Tag Archives: multi-threading

The three ‘No’s of sequential consistency

Glennan Carnie

Glennan Carnie

Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.

He specialises in C++, UML, software modelling, Systems Engineering and process development.
Glennan Carnie

Latest posts by Glennan Carnie (see all)

In the previous article we looked at the memory consistency problem that occurs when writing multi-threaded code for modern multi-processor systems.

In this article is we’ll have a look at how we can solve the sequential consistency problem and restore some sanity to our programming

Posted in ARM, C/C++ Programming, Cortex | Tagged , , , , , , | Leave a comment

Debunking priority

Glennan Carnie

Glennan Carnie

Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.

He specialises in C++, UML, software modelling, Systems Engineering and process development.
Glennan Carnie

Latest posts by Glennan Carnie (see all)

Before I start, a disclaimer:

For the purposes of this article I’m limiting the discussion to even-driven systems on priority-based, pre-emptive operating systems, on single processors.

I’m using the word task to mean ‘unit of execution’ or ‘unit of schedulability’, in preference to thread or process. I’m ignoring the different OS memory models.

There seems to be a fair amount of misunderstanding about the concept of priority in concurrent programming:

Priority means one task is more ’important’ than another.
Priority allows one task to […]

Posted in Design Issues, RTOS | Tagged , , , , , | Leave a comment