Subject: Re: [linux-audio-dev] priority inversion & inheritance
From: yodaiken_AT_fsmlabs.com
Date: Fri Jul 12 2002 - 15:06:18 EEST
On Fri, Jul 12, 2002 at 10:31:14AM +0200, Peter Hanappe wrote:
> yodaiken_AT_fsmlabs.com wrote:
> > 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.
>
> This wakeup doesn't involve a call to the scheduler?
>
It does - but to the Linux scheduler.
>
>
>
>
-- --------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com
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