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JPyo0
Beginner
498 Views

Tuning Intel CPU for Hard Real-Time Application

Dear Intel Engineer,

 

I am currently working on an application that needs to guarantee real-time performance.

FYI, the processor I am using is Intel Core i7-6770HQ (it doesn't have to be this!)

 

We are trying to construct a system for the application using as follows:

1. Intel Processor

2. Preempt RT patched Linux (Ubuntu)

 

The desired cycle time for meeting real-time deadline is not determined yet (probably desired cycle time = 250 us; but the faster the better).

However, although the faster cycle time is still important, I am more concerned about minimizing or better to completely eliminating indeterminism which might be caused from C-state transition, P-state transition, Intel SpeedStep Tech., System Management Interrupt ,and etc.

 

I am following this document (link : https://www.all-electronics.de/wp-content/uploads/migrated/article-pdf/41892/432ei0111-323671.pdf)

 

So here are my questions:

 

1. Does the document provide sufficient information for realizing a system that is capable of meeting hard real-time requirements? (please provide any other information if available)

 

2. If the term "hard real-time" is ambiguous in its meaning, can you provide to what extent the intel processor can be capable of meeting hard real-time requirements? (for example, if all the required settings are done appropriately, the maximum latency that could happen is 100us at most)

 

Thanks,

Sincerely jpyo

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3 Replies
jimdempseyatthecove
Black Belt
498 Views

What are the task loads of your "hard real-time". You've specified desired interrupt latencies, but you haven't specified other requirements typical of a real time application:

computational requirements at interrupt service level
computational requirements at an elevated level
computational requirements at normal/lower levels
(IOW throughput)

Also, how many concurrent interrupts, requirements of each, ...
What is/are the interface/s?
Are you using your own driver(s)?

If you really need "hard real-time", have you considered using a dedicated embedded system for capture and "hard real-time" pre-processing, then network to your Core i7-6770HQ for the normal/lower priority background processing, data analysis, and presentation.

Jim Dempsey

JPyo0
Beginner
498 Views

Dear Mr. Dempsey,

 

First of all, thank you for the reply.

 

I will have time to answer the questions you suggested and later would like to ask you questions further.

 

Thanks again,

Sincerely Jinwon Pyo

jimdempseyatthecove
Black Belt
498 Views

I know you stated you wished to run on Core i7-6770HQ with a "Preempt RT patched Linux (Ubuntu)". This system may or may not provide what you need. Using superlative "hard" would indicate you have really time critical requirements.

The following link, while not pertaining specifically to  "Preempt RT patched Linux (Ubuntu)", will illustrate potential problems you have when your RT operating system does not provide you with full control. IOW how things happening behind the scene can muck you up.

https://www.youtube.com/watch?v=648Tx5N9Zoc

Important part starts ~1:15 into video.

Jim Dempsey

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