Re: Feedback on preemptible kernel patch

Robert Love
2001-09-18T23:30:24Z

On Tue, 2001-09-18 at 14:18, Roger Larsson wrote:
> Do you run with the playback process reniced -N?
> It should really run with a low SCHED_FIFO or SCHED_RT policy.
> But renicing it with a negative value gives some of the benefits...
> (but you need to run as root)
> In addition to this the program might need to lock its pages down - the
> only thing I can think of that could cause several seconds delay would
> be if it has been swapped out...

Certainly giving it a higher priority should improve results (especially
with preemption), but the application should receive a fair amount of
process attention as it is, as it is TASK_RUNNABLE at all times and the
disk I/O should be routinely preempted. I am interested how much
renicing it helps, though.

Now, if it has to swap pages, that is a very good point. I tend to
blame this, or perhaps something with a long held lock (the audio
driver?) for the blips.

Its so hard to tell swap/VM issues now with all the VM work, sadly...:)

--
Robert M. Love
rml at ufl.edu
rml at tech9.net