[LAD] timers

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.