Re: [PATCH] SCHED_FIFO and SCHED_RR scheduler fix, kernel 2.2.21

From: Bhavesh P. Davda (bhavesh@avaya.com)
Date: Fri Jun 21 2002 - 14:10:14 EST

Alan Cox wrote:
>>The 2.2.21 kernel was behaving incorrectly for SCHED_FIFO and SCHED_RR
>>scheduling.
>
>
> Looks fine but I dont want to apply behaviour changing non critical stuff
> to 2.2

Oh, no!

What's going on with the kernel community? I posted a similar fix for
the 2.4.18 kernel, and it hasn't been picked up there either.

For the 2.4.18 kernel scheduler, our 86 process application (SCHED_FIFO,
priorities 7-23, System V semaphores for priority preemption) won't even
stay up without my patch.

The 2.2.21 SCHED_FIFO behaviour is correct but slightly inefficient,
while the SCHED_RR behaviour is plain broken. What is an application
that depends on correct SCHED_RR behaviour to do in that case? There are
applications where increased latencies as a result of SCHED_RR being
broken are unacceptable. 

-- 
Bhavesh P. Davda
Avaya Inc
Room B3-B03                     E-mail : bhavesh@avaya.com
1300 West 120th Avenue          Phone  : (303) 538-4438
Westminster, CO 80234           Fax    : (303) 538-3155

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