Re: [PATCH] Replace timer_bh with tasklet

george anzinger
2002-06-18T23:18:11Z

Richard Zidlicky wrote:
>
> On Tue, Jun 18, 2002 at 11:07:32AM -0700, george anzinger wrote:
>
> >
> > I reasoned that the timers, unlike most other I/O, directly drive the system.
> > For example, the time slice is counted down by the timer BH. By pushing the
> > timer out to ksoftirqd, running at nice 19, you open the door to a compute
> > bound task running over its time slice (admittedly this should be caught on
> > the next interrupt).
>
> I have had some problems with timers delayed up to 0.06s in 2.4 kernels,
> could that be this problem?
>
It could be. Depends on what was going on at the time. In most cases, however,
the next interrupt should cause a call to softirq and thus run the timer list. This
would seem to indicate at 20ms delay at most (first call busys softirq thru a 10ms tick
followed by recovery at the next tick).
--
George Anzinger george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml