[LAT] [LAD] Patching linux

Rui Nuno Capela rncbc at rncbc.org
Mon Aug 25 15:05:07 EDT 2008

Jussi Laako wrote:
> Rui Nuno Capela wrote:
>> just tested here with NO_HZ not set in my (old) pentium4 
>> desktop.
>> it just confirmed that NO_HZ is not the culprit here. midi events are 
>> still being delivered *completely* out of time and the funny thing is 
>> it just gets somewhat better whenever you hit the pc-keyboard keys. 
>> however, it all gets back to badness once you stop pressing any key 
>> (eg. shift-key)
>> another funny thing goes that on a core2 duo T7200 laptop (x86_64) the 
>> same kernel config it runs all fine (NO_HZ=y)
> I'm kind of wondering what these have in
> /sys/devices/system/clocksource/clocksource0/current_clocksource

a) on the desktop (p4 at 2.80C), where midi timing delivery is completely 

# uname -a
Linux gamma #1 SMP PREEMPT RT Sat Aug 23 19:34:05 WEST 2008 
i686 i686 i386 GNU/Linux

# cat /sys/devices/system/clocksource/clocksource0/current_clocksource

b) on the laptop (core2 at T7200), where midi seems to work fine:

# uname -a
Linux zeta #1 SMP PREEMPT RT Sat Aug 23 19:14:58 WEST 2008 
x86_64 x86_64 x86_64 GNU/Linux

# cat /sys/devices/system/clocksource/clocksource0/current_clocksource

least to say, audio (ie. jackd) works fine on both cases. i've also 
tried to set the clocksource to hpet in a) and got no change in midi/tty 

rncbc aka Rui Nuno Capela
rncbc at rncbc.org

More information about the Linux-audio-tuning mailing list