Subj : Re: mutex&threads
To   : comp.programming.threads
From : loic-dev
Date : Mon Mar 21 2005 03:08 am

Hello Valerio,


> I've a big problem with a porting of linux on a mips board (based on
IDT
> R4K). The problem is about mutex, threads and scheduling.

which Linux kernel / libpthreads versions are you using?


> I've monitored the duration of my routine at priority 99 (A)
(attached to
> the interrupt via device driver) and I'm very surpriesed to see that,
> sometimes, but often, my routine duration is about 20ms. Normally my
> routine duration is about 100us (micro sec).

How did you monitor the duration of your routine?


> I don't understand this problem about linux scheduling, because I
think that
> when my thread at priority 99 (A) preempts the thread at priority 98
(B)
> after mutex lock then treads A stops on mutex, then starts the thread
B
> that unlocks the mutex and, I hope, the scheduler runs again my
thread A at
> priority 99... so, after this, I should have the dalay of the for
cycle of
> 1000 in the thread B that is around few micro seconds, not tens of
ms. Is
> this correct?

Theoritically yes. But there might be some scheduling latency here...


Cheers,
Loic.

.