25 Feb
2006
25 Feb
'06
3:44 a.m.
Hi,
I've been playing around a little with the priority thing. I would like
to understand better the way it works. Looking at the priority of jackd
(running realtime, as user, and with a RT kernel, full-preemption) I
can't figure out why if I start jackd with -P 60 (or any other number >
0) the output of chrt is always:
$ chrt -p (jackd's pid)
pid 8115's current scheduling policy: SCHED_OTHER
pid 8115's current scheduling priority: 0
I checked this in two different distros (FC4+CCRMA and Ubuntu with
custom RT kernel) and the result is the same. Is it not supposed to read:
$ chrt -p 8115
pid 8115's current scheduling policy: SCHED_FIFO (maybe?)
pid 8115's current scheduling priority: 60
I know that I can set this manually, but I'm just wondering what is the
real effect of the -P flag.
Any help will be appreciated,
Cheers!
Hector
25 Feb
25 Feb
9:29 a.m.
On Sat, 25 Feb 2006 02:44:54 -0500
Hector Centeno-Garcia <h.centeno(a)sympatico.ca> wrote:
Hi,
I've been playing around a little with the priority thing. I would like
to understand better the way it works. Looking at the priority of jackd
(running realtime, as user, and with a RT kernel, full-preemption) I
can't figure out why if I start jackd with -P 60 (or any other number >
0) the output of chrt is always:
$ chrt -p (jackd's pid)
pid 8115's current scheduling policy: SCHED_OTHER
pid 8115's current scheduling priority: 0
the relevant excerpt of "man jackd":
-P, --realtime-priority int
When running --realtime, set the scheduler priority to int.
The important part is "When running --realtime".. Usually you call jackd
like this to get a high rt prio:
jackd -R -P 70 ...
BTW: shortcut:
chrt -p `pidof jackd`
or
chrt -p `pidof "IRQ 8"`
etc..
Flo
P.S.: See my site in the signature for some more in depth info.
--
Palimm Palimm!
http://tapas.affenbande.org
4:03 p.m.
On Sat, 2006-02-25 at 02:44 -0500, Hector Centeno-Garcia wrote:
Hi,
I've been playing around a little with the priority thing. I would like
to understand better the way it works. Looking at the priority of jackd
(running realtime, as user, and with a RT kernel, full-preemption) I
can't figure out why if I start jackd with -P 60 (or any other number >
0) the output of chrt is always:
$ chrt -p (jackd's pid)
pid 8115's current scheduling policy: SCHED_OTHER
pid 8115's current scheduling priority: 0
I checked this in two different distros (FC4+CCRMA and Ubuntu with
custom RT kernel) and the result is the same. Is it not supposed to read:
$ chrt -p 8115
pid 8115's current scheduling policy: SCHED_FIFO (maybe?)
pid 8115's current scheduling priority: 60
I know that I can set this manually, but I'm just wondering what is the
real effect of the -P flag.
Any help will be appreciated,
Assuming you did start Jack with the "-R" option you are probablyk
looking at the main Jack process and that is actually SCHED_OTHER. Jack
has more threads and some of them are SCHED_FIFO.
Do this:
ls /proc/(jack's pid)/tasks
and you will see the pids of the other threads (I'm sure there must be a
more elegant way of finding this info)
A chrt of those will show something like this:
$ for pid in `ls /proc/27701/task/` ; do chrt -p $pid ; done
pid 27701's current scheduling policy: SCHED_OTHER
pid 27701's current scheduling priority: 0
pid 27702's current scheduling policy: SCHED_OTHER
pid 27702's current scheduling priority: 0
pid 27703's current scheduling policy: SCHED_OTHER
pid 27703's current scheduling priority: 0
pid 27704's current scheduling policy: SCHED_FIFO
pid 27704's current scheduling priority: 72
pid 27705's current scheduling policy: SCHED_FIFO
pid 27705's current scheduling priority: 62
And there you have the rt threads...
-- Fernando
4:23 p.m.
Fernando Lopez-Lezcano wrote:
On Sat, 2006-02-25 at 02:44 -0500, Hector
Centeno-Garcia wrote:
Aaaaah! I see! Yes, I was starting jackd with the -R flag... but I
didn't know jackd had more than one thread running at the same time.
This is what I get:
hector@Hector:~$ for pid in `ls /proc/8260/task/` ; do chrt -p $pid ; done
pid 8260's current scheduling policy: SCHED_OTHER
pid 8260's current scheduling priority: 0
pid 8261's current scheduling policy: SCHED_OTHER
pid 8261's current scheduling priority: 0
pid 8262's current scheduling policy: SCHED_FIFO
pid 8262's current scheduling priority: 80
pid 8263's current scheduling policy: SCHED_FIFO
pid 8263's current scheduling priority: 70
Thank you Fernando and Florian.
Hector.
Hi,
I've been playing around a little with the priority thing. I would like
to understand better the way it works. Looking at the priority of jackd
(running realtime, as user, and with a RT kernel, full-preemption) I
can't figure out why if I start jackd with -P 60 (or any other number >
0) the output of chrt is always:
$ chrt -p (jackd's pid)
pid 8115's current scheduling policy: SCHED_OTHER
pid 8115's current scheduling priority: 0
I checked this in two different distros (FC4+CCRMA and Ubuntu with
custom RT kernel) and the result is the same. Is it not supposed to read:
$ chrt -p 8115
pid 8115's current scheduling policy: SCHED_FIFO (maybe?)
pid 8115's current scheduling priority: 60
I know that I can set this manually, but I'm just wondering what is the
real effect of the -P flag.
Any help will be appreciated,
Assuming you did start Jack with the "-R" option you are probablyk
looking at the main Jack process and that is actually SCHED_OTHER. Jack
has more threads and some of them are SCHED_FIFO.
Do this:
ls /proc/(jack's pid)/tasks
and you will see the pids of the other threads (I'm sure there must be a
more elegant way of finding this info)
A chrt of those will show something like this:
$ for pid in `ls /proc/27701/task/` ; do chrt -p $pid ; done
pid 27701's current scheduling policy: SCHED_OTHER
pid 27701's current scheduling priority: 0
pid 27702's current scheduling policy: SCHED_OTHER
pid 27702's current scheduling priority: 0
pid 27703's current scheduling policy: SCHED_OTHER
pid 27703's current scheduling priority: 0
pid 27704's current scheduling policy: SCHED_FIFO
pid 27704's current scheduling priority: 72
pid 27705's current scheduling policy: SCHED_FIFO
pid 27705's current scheduling priority: 62
And there you have the rt threads...
-- Fernando
26 Feb
26 Feb
10:55 a.m.
Fernando Lopez-Lezcano <nando(a)ccrma.Stanford.EDU> writes:
a more elegant way of finding this info
ps -C jackd -cmL
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4 comments
4 participants
participants (4)
-
Esben Stien -
Fernando Lopez-Lezcano -
Florian Schmidt -
Hector Centeno-Garcia