[LAD] Patching linux 2.6.26.3

[Rui Nuno Capela]

Robin Gareus wrote:
> Rui Nuno Capela wrote:
>> Tim Goetze wrote:
>>> [Tim Goetze]
>>>
>>>> [victor]
>>>>> I was told to revert to 2.6.24.17 (not possible in my specific
>>>>> case, but there you go), in this list. Or to join the tuner's list.
>>>> http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.26.3-rt2.bz2
>>>>
>>>> worked for me.  Applied cleanly and compiled well after turning off 
>>>> some RCU-related preemption options that caused compilation errors, 
>>>> but I was in no mood to find out the exact how and why.  So far, it 
>>>> has collected a few hours of solid uptime too, but I haven't done any 
>>>> latency measuring.
>>> Update: on my laptop, the patched 2.6.26.3 kernel boots into an 
>>> endless list of tracebacks on the console.  On the main box, USB MIDI 
>>> input is only read as soon as a key is pressed on the USB keyboard 
>>> (the one with the letters, not the MIDI one ...).  USB MIDI out is 
>>> broken, too.  So it's back to the old version.
>>>
>> ah, it seems i'm not alone.
> 
> hehe , nice try. We won't let you go that easily ;)
> 
>> i'm currently recovering myself from schock after returning from 
>> vacation and while trying 2.6.26.x-rt for the rentrýe it all seemed to 
>> work fine except omg... midi timing is a wreck, specially wrt.alsa 
>> sequencer. event delivery is completely fubar. i mean, completely. true 
>> showstopper, whatever :(
> 
>> cacophony seems to be the right word to express what it is.
> 
>> however, didn't had the time to check whether NOHZ is at stake. i'm 
>> certainly going back to 2.6.25.x-rt where things are still sane and 
>> pleasant for a while.
> 
>> btw, having NOHZ=y (aka tickless kernel) has been the norm here, since 
>> its inception
> 
> CONFIG_NO_HZ=y - same norm here; with good results iff it works.
> 

just tested 2.6.23.3-rt3 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)

byee
-- 
rncbc aka Rui Nuno Capela
rncbc at rncbc.org