Re: Patch "sched: Give CPU bound RT tasks preference" has been added to the 2.6.32-longterm tree

[Mike Galbraith <efault@gmx.de>]

On Wed, 2011-02-16 at 09:55 +0100, Jiri Slaby wrote:
> On 02/16/2011 09:25 AM, Ingo Molnar wrote:
> > 
> > * Mike Galbraith <efault@gmx.de> wrote:
> > 
> >> On Tue, 2011-02-15 at 18:02 -0500, Steven Rostedt wrote:
> >>> [ Added LKML ]
> >>>
> >>> On Tue, 2011-02-15 at 13:17 -0800, gregkh@suse.de wrote:
> >>>> This is a note to let you know that I've just added the patch titled
> >>>>
> >>>>     sched: Give CPU bound RT tasks preference
> >>>>
> >>>> to the 2.6.32-longterm tree which can be found at:
> >>>>     http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
> >>>>
> >>>> The filename of the patch is:
> >>>>      0006-sched-Give-CPU-bound-RT-tasks-preference.patch
> >>>> and it can be found in the queue-2.6.32 subdirectory.
> >>>>
> >>>> If you, or anyone else, feels it should not be added to the 2.6.32 longterm tree,
> >>>> please let <stable@kernel.org> know about it.
> >>>>
> >>>>
> >>>
> >>> I don't mind this patch being added to the long term tree. But I'm
> >>> curious about what is the criteria for adding changes to it? This is a
> >>> performance improvement and not a critical bug fix.
> >>
> >> Yes, I added it for the performance.  .32-stable is enterprise beans and
> >> biscuits.  Same reason I added the load balancing fixes, boxen won't
> >> explode without them, but load balancing performs better with them.
> > 
> > We try to concentrate on regression fixes though.
> 
> Hi, I cannot fully agree with this. The question is who are "we" here?
> If every packager using this stable tree is forced by users/customers to
> take it anyway, it's better to have it in stable.
> 
> It has several reasons:
> * It will have an eye of experts on them. Not that at distro providers
> there are no experts, but the authors who are cced here know definitely
> the code better.
> * Not every packager has to duplicate others work.
> * The stable tree changes constantly. Managing hundreds of patches
> applied to a stable tree before kernels are being packaged is thus
> sometimes a hell. Reducing this number is a good thing(TM).

Fully agree on all fronts, but it's a hard call.  When I start auditing,
I sweat bullets.  I see piles of bug fixes, and piles of performance
enhancements, all of which are ever so tempting, all of which are worthy
of backport.. but humans _are_ buggy, so there is risk involved.

	-Mike