 13 Feb 2020, Marius Koeppel, Forum, Writting Midas Events via FPGAs
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Dear all,
we creating Midas events directly inside a FPGA and send them off via DMA into the PC RAM. For reading out this RAM via Midas the FPGA sends as a pointer |
 13 Feb 2020, Stefan Ritt, Forum, Writting Midas Events via FPGAs
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The rb_xxx functions are (thoroughly tested) robust against high data rate given that you use them as intended:
1) Once you create the ring buffer via rb_create(), specify the maximum event size (midas event, not bank size!). Later there is not protection any more, |
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13 Feb 2020, Stefan Ritt, Forum, Writting Midas Events via FPGAs
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The rb_xxx function are (thoroughly tested!) robust against high data rate given that you use them as intended:
1) Once you create the ring buffer via rb_create(), specify the maximum event size (overall event size, not bank size!). Later there is no protection any |
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14 Feb 2020, Konrad Briggl, Forum, Writting Midas Events via FPGAs
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Hello Stefan,
is there a difference for the later data processing (after writing the ring buffer blocks)
if we write single events or multiple in one rb_get_wp - memcopy - rb_increment_wp cycle?
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14 Feb 2020, Stefan Ritt, Forum, Writting Midas Events via FPGAs
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rb_xxx functions are midas event agnostic. The receiving side in mfe.cxx (lines 1418 in receive_trigger_event) however pulls one event at a time. If you
have some inconsistency I would put some debugging code there.
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20 Feb 2020, Konstantin Olchanski, Forum, Writting Midas Events via FPGAs
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> rb_xxx functions are midas event agnostic. The receiving side in mfe.cxx (lines 1418 in receive_trigger_event) however pulls one event at a time. If you
> have some inconsistency I would put some debugging code there.
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20 Feb 2020, Marius Koeppel, Forum, Writting Midas Events via FPGAs
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We also agree and found the problem now. Since we build everything (MIDAS Event Header, Bank Header, Banks etc.) in the FPGA we had some struggle with
the MIDAS data format (http://lmu.web.psi.ch/docu/manuals/bulk_manuals/software/midas195/html/AppendixA.html). We thought that only the MIDAS Event needs |
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20 Feb 2020, Stefan Ritt, Forum, Writting Midas Events via FPGAs
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Actually the cause of all of the is a real bug in the midas functions. We want each bank 8-byte aligned, so there is code in bk_close like:
midas.cxx:14788:
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21 Feb 2020, Konstantin Olchanski, Forum, Writting Midas Events via FPGAs
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Hi, Stefan - is this our famous 64-bit misalignement? Where we have each alternating bank aligned and misaligned at 64 bits? Without changing the data
format, one can always store data in 64-bit aligned banks by inserting a dummy banks between real banks:
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21 Feb 2020, Konstantin Olchanski, Forum, Writting Midas Events via FPGAs
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> We also agree and found the problem now.
Good. what was wrong?
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21 Feb 2020, Stefan Ritt, Forum, Writting Midas Events via FPGAs
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> Hi, Stefan - is this our famous 64-bit misalignement? Where we have each alternating bank aligned and misaligned at 64 bits? Without changing the data
> format, one can always store data in 64-bit aligned banks by inserting a dummy banks between real banks:
>
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23 Feb 2020, Marius Koeppel, Forum, Writting Midas Events via FPGAs
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> > We also agree and found the problem now.
>
> Good. what was wrong?
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12 Dec 2021, Marius Koeppel, Bug Report, Writting MIDAS Events via FPGAs 
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Dear all,
in 13 Feb 2020 to 21 Feb 2020 we had a talk about how I try to create MIDAS events directly on a FPGA and
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26 Jan 2022, Konstantin Olchanski, Bug Report, Writting MIDAS Events via FPGAs
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> today I did not get the data into MIDAS.
Any error messages printed by the frontend? any error message in midas.log? core dumps? crashes?
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26 Jan 2022, Marius Koeppel, Bug Report, Writting MIDAS Events via FPGAs
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> Any error messages printed by the frontend? any error message in midas.log? core dumps? crashes?
> I do not understand what you mean by "did not get the data into midas". You create events
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26 Jan 2022, Konstantin Olchanski, Bug Report, Writting MIDAS Events via FPGAs
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>
> > Any error messages printed by the frontend? any error message in midas.log? core dumps? crashes?
> > I do not understand what you mean by "did not get the data into midas". You create events
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26 Jan 2022, Marius Koeppel, Bug Report, Writting MIDAS Events via FPGAs
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> If you are connected locally (no mserver), I want to know the value returned by bm_send_event(). Simplest
> if you edit mfe.c and everywhere it calls bm_send_event() and rpc_send_event(), print the returned value.
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28 Jan 2022, Stefan Ritt, Bug Report, Writting MIDAS Events via FPGAs
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I finally got the dummy program working. There were several issues:
- event_buffer_size was defined as 10000 * 32 MB = 320 GB, exceeding the RAM of the computer
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16 Feb 2022, Marius Koeppel, Bug Report, Writting MIDAS Events via FPGAs
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I just came back to this and started to use the dummy frontend.
Unfortunately, I have a problem during run cycles:
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03 Mar 2022, Stefan Ritt, Bug Report, Writting MIDAS Events via FPGAs
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> Starting the frontend and starting a run works fine -> seeing events with mdump and also on the web GUI.
> But when I stop the run and try to start the next run the frontend is sending no events anymore.
> It get stuck at line 221 (if (status == DB_TIMEOUT)).
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