> This is very hard to do using the mfe.c frontend. (the main reason I wrote the TMFE C++ frontend class).

Actually that's not true. Just look at 

midas/examples/mtfe/mtfe.c

this is an example for a frontend with equipment with the EQ_USER flag, which allows you easily to run a separate 
thread (or more) for event collection and processing. Of course all old-fashioned C style (code is from 2007) but it 
works.

Stefan

> > This is very hard to do using the mfe.c frontend. (the main reason I wrote the TMFE C++ frontend class).
> 
> Actually that's not true. Just look at 
> 
> midas/examples/mtfe/mtfe.c
> 
> this is an example for a frontend with equipment with the EQ_USER flag, which allows you easily to run a separate 
> thread (or more) for event collection and processing. Of course all old-fashioned C style (code is from 2007) but it 
> works.
> 
> Stefan

Thank you sir I'll give it a look.

Cheers

Isaac

We kind of agreed to rewrite the slow control system in C++. Each device will have its own driver derived from a common base class implementing the general communication. The reason we need a "system" and not only a "hand-written" driver is because we want:

- glue many device drivers together for a single equipment
- have a dedicated readout thread for every device, in order not to block other devices
- have a common error reporting scheme working with several threads
- being able to disable/enable individual devices without changing the history system each time
- having a common naming scheme for all devices (like "enforce" /Equipment/<name>/Settings/Names xxx) which is needed by the history system
- ...

Will see when we have time for that.

Stefan

Hi all,

I'm currently trying to see if I can speed up polling in a frontend I'm testing. 
Currently it seems like I can't get 'lam's to happen faster than 120 times/second. 
There must be a way to make this faster. From what I understand, changing the poll 
time (500ms by default) won't affect the frequency of polling just the 'lam' 
period.

Any suggestions?

Thanks for your help!

Isaac

Hi,

What is the actual readout time, event size?
Do you have multiple equipment and of what type if any?

PAA

> 
> I'm currently trying to see if I can speed up polling in a frontend I'm testing. 
> Currently it seems like I can't get 'lam's to happen faster than 120 times/second. 
> There must be a way to make this faster. From what I understand, changing the poll 
> time (500ms by default) won't affect the frequency of polling just the 'lam' 
> period.
> 
> Any suggestions?
> 

You could switch from the traditional midas mfe.c frontend to the C++ TMFE frontend,
where all this "lam" and "poll" business is removed.

At the moment, there are two example programs using the C++ TMFE frontend,
single threaded (progs/fetest_tmfe.cxx) and multithreaed (progs/fetest_tmfe_thread.cxx).

K.O.

> Hi all,
> 
> I'm currently trying to see if I can speed up polling in a frontend I'm testing. 
> Currently it seems like I can't get 'lam's to happen faster than 120 times/second. 
> There must be a way to make this faster. From what I understand, changing the poll 
> time (500ms by default) won't affect the frequency of polling just the 'lam' 
> period.
> 
> Any suggestions?
> 
> Thanks for your help!
> 
> Isaac

Hi,

How many equipment do you have and of what type?
What is the measured readout time of your equipment?

As you mentioned the polling time define the maximum time you spend in the in polling call before checking other equipment and system activities. But as soon as you get a LAM during the polling loop, the event is readout. The readout time of this equipment is obviously to be considered as well.

In case you have multiple equipment, the readout time of the other equipment is to be taken in account as you wont return to your polling prior the completion of them.

Something must be wrong on your side. If you take the example frontend under

midas/examples/experiment/frontend.cxx

and let it run to produce dummy events, you get about 90 Hz. This is because we have a

  ss_sleep(10);

in the read_trigger_event() routine to throttle things down. If you remove that sleep, 
you get an event rate of about 500'000 Hz. So the framework is really quick.

Probably your routine which looks for a 'lam' takes really long and should be fixed.

Stefan

> Something must be wrong on your side. If you take the example frontend under
> 
> midas/examples/experiment/frontend.cxx
> 
> and let it run to produce dummy events, you get about 90 Hz. This is because we have a
> 
>   ss_sleep(10);
> 
> in the read_trigger_event() routine to throttle things down. If you remove that sleep, 
> you get an event rate of about 500'000 Hz. So the framework is really quick.
> 
> Probably your routine which looks for a 'lam' takes really long and should be fixed.
> 
> Stefan

Sorry if I am going off-topic but, because the ss_sleep function was mentioned here, I 
would like to take the chance and report an issue that I am having.

In all my slow control frontends, the CPU usage for each frontend is close to 100%. This 
means that each frontend is monopolizing a single core. When I did some profiling, I 
noticed that 99% of the time is spent inside the ss_sleep function. Now, I would expect 
that the ss_sleep function should not require any CPU usage at all or very little.

So my two questions are:
Is this a bug or a feature?
Would you able to check/reproduce this behavior or do you need additional info from my 
side?

> Something must be wrong on your side. If you take the example frontend under
> 
> midas/examples/experiment/frontend.cxx
> 
> and let it run to produce dummy events, you get about 90 Hz. This is because we have a
> 
>   ss_sleep(10);
> 
> in the read_trigger_event() routine to throttle things down. If you remove that sleep, 
> you get an event rate of about 500'000 Hz. So the framework is really quick.
> 
> Probably your routine which looks for a 'lam' takes really long and should be fixed.
> 
> Stefan

Hi Stefan,

I should mention that I was using midas/examples/Triumf/c++/fevme.cxx. I was trying to see 
the max speed so I had the 'lam' always = 1 with nothing else to add overhead in the 
poll_event(). I was getting <200 Hz. I am assuming that this is a bug. There is no 
ss_sleep() in that function.

Thanks for your quick response!

Isaac

> > 
> > I'm currently trying to see if I can speed up polling in a frontend I'm testing. 
> > Currently it seems like I can't get 'lam's to happen faster than 120 times/second. 
> > There must be a way to make this faster. From what I understand, changing the poll 
> > time (500ms by default) won't affect the frequency of polling just the 'lam' 
> > period.
> > 
> > Any suggestions?
> > 
> 
> You could switch from the traditional midas mfe.c frontend to the C++ TMFE frontend,
> where all this "lam" and "poll" business is removed.
> 
> At the moment, there are two example programs using the C++ TMFE frontend,
> single threaded (progs/fetest_tmfe.cxx) and multithreaed (progs/fetest_tmfe_thread.cxx).
> 
> K.O.

Ok. I did not know that there was a C++ OOD frontend example in MIDAS. I'll take a look at 
it. Is there any documentation on it works?

Thanks for the support!

Isaac

> I should mention that I was using midas/examples/Triumf/c++/fevme.cxx

this is correct, the fevme frontend is written to do 100% CPU-busy polling.

there is several reasons for this:
- on our VME processors, we have 2 core CPUs, 1st core can poll the VME bus, 2nd core can run 
mfe.c and the ethernet transmitter.
- interrupts are expensive to use (in latency and in cpu use) because kernel handler has to call 
use handler, return back etc
- sub-millisecond sleep used to be expensive and unreliable (on 1-2GHz "core 1" and "core 2" 
CPUs running SL6 and SL7 era linux). As I understand, current linux and current 3+GHz CPUs can 
do reliable microsecond sleep.

K.O.

Hi all,

I am encountering a Javascript error (TypeError: client.error is undefined) when 
I transition between run states. Does anybody have an idea of what my problem 
might be? I have pasted an example of what MIDAS logs during such sequences.

Thanks for all the help!

Isaac


09:24:08.611 2021/02/10 [mhttpd,INFO] Executing script 
"~/ANIS_20210106/scripts/start_daq.sh" from ODB "/Script/Start DAQ"

09:24:13.833 2021/02/10 [Logger,LOG] Program Logger on host localhost started

09:24:28.598 2021/02/10 [fevme,LOG] Program fevme on host localhost started

09:24:33.951 2021/02/10 [mhttpd,INFO] Run #234 started

09:26:30.970 2021/02/10 [mhttpd,ERROR] [midas.cxx:4260:cm_transition_call,ERROR] 
Client "Logger" transition 2 aborted while waiting for client "fevme": 
"/Runinfo/Transition in progress" was cleared

09:26:31.015 2021/02/10 [mhttpd,ERROR] [midas.cxx:5120:cm_transition,ERROR] 
transition STOP aborted: "/Runinfo/Transition in progress" was cleared

09:27:27.270 2021/02/10 [mhttpd,ERROR] 
[system.cxx:4937:ss_recv_net_command,ERROR] timeout receiving network command 
header

09:27:27.270 2021/02/10 [mhttpd,ERROR] [midas.cxx:12262:rpc_client_call,ERROR] 
call to "fevme" on "localhost" RPC "rc_transition": timeout waiting for reply

> I am encountering a Javascript error (TypeError: client.error is undefined) when 
> I transition between run states. Does anybody have an idea of what my problem 
> might be? I have pasted an example of what MIDAS logs during such sequences.


Not enough information. Can you do this:

a) for the javascript error, if you get it every time, open the javascript debugger 
and capture the stack trace? or at least the file name, function name and line number 
where the javascript exception is thrown?

b) for the run start failure, start the run from odbedit "start now -v" or from 
"mtransition -v -d 1 START" (or "stop" as the case may be). capture the output, email 
to me directly or put in this elog here.

K.O.


> 
> Thanks for all the help!
> 
> Isaac
> 
> 
> 09:24:08.611 2021/02/10 [mhttpd,INFO] Executing script 
> "~/ANIS_20210106/scripts/start_daq.sh" from ODB "/Script/Start DAQ"
> 
> 09:24:13.833 2021/02/10 [Logger,LOG] Program Logger on host localhost started
> 
> 09:24:28.598 2021/02/10 [fevme,LOG] Program fevme on host localhost started
> 
> 09:24:33.951 2021/02/10 [mhttpd,INFO] Run #234 started
> 
> 09:26:30.970 2021/02/10 [mhttpd,ERROR] [midas.cxx:4260:cm_transition_call,ERROR] 
> Client "Logger" transition 2 aborted while waiting for client "fevme": 
> "/Runinfo/Transition in progress" was cleared
> 
> 09:26:31.015 2021/02/10 [mhttpd,ERROR] [midas.cxx:5120:cm_transition,ERROR] 
> transition STOP aborted: "/Runinfo/Transition in progress" was cleared
> 
> 09:27:27.270 2021/02/10 [mhttpd,ERROR] 
> [system.cxx:4937:ss_recv_net_command,ERROR] timeout receiving network command 
> header
> 
> 09:27:27.270 2021/02/10 [mhttpd,ERROR] [midas.cxx:12262:rpc_client_call,ERROR] 
> call to "fevme" on "localhost" RPC "rc_transition": timeout waiting for reply

> > I am encountering a Javascript error (TypeError: client.error is undefined) when 
> > I transition between run states. Does anybody have an idea of what my problem 
> > might be? I have pasted an example of what MIDAS logs during such sequences.
> 
> 
> Not enough information. Can you do this:
> 
> a) for the javascript error, if you get it every time, open the javascript debugger 
> and capture the stack trace? or at least the file name, function name and line number 
> where the javascript exception is thrown?

I've attached a screenshot of the call stack showing the file names and line numbers.

> b) for the run start failure, start the run from odbedit "start now -v" or from 
> "mtransition -v -d 1 START" (or "stop" as the case may be). capture the output, email 
> to me directly or put in this elog here.

I have also attached a screen capture of the output.

Thanks for your help as always.

Isaac

> K.O.
> 
> 
> > 
> > Thanks for all the help!
> > 
> > Isaac
> > 
> > 
> > 09:24:08.611 2021/02/10 [mhttpd,INFO] Executing script 
> > "~/ANIS_20210106/scripts/start_daq.sh" from ODB "/Script/Start DAQ"
> > 
> > 09:24:13.833 2021/02/10 [Logger,LOG] Program Logger on host localhost started
> > 
> > 09:24:28.598 2021/02/10 [fevme,LOG] Program fevme on host localhost started
> > 
> > 09:24:33.951 2021/02/10 [mhttpd,INFO] Run #234 started
> > 
> > 09:26:30.970 2021/02/10 [mhttpd,ERROR] [midas.cxx:4260:cm_transition_call,ERROR] 
> > Client "Logger" transition 2 aborted while waiting for client "fevme": 
> > "/Runinfo/Transition in progress" was cleared
> > 
> > 09:26:31.015 2021/02/10 [mhttpd,ERROR] [midas.cxx:5120:cm_transition,ERROR] 
> > transition STOP aborted: "/Runinfo/Transition in progress" was cleared
> > 
> > 09:27:27.270 2021/02/10 [mhttpd,ERROR] 
> > [system.cxx:4937:ss_recv_net_command,ERROR] timeout receiving network command 
> > header
> > 
> > 09:27:27.270 2021/02/10 [mhttpd,ERROR] [midas.cxx:12262:rpc_client_call,ERROR] 
> > call to "fevme" on "localhost" RPC "rc_transition": timeout waiting for reply

Hello,

I see this mhttpd error starting MSL-script: 
Uncaught (in promise) ReferenceError: m is not defined
at mhttpd_message (VM2848 mhttpd.js:2304)
at VM2848 mhttpd.js:2122

As I can see it does not affect work of MSL script but shows ReferenceError in 
Midas sequencer (see picture).

Could please point me how to fix this error?

Thanks.
Ruslan

Am I right in thinking that the TMFE HandlePoll function is calle once per 
PollMidas()? And what is the difference to HandleRead()?

> Am I right in thinking that the TMFE HandlePoll function is calle once per 
> PollMidas()? And what is the difference to HandleRead()?

Actually, polled equipment is not implemented yet in TMFE, as you noted, the 
internal scheduler needs to be reworked.

Anyhow, I think with modern c++ and with threads, both "periodic" and "polled" 
equipments are not strictly necessary.

Periodic equipment is effectively this:

in a thread:
while (1) {
do stuff, read data, send events
sleep
}

Polled equipment is effectively this:

in a thread:
while (1) {
if (poll()) { read data, send events }
else { sleep for a little bit }
}

Example of such code is the "bulk" equipment in progs/fetest.cxx.

But to implement the same in a single threaded environment (eliminates
problems with data locking, race conditions, etc) and to provide additional
structure to the user code, the plan is to implement polled equipment in TMFE
frontends. (periodic equipment is already implemented).

K.O.

> I see this mhttpd error starting MSL-script: 
> Uncaught (in promise) ReferenceError: m is not defined
> at mhttpd_message (VM2848 mhttpd.js:2304)
> at VM2848 mhttpd.js:2122

your line numbers do not line up with my copy of mhttpd.js. what version of midas 
do you run?

please give me the output of odbedit "ver" command (GIT revision, looks like this: 
IT revision:       Wed Feb 3 11:47:02 2021 -0800 - midas-2020-08-a-84-g78d18b1c on 
branch feature/midas-2020-12).

same info is in the midas "help" page (GIT revision).

to decipher the git revision string:

midas-2020-08-a-84-g78d18b1c means:
is commit 78d18b1c
which is 84 commits after git tag midas-2020-08-a

"on branch feature/midas-2020-12" confirms that I have the midas-2020-12 pre-
release version without having to do all the decoding above.

if you also have "-dirty" it means you changed something in the source code 
 and warranty is voided. (just joking! we can debug even modified midas source 
code)

K.O.

> 
> I have also attached a screen capture of the output.
> 

so the error is gone?


> Thanks for your help as always.
> 
> Isaac
> 
> > K.O.
> > 
> > 
> > > 
> > > Thanks for all the help!
> > > 
> > > Isaac
> > > 
> > > 
> > > 09:24:08.611 2021/02/10 [mhttpd,INFO] Executing script 
> > > "~/ANIS_20210106/scripts/start_daq.sh" from ODB "/Script/Start DAQ"
> > > 
> > > 09:24:13.833 2021/02/10 [Logger,LOG] Program Logger on host localhost started
> > > 
> > > 09:24:28.598 2021/02/10 [fevme,LOG] Program fevme on host localhost started
> > > 
> > > 09:24:33.951 2021/02/10 [mhttpd,INFO] Run #234 started
> > > 
> > > 09:26:30.970 2021/02/10 [mhttpd,ERROR] [midas.cxx:4260:cm_transition_call,ERROR] 
> > > Client "Logger" transition 2 aborted while waiting for client "fevme": 
> > > "/Runinfo/Transition in progress" was cleared
> > > 
> > > 09:26:31.015 2021/02/10 [mhttpd,ERROR] [midas.cxx:5120:cm_transition,ERROR] 
> > > transition STOP aborted: "/Runinfo/Transition in progress" was cleared
> > > 
> > > 09:27:27.270 2021/02/10 [mhttpd,ERROR] 
> > > [system.cxx:4937:ss_recv_net_command,ERROR] timeout receiving network command 
> > > header
> > > 
> > > 09:27:27.270 2021/02/10 [mhttpd,ERROR] [midas.cxx:12262:rpc_client_call,ERROR] 
> > > call to "fevme" on "localhost" RPC "rc_transition": timeout waiting for reply

> 
> I have also attached a screen capture of the output.
> 

so the error is gone?

K.O.