Re: [jazzplusplus-devel] Starting jackd on Mandriva

[Kevin C. <ke...@co...>]

On 19 May 2008 at 9:21, "D.B. Moore" <db...@ho...> wrote:

> I wanted this stuff to be part of the docs anyway, because Bob already 
> raised this in another thread....but right here, it appears to report Pete's
> situation back to him. I looked at your kernel config, these are the relevant
> sections in your linux resulting in the qsynth error message ;
> 
> //my comments
> 
> 
> CONFIG_HZ_1000=y
> CONFIG_HZ=1000
> 
> //you DO have the right HZ
> 
> 
> # CONFIG_PREEMPT_NONE is not set
> CONFIG_PREEMPT_VOLUNTARY=y
> # CONFIG_PREEMPT is not set
> # CONFIG_PREEMPT_BKL is not set
> 
> //I haven't looked at qsynth code, but my guess is the above
> //is the show-stopper. 'VOLUNTARY' = normal 'Desktop' preemption
> //'Low-latency Desktop requires CONFIG_PREEMPT=y (as I do)
> 
> 
> CONFIG_DEFAULT_IOSCHED="cfq"
> 
> //not actually how sure this one matters...I use DEADLINE
> //myself as I'm more interested in linear performance
> 
> 
> CONFIG_TICK_ONESHOT=y
> CONFIG_NO_HZ=y
> CONFIG_HIGH_RES_TIMERS=y
> 
> //I don't use the 'dynamic ticks' stuff
> //I believe one needs the HIGH_RES_TIMER set like you have

Ah, the messy kernel timer stuff.  That doesn't have to be 
distribution specific.  It's an issue that the kernel developers 
pushed onto MIDI users, opting for a lower timer resolution in order 
to improve laptop battery life.  I think they were going to try and 
make it a runtime option, but I haven't followed it.  But, I do know 
that Mandriva inherited the 250Hz junk and I get timer resolution 
warnings when I start up Rosegarden4.  Rosegarden runs fine, even 
with the lower timer resolution.  I imagine it might have problems 
quantizing anything I played live, but I haven't tried that.

Cheers...


--
Kevin