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Date: Tue, 18 Jun 2002 16:17:45 -0700
From: george anzinger <george@mvista.com>
Organization: Monta Vista Software
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To: Richard Zidlicky 
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Subject: Re: [PATCH] Replace timer_bh with tasklet
References: <Pine.LNX.4.44.0206172104450.1164-100000@home.transmeta.com> <3D0F76E4.AC6EA257@mvista.com> <20020619004652.D2079@linux-m68k.org>
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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
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