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SubjectRe: How many jiffies is mmap() allowed to take in a row?

Harald Kirsch wrote:
> together with Ingo Molnar <> I am trying to
> track down the reason why a process with scheduling policy SCHED_FIFO
> and state TASK_RUNNING does not get its turn for sometimes more than 5
> jiffies. There are no other realtime processes on the system, and the
> scheduler *MUST* select this task. Conclusion: the scheduler is not
> called for more than 5 jiffies.

I've been experimenting with SCHED_FIFO, too, trying to give a sound module
player a realtime priority to prevent the music from skipping. It works fine
most of the time (music doesn't stop even if I do "startx"), but there are
functions in the kernel that take too long. One problem was easily identified:
scrolling backwards through a text with "less" spends way too much time in the
kernel. This ought to get fixed...


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