Manjaro (Arch) Has Realtime Kernels

What other apps and distros do you use to round out your studio?

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paulmerchant
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Manjaro (Arch) Has Realtime Kernels

Postby paulmerchant » Mon Aug 29, 2016 10:15 pm

As of a few weeks ago, Manjaro has been providing official compiled realtime kernels for music production in their repos, and with quite a few hardware support options.

Manjaro already makes it easy to enjoy Arch's cutting-edge rolling releases. Now Manjaro is making it super easy to run an Arch-based distro with a realtime kernel. I hope this brings even more activity to Arch's AUR and to the official Arch repos around music production. I've been a happy Manjaro user for a few years and these realtime kernels make me even happier.

If you don't mind going out on your own a bit and not being on AVLinux or KXstudio, Arch (or derivatives) can be a good music distro. Manjaro and realtime kernels can make it a much, much easier music distro.

I love the work done on KXstudio and AVLinux, but after running a rolling release based on Arch for so long, it would be hard for me to look back and try another distro. Are there any other Manjaro musicians out there? Any other Arch users excited about Manjaro's realtime kernels? I wonder if realtime kernels will make anyone take a first or second look at Manjaro.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby gimmeapill » Tue Aug 30, 2016 9:56 am

Apart from pre-built binaries slightly more recent than those from the Archaudio repo, what is the benefit of Manjaro + RT kernel vs Arch + RT Kernel?

I see in the Linux-RT comments that Manjaro devs contribute their patches https://aur.archlinux.org/packages/linux-rt/, (which is nice).
Still, no particularly compelling reason to jump on the bandwagon for existing Arch users...

Too bad we still cannot reliably benchmark performance when it comes to pro audio.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby CrocoDuck » Tue Aug 30, 2016 3:42 pm

gimmeapill wrote:Apart from pre-built binaries slightly more recent than those from the Archaudio repo, what is the benefit of Manjaro + RT kernel vs Arch + RT Kernel?

I would imagine that the easy and quick installation can be a big pro for many, especially for those who would configure their Arch very close to a vanilla Manjaro. Not my piece of cake tho, I like getting my hands dirty with Arch :P

gimmeapill wrote:I see in the Linux-RT comments that Manjaro devs contribute their patches?

Oh that's neat!

gimmeapill wrote:Too bad we still cannot reliably benchmark performance when it comes to pro audio.

Indeed, trying to understand how system configuration and software relates to pro audio performance is hard. I have realized few weeks ago that my Arch box works better with the stock kernel than with the RT kernel from archaudio... My hard-core jack setups are much more xruns free on linux than on linux-rt... I wonder why, or how to understand why.

We looked already into this and we found some sets of tests that could be performed. However, I have realized that building kernels and testing them is too much work for me at the moment, especially for the fact that I feel I would need a dedicated workstation (don't really want to stress my only laptop with endless compilation and tests)... Also I feel like I have started too many personal projects... dang. Maybe I will find the time to see how current linux-rt versions work on Btrfs filesystems (although I will only be able to check that on a virtual machine). Manjaro could actually make easier to test kernels as they are compiled... but again I would have to transition my Arch to Manjaro, which is a thing I can't do. I wish I had a test pc...
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Re: Manjaro (Arch) Has Realtime Kernels

Postby sysrqer » Tue Aug 30, 2016 4:45 pm

That's good to hear, the downside of manjaro has always been the lack of kernels it supports rather than 100 versions of the same one.
I always found their stock one to be pretty good with BFQ and preempt enabled. I always seem to have problems when I've used the distro in the past, ranging from minor to major, eventually I switched because I don't have time to troubleshoot.

The other downside is that there is no meta package or list of packages for plugins and programs for audio, unless you know what you are looking for specifically in AUR it can be pot luck as to whether you find everything. That's why I like kxstudio repos, it makes it very easy to discover plugins you may not have come across otherwise.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby eric71 » Wed Aug 31, 2016 6:54 am

This ia very good news, which I missed because I had stopped using Manjaro due to lack of certain things I use (like carla-git in AUR wasn't working). It seems carla is compliling again, and with these new rt kerels it may be worth checking out Manjaro again :)

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Re: Manjaro (Arch) Has Realtime Kernels

Postby paulmerchant » Wed Aug 31, 2016 5:29 pm

gimmeapill wrote:Apart from pre-built binaries slightly more recent than those from the Archaudio repo, what is the benefit of Manjaro + RT kernel vs Arch + RT Kernel?


The pre-built binaries are a huge plus for me. It literally takes forever (about 7 hours) to do kernel compiles on one little machine that I use for audio. It's going to be a dream to keep up easily with rolling updates, or to quickly test different realtime kernels, without that compile time.

CrocoDuck wrote:I would imagine that the easy and quick installation can be a big pro for many, especially for those who would configure their Arch very close to a vanilla Manjaro. Not my piece of cake tho, I like getting my hands dirty with Arch :P


You hit it. I like the quick installation, and I stopped distro shopping when I realized that vanilla Manjaro is pretty close to what I want anyway. Manjaro can also be an Arch entry point for people who aren't quite ready to get their hands Arch dirty.

sysrqer wrote:I always seem to have problems when I've used the distro in the past, ranging from minor to major, eventually I switched because I don't have time to troubleshoot.


I don't have much time to troubleshoot, either, but that's why I've stayed with Manjaro instead of getting deeper into Arch. However, I do troubleshoot audio, and I periodically compile my own audio apps, a lot more than I would if I was running something like AVLinux. For me, the advantages -- like the rolling releases, the latest apps, the ease of customizing (the vanilla install is not too bloated for me), the Arch and Manjaro documentation, etc. -- are well worth it.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby gimmeapill » Fri Sep 02, 2016 8:15 am

The pre-built binaries are a huge plus for me. It literally takes forever (about 7 hours) to do kernel compiles on one little machine that I use for audio. It's going to be a dream to keep up easily with rolling updates, or to quickly test different realtime kernels, without that compile time.

7h build time...Now I understand your pain ;-)
So yeah, binaries are more than a luxury in that case.

One tip that may help if you ever have to build manually again: edit the configure section of the pkgbuild and add "make localmodconfig" to get a super slim kernel (~12MB instead of ~60MB). Will be built only the modules currently loaded on the current system (there are caveats though).
On my machine this reduces build time from about 1h to 20-25 mins.

Coming back to Linux-RT on Arch: it looks like there are some discussions to move it to Community. Should that ever happen, I would most probably not bother compiling anything either.

One thing that worries me with the binaries is the rollback capabilities in case of a performance degradation with the latest RT patch.
It happened several times over the last years that I had to downgrade the RT kernel, and I usually keep around the last known *good* builds - just in case.
Not sure what is the Manjaro policy in this regard, is there something like the Arch Linux Archive? https://wiki.archlinux.org/index.php/Arch_Linux_Archive.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby CrocoDuck » Fri Sep 02, 2016 10:11 am

paulmerchant wrote:[The pre-built binaries are a huge plus for me. It literally takes forever (about 7 hours) to do kernel compiles on one little machine that I use for audio. It's going to be a dream to keep up easily with rolling updates, or to quickly test different realtime kernels, without that compile time.


You can also edit /etc/makepkg.conf in order to have PKGBUILD packages built in parallel by default (if the package needs to be built not in parallel the PKGBUILD will override it). This should save you time. Have a look.
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Re: Manjaro (Arch) Has Realtime Kernels

Postby sysrqer » Fri Sep 02, 2016 11:55 am

I'm really surprised by the build times mentioned above, when I used to build my own it took me 10mins to compile on a core2duo 2ghz. This was with what I needed (and some things I probably didn't need due to not knowing their function) so localmodconfig would be even less. Unless you guys have even more of a toaster than me.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby gimmeapill » Fri Sep 02, 2016 12:17 pm

I remember the days when you could build a standard kernel in 10 mins (back somewhere around Linux 2.6.32) but I'm afraid they are long over...
Currently I'm building with "-j5" on a core I5 3317U from 2012 (http://ark.intel.com/products/65707/Intel-Core-i5-3317U-Processor-3M-Cache-up-to-2_60-GHz) with 4GB RAM and it does take ages.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby sysrqer » Fri Sep 02, 2016 12:45 pm

That's curious indeed, the last one I built was 4. something so wouldn't be that much different. I think I had a couple of things set up to optimise compilation because this was in gentoo but I can't think anything significant right now.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby gimmeapill » Fri Sep 02, 2016 12:53 pm

Could it be that you used sth like ccache?
I plan to run an update this evening. I'll try to pay closer attention to the time it takes and report back.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby sysrqer » Fri Sep 02, 2016 2:11 pm

Yes, I was using ccache. That certainly helped with portage compilations but I don't remember if I had it set up for things outside portage. I think I had it set to build in tmpfs as well, which may have been the factor that made a difference.

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Re: Manjaro (Arch) Has Realtime Kernels

Postby paulmerchant » Sat Sep 03, 2016 2:39 am

On my decent computer, I haven't needed a realtime kernel. I've had good performance with Manjaro stock kernels (preempt).

On my cheapo AMD A4 dual-core, basically a netbook, I can't come close to doing what I want without a realtime kernel. I get a ton of xruns on stock (although decent performance with realtime). It's also so slow that it was the one taking over 7 hours to compile the realtime kernel. I guess that I could have optimized the kernel compile times, but now with pre-compiled realtime kernels I don't have to. :D

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Re: Manjaro (Arch) Has Realtime Kernels

Postby CrocoDuck » Sat Sep 17, 2016 2:14 pm

Speaking of compiled stuff, this repo recently surfaced. Didn't really tested it at the moment. Guess it is also best to figure out whether it can be trusted. If so, it is for sure nice to have compiled versions of AUR stuff.
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