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

Subject: Re: [PATCH RFC] Simplify the Linux kernel by reducing its state space
From: Eric Dumazet <>
Date: Sat, 31 Mar 2012 23:00:08 +0200
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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 <>
> Reviewed-by: Thomas Gleixner <>
> ---

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.

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