Re: [PATCH RFC] Simplify the Linux kernel by reducing its state space

[Lorenz Kolb]

With that patchset in mind, I am working on a really huge patch, which 
will greatly simplify the Linux kernel  for the real problem of having 
that number of CPUs.

That patch will have a lot of changes all over the architectures, so 
what will be the best way to post it? Should I split it architecture 
dependend and into one generic part.

Currently it is a large blob of millions of changes, but will greatly 
simplify the Linux kernel.

Regards,

Lorenz Kolb

Am 31.03.2012 23:21, schrieb Paul E. McKenney:
> On Sat, Mar 31, 2012 at 11:00:08PM +0200, Eric Dumazet wrote:
>    
> > On Sun, 2012-04-01 at 00:33 +0800, Paul E. McKenney wrote:
> >      
> > > Although there have been numerous complaints about the complexity of
> > > parallel programming (especially over the past 5-10 years), the plain
> > > truth is that the incremental complexity of parallel programming over
> > > that of sequential programming is not as large as is commonly believed.
> > > Despite that you might have heard, the mind-numbing complexity of modern
> > > computer systems is not due so much to there being multiple CPUs, but
> > > rather to there being any CPUs at all.  In short, for the ultimate in
> > > computer-system simplicity, the optimal choice is NR_CPUS=0.
> > >
> > > This commit therefore limits kernel builds to zero CPUs.  This change
> > > has the beneficial side effect of rendering all kernel bugs harmless.
> > > Furthermore, this commit enables additional beneficial changes, for
> > > example, the removal of those parts of the kernel that are not needed
> > > when there are zero CPUs.
> > >
> > > Signed-off-by: Paul E. McKenney<paulmck@xxxxxxxxxxxxxxxxxx>
> > > Reviewed-by: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
> > > ---
> > >        
> > Hmm... I believe you could go one step forward and allow negative values
> > as well. Antimatter was proven to exist after all.
> >
> > Hint : nr_cpu_ids is an "int", not an "unsigned int"
> >
> > Bonus: Existing bugs become "must have" features.
> >      
> ;-) ;-) ;-)
>
>    
> > Of course there is no hurry and this can wait 365 days.
> >      
> James Bottomley suggested imaginary numbers of CPUs some time back,
> and I suppose there is no reason you cannot have fractional numbers of
> CPUs, and perhaps irrational numbers as well.  Of course, these last two
> would require use of floating-point arithmetic (or something similar)
> in the kernel.  So I guess we have at several years worth.  Over to you
> for the negative numbers.  ;-)
>
> 							Thanx, Paul
>
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>    

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