[elrepo] Realtime kernel for audio/games?

[Alan Bartlett]

On 13 October 2014 12:38, Ljubomir Ljubojevic <centos at plnet.rs> wrote:
> On 10/13/2014 01:23 PM, Ljubomir Ljubojevic wrote:
>> On 10/13/2014 01:19 PM, Ljubomir Ljubojevic wrote:
>>> Hi guys.
>>>
>>> Is there any desire, or even need to create a realtime kernel aimed at
>>> audio/games?
>>>
>>> Since Desktop/gaming system and servers have different priorities, I was
>>> wondering how things are with current CentOS kernels. For CentOS 5 there
>>> were CCRMA kernels.
>>>
>>> Non-Gaming purpose would be for audio conversion/streaming.
>>>
>>
>> Understanding low latency
>>
>> Summary
>>
>> Summarizing, you need tuned drivers that do not disable interrupts for
>> long, low latency patches in the kernel so that the scheduler runs often
>> enough and your application itself has to run with the SCHED_FIFO
>> scheduling policy so that it gets the best chance of grabbing the
>> processor when it needs it.
>>
>> When everything is in place things work incredibly well. The system can
>> be running an audio task with no dropouts and a few milliseconds of
>> latency while the computer is being loaded with disk accesses, screen
>> refreshes and whatnot. The mouse gets jerky, windows update very slowly
>> but not a dropout to be heard.
>>
>> I wonder if anybody got this far :-)
>> http://ccrma.stanford.edu/planetccrma/software/understandlowlat.html
>>
>
> I apologize for not doing some research later, I went back to CCRMA and
> found out that there is repositories for Fedora 19, so patching
> your/stock kernels should be fairly straightforward.
>
> http://ccrma.stanford.edu/planetccrma/software/installplanettwenty.html
>
> http://ccrma.stanford.edu/planetccrma/mirror/fedora/linux/planetccrma/19/SRPMS/
>
> I will contact the maintainer if he would create a branch for CentOS 7
> and report back.
>
> --
> Ljubomir Ljubojevic

Thank you. That would be the most sensible path to follow.

We would always encourage end-users with a need that is not satisfied
by the basic kernel packages that we ship to investigate a "local"
solution. Currently the build & provide of a kernel-lt package set for
EL5, a kernel-lt & kernel-ml package set for EL6 and a kernel-ml
package set for EL7 takes a significant amount of time. The logic
behind our provision of the above is quite simple -- to allow end
users to be able to make use of hardware which is currently
unsupported by the distribution kernels and is also unsupported by
means of a specific kmod package.

Specialised builds of a kernel (say, for example, Xen or RT) are
something that we will not be providing. However we will always try to
assist an end user to understand our current build process and thus to
be able to become "self-sufficient" in maintaining a "local" build of
such specialist kernels.

Alan.