Re: [RFC v13][PATCH 00/14] Kernel based checkpoint/restart

[Andrew Morton]

On Sun, 15 Feb 2009 00:08:02 +0100 Ingo Molnar <mingo@xxxxxxx> wrote:

> 
> * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> > Similar to the way in which perfectly correct and normal kernel
> > sometimes has to be changed because it unexpectedly upsets the -rt
> > patch.
> 
> Actually, regarding -rt, we try to keep that in two buckets:
> 
>  1) Normal kernel code works but is unclean or structured less
>     than ideal. In this case we restructure the mainline code,
>     but that change stands on its own four legs, without any
>     -rt considerations.
> 
>  2) Normal kernel code that is clean - i.e. a change that only
>     matters to -rt. In this case we dont touch the mainline code,
>     nor do we bother mainline.
> 
> Do you know any specific example that falls outside of those categories?
> 

It happens fairly regularly.  Problems with irqs-off regions, problems
with preempt_disable() regions (came up just yesterday with a patch from
Jeremy).

Plus some convert-to-sleeping-lock conversions over the years which
weren't obviously needed in mainline.  Or which at least had -rt
motivations.  But that's different.





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