10 Dec
2003
10 Dec
'03
10:06 a.m.
On Wed, 2003-12-10 at 13:20, Paul Davis wrote:
look, there are only 60-80 *physical* redraws of a
monitor screen per
second. you have, therefore, *at least* 1/100 of a second before
you've "missed" a "graphics deadline". not only that, but because
of
the properties of the human visual system, missing the deadline won't
matter in anything like the way missing an audio deadline does. this
has none of the characteristics of "real time" from my perspective.
Updating 120 GTK+ sliders (as a consequence of a patch change) took
several seconds before I made the gtk thread SCHED_RR. I would call that
a missed visual deadline, No?
Notice that this sluggish behaviour is when the audio engine is near
idle, just writing silence to my ISA soundcard, which shows up as system
is using 5% cpu, user 0.1% cpu.
Now it takes a guesstimate of 0.3 seconds, perhaps a little less.
The kernel (and scheduler) is from the latest Mandrake 9.2 distribution
and I haven't yet found any notes on what patches they have applied this
time ...
now, if the audio thread is burning so much CPU time
that the GUI
doesn't get to run, its certainly a problem. but step back - is it a
problem you want to fix by raising the priority of the GUI thread so
that it steals time from the audio thread?
No and the gui doesn't steal any noticeable time. I use something like:
gui_priority = audio_priority/20;
If I am maxing out the number of running voices then there will be
nearly no graphic updates at all (which is as it happens also the
desired behaviour.)
cheers // Jens M Andreasen