axi_interconnect_0. It is read-only.
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\end{verbatim}
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\begin{verbatim}
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- step9 (sume simulation, the longest step) in the process calls
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"config_writes.py"
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- config_writes.py fails with a syntax error, as it is incomplete
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python code
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- config_writes.py and config_writes.sh are generated by
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gen_config_writes.py
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- gen_config_writes.py reads config_writes.txt
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- config_writes.txt is created in step 5 (sdnet simulation)
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- step 5 consists of running xsc, xelab and xsim
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- xsim (re-)generates config_writes.txt according to a watch ls -l
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on the file: ${XILINX_VIVADO}/bin/xsim --runall
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SimpleSumeSwitch_tb#work.glbl
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- it seems (by grep -r) that ./Testbench/SimpleSumeSwitch_tb.sv is
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responsible for writing config_writes.txt
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- It seems that the "task" "SV_write_control" inside that file is
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responsible for writing the content, which in turn uses
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axi4_lite_master_write_request_control
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\end{verbatim}
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\begin{verbatim}
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- Cannot easily run P4 on notebook - changes to the system very
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invasive
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- Varous compiler bugs/limitations
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- Very very deep rabbithole problems
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- Hanging/sleeping issue -- unclear whether it does something or
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not
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- Open impl_1 error with unclear reason
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- logfiles referenced that don't exist
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Run output will be captured here: /home/nico/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/hw/project/simple_sume_switch.runs/synth/runme.log
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nico@nsg-System:~/master-thesis/netpfga/log$ ls -alh /home/nico/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/hw/project/simple_sume_switch.runs/synth/runme.log
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ls: cannot access '/home/nico/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/hw/project/simple_sume_switch.runs/synth/runme.log': No such file or directory
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- even "short" compile runs taking 30m+
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control_sub_m02_data_fifo_0_synth_1: /home/nico/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/hw/project/simple_sume_switch.runs/control_sub_m02_data_fifo_0_synth_1/runme.log
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nico@nsg-System:~/master-thesis/netpfga/minip4/testdata$ less /home/nico/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/hw/project/simple_sume_switch.runs/control_sub_m02_data_fifo_0_synth_1/runme.log
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/home/nico/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/hw/project/simple_sume_switch.runs/control_sub_m02_data_fifo_0_synth_1/runme.log: No such file or directory
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- Wrong warnings: using 2018.2, getting warnings about things
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removed in 2015.3
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WARNING: command 'get_user_parameter' will be removed in the 2015.3
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release, use 'get_user_parameters' instead
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- A script/makefile generates a python script that generates a shell
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script and later then a python script. If there is a mistake in
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generating the first python script (syntax ok, but content is
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not correct) then a much later stage of the compile process will
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fail due to a syntax error in the third generated
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script. However that syntax error is not fatal in the build
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process and thus can only be seen with careful analysis of the
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logfile, which is around 700 KiB or 10k lines per compile
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process and contains 328 lines matching "error" and
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"warning".
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Most of the error and warning messages seem to be non-critical
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(even if saying they are). Then there are a variety of INFO
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messages that actually constitute ERROR messages, but are not
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flagged as such nor do they cause the build process to abort.
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\end{verbatim}
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LPM tables don't work
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match type exact - table must be at least 64 in size
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multiple reboots sometimes required for flashing
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Damaged, enlarged packets
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\begin{verbatim}
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@ -545,6 +378,14 @@ the learnings of the different layers were very much appreciated / liked
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It was a
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% ----------------------------------------------------------------------
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\section{\label{conclusion:netpfga2}NetFGPA2 - conclusion here}
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Very time intensive development due to usability problems and
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uncertainty of functionality (compare sections
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\ref{results:netpfga:usability} and \ref{results:netpfga:stability}).
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\section{todo - FIXME: remove}
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\begin{verbatim}
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***** Summary eher kurz
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100
doc/Results.tex
100
doc/Results.tex
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@ -161,13 +161,14 @@ table entries.
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Jool and tayga are supported by
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% ----------------------------------------------------------------------
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\section{\label{Results:NetPFGA}NetFPGA}
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\section{\label{results:netpfga}NetFPGA}
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The reduced feature set of the NetPFGA implementation is due to two
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factors: compile time. Between 2 to 6 hours per compile run. No
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payload checksum
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overview - general translation - not advanced features
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% ----------------------------------------------------------------------
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\subsection{\label{results:netpfga:features}Features}
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\begin{table}[htbp]
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\begin{center}\begin{minipage}{\textwidth}
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\begin{tabular}{| c | c | c |}
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@ -235,7 +236,6 @@ unsupported\footnote{To support creating payload checksums, either an
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\label{tab:p4netpfgafeatures}
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\end{center}
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\end{table}
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% ----------------------------------------------------------------------
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\subsection{\label{results:netpfga:stability}Stability}
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Two different NetPFGA cards were used during the development of the
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@ -262,15 +262,99 @@ During the development and benchmarking, the second NetFPGA card stopped to
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function properly multiple times. In both cases the card would not
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forward packets anymore. Multiple reboots (3 were usually enough)
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and multiple times reflashing the bitstream to the NetFPGA usually
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restored the intended behaviour.
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restored the intended behaviour. However due to this ``crashes'', it
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was impossible to complete a full benchmark run that would last for
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more than one hour.
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% ----------------------------------------------------------------------
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\subsection{\label{results:netpfga:performance}Performance}
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As expected, the NetFGPA card performed at near line speed and offers
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NAT64 translations at 9.28 Gbit/s.
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NAT64 translations at 9.28 Gbit/s. Single and multiple streams
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performed almost exactly identical and have been consistent through
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multiple iterations of the benchmarks.
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% ----------------------------------------------------------------------
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\subsection{\label{results:netpfga:usability}Usability}
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To use the NetFGPA, Vivado and SDNET provided by Xilinx need to be
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installed. However a bug in the installer triggers an infinite loop,
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if a certain shared library\footnote{The required shared library
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is libncurses5.} is missing on the target operating system. The
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installation program seems still to be progressing, however does never
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finish.
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While the NetFPGA card supports P4, the toolchains and supporting
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scripts are in a immature state. The compilation process consists of
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at least 9 different steps, which are interdependent\footnote{See
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source code \texttt{bin/do-all-steps.sh}.} Some of the steps generate
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shell scripts and python scripts that in turn generate JSON
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data.\footnote{One compilation step calls the script
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``config\_writes.py''. This script failed with a syntax error, as it
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contained incomplete python code. The scripts config\_writes.py
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and config\_writes.sh are generated by gen\_config\_writes.py.
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The output of the script gen\_config\_writes.py depends on the content
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of config\_writes.txt. That file is generated by the simulation
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``xsim''. The file ``SimpleSumeSwitch\_tb.sv'' contains code that is
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responsible for writing config\_writes.txt and uses a function
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named axi4\_lite\_master\_write\_request\_control for generating the
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output. This in turn is dependent on the output of a script named
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gen\_testdata.py.}
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Checksum computation
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However incorrect parsing generates syntactically incorrect
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scripts or scripts that generate incorrect output. The toolchain
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provided by the NetFGPA-P4 repository contains more than 80000 lines
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of code. The supporting scripts for setting table entries require
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setting the parameters for all possible actions, not only for the
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selected action. Supplying only the required parameters results in a
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crash of the supporting script.
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The documentation for using the NetFPGA-P4 repository is very
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distributed and does not contain a reference on how to use the
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tools. Mapping of egress ports and their metadata field are found in a
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python script that is used for generating test data.
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The compile process can take up to 6 hours and because the different
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steps are interdependent, errors in a previous stage were in our
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experiences detected hours after they happened. The resulting log
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files of the compilation process can be up to 5 MB in size. Within
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this log file various commands output references to other logfiles,
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however the referenced logfiles do not exist before or after the
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compile process.
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During the compile process various informational, warning and error
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messages are printed. However some informational messages constitute
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critical errors, while on the other hand critical errors and syntax
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errors often do not constitue a critical
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error.\footnote{F.i. ``CRITICAL WARNING: [BD 41-737] Cannot set the
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parameter TRANSLATION\_MODE on /axi\_interconnect\_0. It is
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read-only.'' is a non critical warning.}
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Also contradicting
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output is generated\footnote{While using version 2018.2, the following
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message was printed: ``WARNING: command 'get\_user\_parameter' will be removed in the 2015.3
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release, use 'get\_user\_parameters' instead''.}
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The NetFPGA kernel module provides access to virtual Linux
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devices (nf0...nf3). However tcpdump does not see any packets that are
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emitted from the switch. The only possibility to capture packets
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that are emitted from the switch is by connecting a physical cable to
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the port and capturing on the other side.
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Jumbo frames\footnote{Frames with an MTU greater than 1500 bytes.} are
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commonly used in 10 Gbit/s networks. According to
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\ref{wikipedia:_jumbo}, even many gigabit network interface card
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support jumbo frames. However according to emails on the private
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NetPFGA mailing list, the NetFPGA only supports 1500 byte frames at
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the moment and additional work is required to implement support for
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bigger frames.
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While most of the P4 language is supported on the netpfga, some key
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techniques are missing or not supported.
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\begin{itemize}
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\item Analysing / accessing payload is not supported
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\item Checksum computation over payload is not supported
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\item Using LPM tables can lead to compilation errors
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\item Depening on the match type, only certain table sizes are allowed
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\end{itemize}
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Renaming variables in the declaration of the parser or deparser lead
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to compilation errors. Function syntax is not supported. For this
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reason our implementation uses \texttt{\#define} statements instead of functions.
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Trace files
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\begin{verbatim}
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BIN
doc/Thesis.pdf
BIN
doc/Thesis.pdf
Binary file not shown.
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@ -508,7 +508,6 @@ nf3: ERROR while getting interface flags: No such device
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nico@nsg-System:~/projects/P4-NetFPGA/contrib-projects/sume-sdnet-switch/projects/minip4/simple_sume_switch/bitfiles$
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\end{verbatim}
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% ----------------------------------------------------------------------
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\section{\label{chapterB:netpfga-kernelmodule}NetFPGA Kernel module}
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After a successful flash, loading the kernel module will enable nf
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devices to appear in the operating system.
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@ -580,13 +579,15 @@ nico@nsg-System:~$
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\end{verbatim}
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% ----------------------------------------------------------------------
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\section{\label{chapterB:netpfga-nftraffic}NetFPGA misses packets on nf*}
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While the nf devices appear in the operating system, packets emitted
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by the netpfga cannot be sniffed on the nf interfaces
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directly. Instead one has to sniff packets on a physical network card
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that is connected to the specific output port.
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% ----------------------------------------------------------------------
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\section{\label{chapterB:netpfga-kernelmodule}NetFPGA Kernel module}
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%---------------------------------------------------------------------------------------------------------
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\chapter{\label{benchmark}Benchmark Logs}
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% ----------------------------------------------------------------------
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@ -135,3 +135,10 @@
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author = {Hendrik Züllig, Supervisor; Prof. Dr. Laurent Vanbever; Tutor: Tobias Bühler},
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title = {P4-Programming on an FPGA, Semester Thesis SA-2019-02},
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howpublished = {\url{https://gitlab.ethz.ch/nsg/student-projects/sa-2019-02_p4_programming_sume_netfpga/blob/master/SA-2019-02.pdf}}}
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@Misc{wikipedia:_jumbo,
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author = {Wikipedia},
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title = {Jumbo frame},
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howpublished = {\url{https://en.wikipedia.org/wiki/Jumbo_frame}},
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note = {Requested on 2019-08-15}}
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