[PlanetCCRMA] Re: Upcoming 2.6 kernel; x86_64 (was: Other repositories)

Fernando Pablo Lopez-Lezcano nando@ccrma.Stanford.EDU
Fri May 28 11:19:01 2004

> > > do you think we can consolidate forces to have a common kernel? I would inject
> > > v4l2/i2c/lm_sensors and stuff like that that should not interfere with
> > > the usual PlanetCCRMA kernel patches.
> > 
> > Where would be those patches be? I don't want more patches :-) There are
> > now very few patches that are specific to Planet CCRMA. 
> They are at the bytesex.org and lm_sensors home pages. I will be
> spinning kernels with these and more (autofs, ntfs, maybe
> ea/acl/nfsacl) inside, and it would be nice if we could consolidate
> forces.

I agree. Let me know (perhaps off the list) which ones you would like to
try, if they patch cleanly then it should not be a problem. 

> But I am waiting for the 2.6 dust to settle, the currently shipped
> kernel will soon be updated.

I see build 383 in the testing area, I'm currently testing 391...

> Just out of curiosity, how do you measure latency and also find which
> system is causing high penalties?

There are several ways. One is to use (for 2.6.x) Takashi's version of
latencytest. It will run for a while and report nice graphs of latency
spikes with X, proc and disk i/o loads. The other is to just use some
low latency applications under a realistic load and activate xrun
reporting in alsa (available in very recent alsa cvs when you build with
--debug=full). Then just do things and check /var/log/messages for
kernel stack traces of the xruns. Hopefully kernel gurus can interpret
those and fix the problem :-)

In my current tests I'm starting to believe that xorg is at fault. The
traces that happen when xruns occur only show the interrupt stack and
nothing else, my unverified conclusion is that the thing is being
triggered by user space code, not the kernel (but that is at this point
just a guess on my part). 

> BTW is there interest for PlanetCCRMA on x86_64?

On my part, yes, but probably not before I have a clean stable and xrun free
FC2 Planet (never? :-). I do have an athlon64 machine but it is currently 
running 32 bit FC2. I did some very brief tests of 64 bit FC1 on it. 

-- Fernando