[Ardour-Users] The future?

[Mark Knecht]

On Fri, Aug 13, 2010 at 11:40 AM, Fernando Lopez-Lezcano
<nando at ccrma.stanford.edu> wrote:
> On Thu, 2010-08-12 at 15:24 +0100, Nick Murtagh wrote:
>> On 12 August 2010 15:11, david headon <davidheadonuk at yahoo.co.uk> wrote:
>> >   I'm not sure why. I find similar non-functionality with the Ubuntu repos
>> > and their 'realtime' kernel..
>> > Longer boot times, and no discernible performance improvements...
>> > Perhaps even worse!
>>
>> Here's what ubuntu do to create "their" kernel:
>>
>> http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/lucid/linux-rt/lucid/annotate/head:/debian/patches/series
>>
>> Very little. It's basically vanilla. Are the other distros patching
>> their realtime kernels more than this?
>
> The Planet CCRMA rt kernel is applied on top of (usually) bleeding edge
> versions of the Fedora kernel builds. So it has whatever fixes Fedora
> adds - but only those that allow the rt patch to patch cleanly - plus
> the rt patch, and almost nothing else.
>
> The kernel configuration (also important) is vanilla Fedora plus the
> usual rt tweaks.
>
> (BTW, the current version on fc13 is 2.6.33.7-rt29)
>
> As to why different distros rt kernels act differently I don't really
> really know. I would imagine it would be very difficult to do a
> scientific comparison, too many variables. One caveat to take into
> account is that performance not only depends on the rt kernel itself.
> The interrupt priorities have to be properly prioritized (thanks to
> Rui's rtirq script plus a correct configuration). And Jack itself has to
> run at the right rt priority level as well (below the soundcard irq
> priority but above everything else). If those priorities don't match up
> correctly the performance will not be as good.
>
> Plus, of course, the hardware you run on will also make a difference.
>
> -- Fernando
>
>
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>

Good to see you Fernando.

I suspect there are more ways to do that than people on Earth if you include

(all possible kernel patches) * (different kernel config options).

The Gentoo pro-audio overlay rt-sources is simply vanilla-sources +
the rt-patches. No Gentoo kernel patches like gentoo-sources.

c2stable ~ # emerge rt-sources
Calculating dependencies... done!

>>> Verifying ebuild manifests

>>> Emerging (1 of 1) sys-kernel/rt-sources-2.6.33.7-r29 from proaudio

<SNIP>

 * CPV:  sys-kernel/rt-sources-2.6.33.7-r29
 * REPO: proaudio
 * USE:  amd64 elibc_glibc kernel_linux multilib userland_GNU
>>> Preparing to unpack ...
>>> Unpacking source...
>>> Unpacking linux-2.6.33.tar.bz2 to /var/tmp/portage/sys-kernel/rt-sources-2.6.33.7-r29/work
 * Applying patch-2.6.33.7.patch (-p0+) ...
                                      [ ok ]
 * Applying patch-2.6.33.7-rt29.bz2 ...
                                      [ ok ]
>>> Source unpacked in /var/tmp/portage/sys-kernel/rt-sources-2.6.33.7-r29/work
>>> Compiling source in /var/tmp/portage/sys-kernel/rt-sources-2.6.33.7-r29/work/linux-2.6.33.7-rt29 ...
>>> Source compiled.
>>> Test phase [not enabled]: sys-kernel/rt-sources-2.6.33.7-r29

>>> Install rt-sources-2.6.33.7-r29 into /var/tmp/portage/sys-kernel/rt-sources-2.6.33.7-r29/image/ category sys-kernel
>>> Copying sources ...
>>> Completed installing rt-sources-2.6.33.7-r29 into /var/tmp/portage/sys-kernel/rt-sources-2.6.33.7-r29/image/

Cheers,
Mark