Though small there is non-zero runtime cost to maintain such list. That means it might be serving something that must be more beneficial. However, the order in which different mutexes are created in system will not have any pattern. So what could be that benefit? Any Ideas like useful to debug deadlocks etc.,?
Aparna, thanks for looking into this.
To make it clear I am not talking about wait queue used to control the tasks or thread that try to own a given mutexes. Let's not focus on that and don't talk about why mutexes is used in an RTOS. I know those fundamentals.
I am particularly talking about doubly linked used to manage or link several mutexes created or deleted through out the power cycle of the system.
Look up for mutex control block of ThreadX for example.
It is not needed or used for for functionality of owning a mutexes. The best I could think is for debugging purpose. Even then I couldn't think of synchronization issues that would benefit from such list. Do you know any? I am curious to learn problems that were solved with that list.
Hi Raghu,
I agree with you that the reason is probably related to debugging or optimization. It's possible that the information in the list could be used to optimize the system, for example, to tweak process priorities based on the source and/or order of the lock requests.
As to why a doubly-linked list would be used for this purpose, I honestly do not know. It does seem like overkill. However, it may also be that some software tool provided with the OS or by some third party -- an IDE or debugger, for example -- uses the doubly-linked list to provide some kind of feature to the user.
Thanks for looking into this Brett. Interesting thought on tweaking task priorities. However thee creation list is not used to track the threads trying to own the mutexes though. So,...?
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