[erlang-questions] What does "soft" real-time mean?

Aleksander Nycz Aleksander.Nycz@REDACTED
Fri Oct 20 15:25:15 CEST 2017


My private definition:

Hard real time -> 100% requests/jobs/processes must be completed before 

Soft real time -> N% requests/jobs/processes must be completed before 
deadline, where N < 100%,

     so we can/must accept that some jobs will not be finished on time.

And few question:

1. Erlang VM is running on Virtual Machine on bare metal?

2. What you erlang process really do? Can you show us some code?


Aleksander Nycz

W dniu 2017-10-20 o 14:00, Avinash Dhumane pisze:
> I have programmed high-frequency trading application in Erlang and 
> comparing its reaction performance in the live market with other 
> competing applications (mostly, in C).
> It has been a consistent observation that my Erlang application lags 
> substantially behind the competing applications. In fact, it never 
> matched the reaction time of the so-called "slowest" C application in 
> the market.
> The benchmark reaction time is about 5 microseconds. It is the time 
> elapsed between tick to order. That is, the difference between the 
> timestamps when I receive the tick (market event) from the mailbox of 
> my process and when I submit the TCP send call on my order.
> My process maintains the market depths of the securities and when my 
> desired price (as a function of best buyers and/or sellers on multiple 
> legs of the order) is observed, I compute the order terms and submit.
> The entire computation and communication (with the market) takes place 
> within the single process and there are no collaborating processes 
> (hence, no inter-process messaging; not even ETS). Still, the reaction 
> time is in the order of 20 to 60 microseconds - that is, nowhere 
> closer to the benchmark reaction time (5 microseconds).
> What I wish to hear from the experienced people on this forum here is 
> whether I am missing on something in my Erlang code, or should I just 
> go ahead and program in C.
> Thanks.
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Aleksander Nycz
Chief Designer
Telco_021 BSS R&D
Comarch SA
Phone:  +48 17 785 5909
Mobile: +48 691 464 275
website: www.comarch.pl

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