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SubjectRe: sched_yield() on "SCHED_FIFO"
From
Date

Dear,

Thank you for your reply. However ...

The supposed action of my program depended on the Round Robin
scheduling on 1 CPU. The program produced two processes and they would
be executed alternately, because it yielded each other on 1 CPU. The
main problem is one process monopolied a CPU even if it executed
sched_yield().

On SMP two processes were executed at the same time and caused race
condition. The action would not be forecasted.

>>From: NIIBE Yutaka <gniibe@chroot.org>
>>Subject: sched_yield() on "SCHED_FIFO"
>>
>>Kuniyasu SUZAKI writes:
>> > The process is executed by super user. I was thinking this process
>> > could measure the time for context switch on the real time class
>> > "SCHED_FIFO" and it was measured on kernel 2.0.36 and Solaris. But on
>> > 2.2.5-15 the parent process didn't yield.
>>
>>Result of my environment (two CPU PII 266MHz x2).
>>
>># ./context
>>Context swicth time 6 us from 11792 to 11793
>>Context swicth time 13 us from 11793 to 11792
>>Context swicth time 4 us from 11792 to 11792
>>Context swicth time 10 us from 11792 to 11792
>>Context swicth time 3 us from 11792 to 11793
>>Context swicth time 4 us from 11793 to 11792
>>Context swicth time 5 us from 11792 to 11793
>>Context swicth time 3 us from 11793 to 11792
>>Context swicth time 5 us from 11792 to 11793
>># cat /proc/version
>>Linux version 2.2.10 (root@qwe) (gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)) #1 SMP Sat Jul 24 17:41:19 JST 1999
>>#
>>
>>Sometimes it switch to other, sometimes not.
>>--
>>Niibe Yutaka
>>

------
suzaki
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