[PlanetCCRMA] another fc3 kernel on the edge (2.6.12-0.9.rdt)

[Fernando Lopez-Lezcano]

On Wed, 2005-07-06 at 18:17, Peter Lutek wrote:
> Peter Lutek wrote:
> > Fernando Lopez-Lezcano wrote:
> > >> On Sat, 2005-07-02 at 00:12, Peter Lutek wrote:
> >>>>> Peter Lutek wrote:
> >>>>>> tried it on my FC3 laptop.... boots ok, but qjackctl sends the 
> >>>> machine into a hard lock trying to start jack.
> >>>>
> >>>> hmmm......guess i should try starting jack from the command line, 
> >>>> eh? but i'm loathe to be forced to hit that power switch again!
> >>>>>
> >>> ok... with this new kernel and alsa stuff, i tried the following 
> >>> command line to start jack:
> >>>
> >>> jackd -v -R -d alsa -C -P -dhw:1 -r44100 -p128 -n2 -D
> >>>
> >>> piping the output to a file didn't work because the machine locks up 
> >>> tight as a drum -- can't even get to another login terminal. however, 
> >>> i did observe the following in the jack output:
> >>>
> >>> required capabilities not available
> >>> capabilities: =
> >>>
> >>> and then later (after all the i/o channels of my multiface appear to 
> >>> have come up):
> >>>
> >>> 4935 waiting for signals
> >>>
> >>> ...and then it just sits there, completely locked up.
> >>> (the number at the beginning of that line changes each time i try it)
> >>>
> >>> if anyone out there has any idea what's going on, please let me know!
> >>
> >> Sounds like a kernel bug (lockup).
> >> Not much I can do, but there is yet another edge kernel should you wish
> >> to try it. In the usual place (planetedge repository) for fc3 and in
> >> planetcore for fc4, version is 2.6.12-0.12.rdt, "apt-get install
> >> planetccrma-core-edge" should get it as usual...
> >>> 
> > turns out the issues i was having with my 2.6.11 system were due to the 
> > multi-band eq plugin (in steve harris' package). i decided to try this 
> > new 2.6.12-0.12 kernel anyway, and it does not lock up for me as 
> > 2.6.12-0.9 did.
> > 
> > so far, if i avoid the multi-band plugin, it's looking rock solid for me!
> > 
> > thanks again, fernando!
> 
> ugh.... i spoke too soon. i've just experienced my stopped playback and 
> xrun "storm" issue which i described over in lau, on a session which 
> doesn't contain the multi-band plugin.
> 
> i'm assuming this is not kernel-related, because i saw this on 2.6.11 as 
> well.
> 
> back to the drawing board.

Check your cpu usage. If the cpu usage suddenly goes up and you starting
getting a lot of xruns then that smells like a denormal problem (is your
cpu an Intel one?). Denormals are very tiny numbers that are handled
differently in hardware (they eat up a lot of cpu compared with "normal"
numbers). An example I had to fix was freeverb, stop feeding it signal
and the internal numbers would eventually decay into denormals and there
goes the whole cpu, entirely crunching numbers that are 300dB down from
full scale....

-- Fernando