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SubjectRe: 2.2.1 scheduler behavior

On Fri, 19 Feb 1999, Rik van Riel wrote:

> On 18 Feb 1999, Claude Gamache wrote:
> > We have an application made up of 15 processes that interact
> > through shared memories and sockets. Each process computes for a
> > few milliseconds and then pass its data to the next one (a
> > pipeline computation scheme).
> [SNIP]
> > It looks as if the use of the RTC at high frequencies causes the
> > Kernel scheduler to be executed more often.
> Andrea, Ingo?

Just to add my 2c, I noticed the same thing with a little module
that repeatedly adds itself to tq_immediate and exports a count to
/proc. It executes either two or four times the interrupt frequency
depending on whether an application selects on rtc or does a blocking
read. Isn't that simply due to scheduling on the interrupt and syscall

But I noticed something else curious. When I had apm compiled in
along with CONFIG_APM_CPU_IDLE, the task would execute between
30000 to 40000 times per second! Removing apm it went back
the more "normal" 400 to 600.

Just wondering is this the expected behavior?

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