On Sun, Apr 01, 2012 at 12:19:25AM +0200, Lorenz Kolb wrote: > 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. Perhaps a branch on a public git tree? If you are doing what I suspect you are, you will end up with a very large patch set. ;-) Thanx, Paul > 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 > > > >_______________________________________________ > >Linuxppc-dev mailing list > >Linuxppc-dev@xxxxxxxxxxxxxxxx > >https://lists.ozlabs.org/listinfo/linuxppc-dev >
