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AV Linux 2018... what kernel do ya want for default??

Posted: Mon Dec 18, 2017 7:20 pm
by GMaq
Hi,

I don't know how many AVL users there are here anymore but I am copying this post from my forum to get some feedback since we have a large and experienced Linux Audio community here....

It has been a difficult year personally which has limited my time for AVL and the forum somewhat but I have been actively working on AV Linux 2018 which I hope to release early next year, this 2018 release will sit on top of the now completed Debian Stretch 9 (AV Linux 2017.4.9 was still based on Debian Stretch as Testing). This next release will fix some of the minor bugs in 2017.4.9 and bring a lot of updates and new additions and plugins. I also have some new convenience features as well as much work to do on further expanding and improving the User Manual..

Before this release I have a question for the community...

The newer AVL releases (2016 and up) have come with a default RT kernel to give the very best potential for performance, this has had a mixed blessing of providing a fast low latency system but unfortunately the RT kernel patch is incompatible with the 3rd party proprietary nVidia Video card drivers and necessitates the use of the Open Source 'Nouveau' nVidia driver. It has been shown that Nouveau is not threaded in a way that works well for Audio work with numerous plugin windows open, I have suspicions it also doesn't play nicely with some Video Editors like Kdenlive and Cinelerra...

So for users of AMD and Intel Video chipsets AV Linux works well with the default RT kernel... for nVidia users there are a lot of problems and extremely variable results with the huge number of different nVidia cards out there. At the end of the day speed without reliability is a HUGE deficit for an A/V workstation... :oops:

So....


We now have BOTH 'lowlatency' Kernels in the AV Linux kernel repository that ARE compatible with NVidia's proprietary drivers and as always we have our fast n' furious 'RT' kernels..

For the next AVL release is it better to ship the fastest RT option by default with documentation to explain how to move to a 'lowlatency' kernel and install the proprietary nVidia drivers with the included sgfxi script??

OR...


Is it better to ship with a 'lowlatency' default kernel with documentation to explain how to install an RT kernel if you want faster, lower latency Audio performance??

Please share your thoughts...
;)

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 3:12 am
by GuntherT
My vote would be to ship the RT Kernal by default and provide instructions and the low latency kernel for the NVIDIA users who need it. Maintain the focus on performance. Few distributions ship with a RT kernel by default; it is one your project's standout characteristics in my opinion.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 9:03 am
by chaocrator
GMaq wrote:We now have BOTH 'lowlatency' Kernels in the AV Linux kernel repository that ARE compatible with NVidia's proprietary drivers and as always we have our fast n' furious 'RT' kernels..
the best option IMO is shippng with both, but booting lowlatency as a safer option by default.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 9:36 am
by Jack Winter
Installing both and defaulting to booting lowlatency might be the best option.

On the other hand, afaik it's possible to run nvidia with a rt kernel. The kernel needs a patch, and the nvidia kernel module building needs an additional option to not abort when it detects the rt kernel. I do have it working on archlinux, so I don't see why it shouldn't work for av linux..

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 3:34 pm
by GMaq
Jack Winter wrote:Installing both and defaulting to booting lowlatency might be the best option.

On the other hand, afaik it's possible to run nvidia with a rt kernel. The kernel needs a patch, and the nvidia kernel module building needs an additional option to not abort when it detects the rt kernel. I do have it working on archlinux, so I don't see why it shouldn't work for av linux..
Hi Jack!

Yes it possible, however as we've discussed elsewhere nVidia likes to change their game pretty frequently and they do go out of their way to make their driver NOT work OOTB with RT so as someone who is already spread too thin I'm not interested in following nVidia through the funhouse. For single Linux power users on their own systems that want to keep a steady kernel and Video driver well sure that's a very different thing...

Secondly is the fact that for a very high percentage of people with agreeable hardware a lowlatency kernel is quite sufficient, a great example is the large number of KXStudio users here who don't even have an option for an RT in Ubuntu (unless they install one of our AVL RT's) and I rarely hear complaints about the latency performance of KXStudio.

So to summarize AVL users with nVidia are a subset of the total user base and a large percentage of them will be quite happy with the performance of a lowlatency kernel and the nVidia proprietary driver... for the relatively tiny edge case of people that are left that feel they have to have nVidia+RT they can either (a) dive in to patching and hacking to get it to work or (b) Use Nouveau+RT...(I do with no problems on my older nVidia card) or (c) Use another Distro like Arch that has nice people like you who make it work.. :D

There is no way to please everybody, I learned that long ago... for me the 'benefit math' doesn't work to expend the extra effort. :wink:

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 3:42 pm
by GMaq
chaocrator wrote:
GMaq wrote:We now have BOTH 'lowlatency' Kernels in the AV Linux kernel repository that ARE compatible with NVidia's proprietary drivers and as always we have our fast n' furious 'RT' kernels..
the best option IMO is shippng with both, but booting lowlatency as a safer option by default.
Hi,

I do like this suggestion, however a whole extra kernel+headers adds a lot of mass (200Mb) to an already large ISO... It's worth testing though :wink:

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 3:46 pm
by Jack Winter
Still I insist ;) AFAIK there is just one patch needed when building the kernel, and the use of IGNORE_PREEMPT_RT_PRESENCE=1 when building the nvidia kernel modules, that's really all there is to it.. Have experienced a lot of thornier problems than this one packaging software ;)

Of course I can't guarantee what nvidia won't break it some other way, and I know that it's a pain in the @ss to build and package the modules as I've done it myself for years.

Up to you what you chose to do, but I still have to second the above opinion that having a rt kernel is probably one of avlinux' strong points...

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Tue Dec 19, 2017 4:45 pm
by sysrqer
I don't use AVL and probably won't in the foreseeable future but I'd personally be happy with low latency. I've only seen a negligible difference with the RT kernel, although I don't record much. Not having future problems with nvidia would be more of a benefit than the gains I experienced with the RT.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Fri Dec 22, 2017 8:39 pm
by gennargiu
Hi, insert in new version avl 2018 uefi support :wink:

gennaro

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Sat Dec 23, 2017 8:06 am
by chaocrator
GMaq wrote:
chaocrator wrote:the best option IMO is shippng with both, but booting lowlatency as a safer option by default.
I do like this suggestion, however a whole extra kernel+headers adds a lot of mass (200Mb) to an already large ISO... It's worth testing though :wink:
still under 4.4 GiB or even 3.8 GiB, so will fit DVD5 and 4GB flash drives either )
i live on lubuntu with AV kernels for 2 years, and lowlatency for daily desktop use + RT for live/rehearsals is just perfect combo.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Sun Dec 24, 2017 8:20 am
by tramp
I using exclusively rt-kernels with the nouveau driver (GeForce GT 220) for all my tasks.
Currently I run kernel 4.14.3-rt5, before that one I run 4.4.7-rt6.
The versions between 4.4 and 4.14 give me some stability issues, mostly early boot segfaults, but the current 4.14-rt run flawless on my machine.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Sun Dec 24, 2017 4:50 pm
by magicalex
Sorry to hear you've had a tough year.

I'd go with the low-latency. I suspect few people will notice a performance difference and you'll be making life a lot easier for nvidia folk.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Mon Dec 25, 2017 8:40 am
by thetotalchaos
Hi Glen,

I see it this way. What we choose to use is what has value to us. Its what will prevail in the future.

Looking at it that way, the choice should be Linux-RT. Because at the end it is more important in the bigger picture, than proprietary video drivers. We must encourage what has value to us, as individuals and as a community. Another way too look at it, is that not promoting the proprietary Nvidia drivers, we are giving a chance at Nouveau open-source drivers.

And at the end although we value the Linux-RT kernel and its place in our ProAudio experience, there are lack of distributions that provide it by default.

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Mon Dec 25, 2017 9:28 am
by Jack Winter
I'll repeat 8)

Linux-rt can most certainly be used with nvidia.. One patch for the kernel, and an additional parameter to override the check that makes the nvidia module building process abort. Easiest is to use dkms to build nvidia and to do the following: "sed -i 's/NV_EXCLUDE_BUILD_MODULES/IGNORE_PREEMPT_RT_PRESENCE=1 NV_EXCLUDE_BUILD_MODULES/' dkms.conf", or without dkms just add "IGNORE_PREEMPT_RT_PRESENCE=1" to the make command that builds the nvidia modules.

Personally I've used nvidia on rt for many years now. I do normally use the builtin Intel GPU and just use nvidia with bumblebee. Both for testing and for the occasional game as for various reasons I vastly prefer Intel for day to day use, especially for low latency audio use.

And yes I'd agree with the sentiment that please provide linux-rt as it does have a slight edge, and is one of AV's distinct advantages to many other distros!

Re: AV Linux 2018... what kernel do ya want for default??

Posted: Mon Dec 25, 2017 10:58 am
by sysrqer
thetotalchaos for nvidia users its not a case of preferring to use one or the other, nouveau has serious problems when it comes to realtime audio - segfaults, lockups and kernel flooding error messages. I don't know if all users experience this but I certainly did and it's not good losing work randomly.