[PD] [OT] linux preempt kernel vs rt kernel

[András Murányi]

The point is that the newest kernel versions are not available in rt flavour
(the latest is 2.6.31-11 and my experiences were not good with it). This is
first time i heard about the lowlatency flavour, but it's not in my Ubuntu
repos.
So i'm afraid, if i want a new rt kernel (for 64-bit...), i'll have to use a
ppa or build my own.

Andras

2010/6/30 Pedro Lopes <pedro.lopes at ist.utl.pt>

> What?
>
> Of course not. Its a pacth - no compiling needed. But be sure to keep a
> generic kernel at the boot (just use grub to preserve a boot without rt, I
> never had problems and use the same rt kernel for 1 year, but safety first
> =P)
> Real time (-rt) and Low latency (-lowlatency) kernels
>
> You may want to install the -lowlatency kernel, you can simply do:
>
>  sudo apt-get install linux-lowlatency linux-headers-lowlatency
>
> If you still experience Xruns or you have a firewire sound card supported
> by the FFADO project, you may want to install the -rt kernel:
>
>  sudo apt-get install linux-rt linux-headers-rt
>
>
>
> 2010/6/30 András Murányi <muranyia at gmail.com>
>
> Buh, it seems then i'll need to get a kernel from a PPA or compile it
>> myself. A bit afraid of it, honestly.
>> Thanks for the explanation!
>>
>> Andras
>>
>>
>> On Sat, Jun 26, 2010 at 12:50 PM, Ricardo Lameiro <
>> ricardolameiro at gmail.com> wrote:
>>
>>> well, AFAIK, the "RT" Kernel is a generic kernel that is modified by a
>>> special patch, that is made by Ingo Molnár. This patch gives the kernel the
>>> ability to have a behavior that allows the assignment of time frames and
>>> allocations to compute "rt" flagged tasks. Maybe this could be translated to
>>> the scheduler.In the other hand, the preemptive kernel, its a normal Generic
>>> kernel, that its compiled with different options. At compile time, the
>>> configuration of the scheduler and company are configured more aggressively
>>> to give a better response to the "rt" flagged apps.
>>>
>>> As my opinion, that is worth nothing...., the preemptive kernels are
>>> comming into a very good level, since the main tree ot the generic kernel,
>>> has absorbing parts of Ingo's patches. But, still, the RT kernel is way more
>>> accurate on the scheduling etc. problem is that, RT kernels are in nature
>>> more Power hungry, and by the nature of its working, they could hang easily
>>> a computer, keeping only processing an high prio task.
>>>
>>> If I said something wrong, please correct me, I have looked at this stuff
>>> since a year to try to understand it better, so if someone can explain it
>>> better, please do.
>>>
>>> Ricardo Lameiro
>>>
>>>
>>>
>>> 2010/6/26 Andre "Osku" Schmidt <andre.osku.schmidt at osku.de>
>>>
>>> On Fri, 2010-06-25 at 22:17 +0200, András Murányi wrote:
>>>> > Hello people,
>>>> >
>>>> > does anyone know what is the real difference between an 'rt' and a
>>>> > 'preempt' kernel in linux?
>>>>
>>>> dunno, but here's a pretty interesting talk about real-time kernel
>>>>
>>>> http://lac.linuxaudio.org/2010/recordings/day2_1045_How_the_Real_Time_Kernel_Helps_Audio_and_Video_Applications.ogv
>>>>
>>>>
>>>>
>>>>
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