From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.dumazet@gmail.com (Eric Dumazet) Date: Sat, 31 Mar 2012 23:00:08 +0200 Subject: [PATCH RFC] Simplify the Linux kernel by reducing its state space In-Reply-To: <20120331163321.GA15809@linux.vnet.ibm.com> References: <20120331163321.GA15809@linux.vnet.ibm.com> Message-ID: <1333227608.2325.4054.camel@edumazet-glaptop> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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.