21 Jun
2009
21 Jun
'09
1:09 p.m.
On Fri, Jun 19, 2009 at 2:13 PM, Lennart Poettering<mzynq(a)0pointer.de> wrote:
Heya,
Just a quick announcement:
I just moved into Fedora Rawhide a little daemon called "RealtimeKit"
which will be enabled by default, and since it is now a dependency of
PulseAudio and things work how they work this will then not only be
available in Fedora 12 but also sooner or later in the other
distributions as well, installed by default.
So what does this do? It's a simple policy daemon that hands out
SCHED_RR scheduling to normal user processes/threads that ask for it.
This appears to be a baroque mechanism designed to solve a problem
suspectible to vastly simpler solutions. Alternatively, one could see
it as a baroque mechanism designed to solve to solve a problem that
really needs a much more sophisticated solution (i.e. better
scheduling policies). Either way, it seems like something that makes
things more complex on every level, not less. Take a look at the code
in libjack/thread.c and compare and contrast what is necessary to get
a realtime thread on Linux (already) compared to OS X. You're adding a
new API for this that will not be backwards compatible beyond a kernel
change that has only just been made. I cannot imagine wanting to use
this mechanism. You also seem to have assumed that everyone agrees
that SCHED_RR is the correct policy, rather than SCHED_FIFO.
Reasonable people still disagree about this. Finally, as Chris said -
many of us are writing apps that target multiple platforms, and adding
a new dependency on non-POSIX systems like DBus in order to get done
things that are supposed to be possible with the POSIX API ... well,
it gives some of us a slightly wierd feeling at the very least.
--p