Re: [LAU] 200 lines kernel patch

Ray Rashif wrote:
> On 21 November 2010 02:33, torbenh <torbenh@email-addr-hidden> wrote:
>> On Sat, Nov 20, 2010 at 08:26:45AM -0500, Paul Davis wrote:
>>> On Sat, Nov 20, 2010 at 4:48 AM, Atte André Jensen <atte@email-addr-hidden> wrote:
>>>> Hi
>>>>
>>>> Aparently a new, 200 lines kernel patch have been buzzing the web lately,
>>>> supposedly it should provide a much more responsive desktop.
>>>>
>>>> But this userspace alternative should be even better:
>>>> http://www.webupd8.org/2010/11/alternative-to-200-lines-kernel-patch.html
>>>>
>>>> Anyone heard of it, tried it and/or has any thoughts whether it has anything
>>>> to offer on a DAW?
>>> it doesn't look terribly relevant because a DAW is going to schedule
>>> most threads that matter with SCHED_FIFO. these threads will be
>>> scheduled by a different set of rules than SCHED_OTHER (i.e. most of
>>> the desktop threads, and the scheduling class that is affected by the
>>> patch). that's not to say it might not still make things feel a bit
>>> better, but it won't really make lower latencies possible etc. etc.. I
>>> think.
>> looking at the 200lines patch... it seems to activate RT_GROUP_SCHED
>> if anybody know how the system needs to be configured, so that jackd
>> runs with this option on, it might be nice if you told us.
>>
>> if we really get kernels with this turned on soon, we better be prepared.
>
> In fact, isn't cgroups incompatible with realtime scheduling? Not
> quite sure where I'm quoting that from but I vaguely recall something
> like that.

According to extended discussion of this on Slashdot yesterday, the
kernel patch and the alternative listed are essentially the same: the
alternative is what they were using in testing to decide what to put
into the kernel patch. Kernel developers decided that the patch was the
better way to do it. It uses a feature that's been in the kernel for a
couple of years now.

No info about impact on RT scheduling that I saw mentioned anywhere in
the discussion.

-- 
David
gnome@email-addr-hidden
authenticity, honesty, community
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