[LAD] timers

[Emanuel Rumpf]

Hi

I'm confused about all the timers.

There is:
- system timer
- hpet (high precision event timer)
- hr-timer (high resolution timer)
- rtc (real time clock)
- cyclic (what's that? a coded loop?)
- anything else ?


What is the relation of all these ?
Which hardware devices are actually used by those ?
Which is the prefered timer for sequencing ? hr-timer / rtc ?

Some timers can be opened only once ?
For example if jackdbus is using hr-timer, no other application can too ?
But applications need to use the same timer  in order to sync - right ?
Which concepts exist to share a certain timer ?
How to verify if a timer is working ?
Is there tool that would help ?
Opening the hr-timer with rosegarden freezes my whole system here,
what could cause that ?

Thanks



Related to my sytem:


I get:
------

$ lsmod | grep rtc
rtc_cmos                9680  0
rtc_core               16784  1 rtc_cmos
rtc_lib                 2844  1 rtc_core



But the following command doesn't list any rtc-timer (is that
expected, what to do ?):
-------------------------------------------------------------
$ cat /proc/asound/timers
G0: system timer : 1000.000us (10000000 ticks)
G3: HR timer : 0.001us (1000000000 ticks)
  Client sequencer queue 2 : running
  Client sequencer queue 0 : running
P0-0-0: PCM playback 0-0-0 : SLAVE
P0-0-1: PCM capture 0-0-1 : SLAVE
P0-1-0: PCM playback 0-1-0 : SLAVE
P0-2-1: PCM capture 0-2-1 : SLAVE
P1-3-0: PCM playback 1-3-0 : SLAVE
P2-0-0: PCM playback 2-0-0 : SLAVE
P2-0-1: PCM capture 2-0-1 : SLAVE
P5-0-1: PCM capture 5-0-1 : SLAVE

$ ls /dev/rtc* -lh
lrwxrwxrwx 1 root root       4 2009-11-05 17:13 /dev/rtc -> rtc0
crw-rw---- 1 root audio 251, 0 2009-11-05 17:13 /dev/rtc0

$ uname -a
Linux 2.6.31-rt11-e1 #1 SMP PREEMPT RT  Oct 27 CET 2009 i686 GNU/Linux Debian



--
E.R.