Subject: Re: [linux-audio-dev] priority inversion & inheritance
From: yodaiken_AT_fsmlabs.com
Date: Fri Jul 12 2002 - 01:09:00 EEST
On Fri, Jul 12, 2002 at 01:40:42AM +0200, Peter Hanappe wrote:
> yodaiken_AT_fsmlabs.com wrote:
>
> >
> > For example, in RTLinux, fifos shared
> > between Linux (non-rt) processes and RT threads are asymmetric: the
> > RT thread never blocks, the non-RT thread blocks. In many cases
> > it is best to optimize the data operations and perform them under
> > a spin_lock with interrupts disabled. In RTLinux pthread_spin_lock
> > disables irqs and, in SMP also sets the lock
> > pthread_spin_lock(&myq.spin);
> > myq.tail->next = new;
> > new->next = 0;
> > myq.tail= next;
> > if(!myq.head)myq.head = new;
> > pthread_spin_unlock(&myq.spin);
>
> How do you tell a blocking non-RT thread that new data is available?
It's done automatically by a write: a write does sends a soft interrupt to
Linux and the interrupt handler does a standard wakeup on flagged fifos.
-- --------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com
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