On Tue, Feb 19, 2008 at 10:32:38AM -0800, Mike Travis wrote: > Andi Kleen wrote: > > On Tue, Feb 19, 2008 at 07:48:54AM -0800, Mike Travis wrote: > >> Andi Kleen wrote: > >>> Yinghai Lu <[EMAIL PROTECTED]> writes: > >>> > >>>> we don't need copy too. already have x86_cpu_to_node_map > >>> That's a regression (probably from Mike's patches?). Until recently it > >>> was > >>> used. > >> Yes, I had removed it because I couldn't find any references to it. > > > > Hmm, maybe it regressed earlier. Sorry if I blamed you incorrectly. > > Anyways at some point this definitely worked. I remember writing > > the code ;-) > > > >> And reading one's own percpu variables should be as efficient as > >> reading one's own pda. > > > > Sure, but the point is that getting the current node is a common > > operation, so it should be a single reference and not go through a > > lookup table. > > > > How it is actually implemented -- through PDA or through you new > > equivalent per cpu variables -- does not really matter as long > > as the resulting code is only a single instruction. Using > > the lookup array from the cpu number is wrong. > > > > My patch just fixed it back to use the PDA in the old style for now, > > but if all your per cpu stuff is merged (I admit I haven't tracked > > if it is or not) replacing that with a per cpu variable would work too > > if it then generates the same code as with PDA. > > > > -Andi > > I'll look at it some more as I don't really have a preference either. > One thing that also bothered me was other cpus read the per cpu > variable to get the node number whilst the current cpu reads the pda > variable. I'll see about resolving that quirky-ness. (All one or all > the other.)
This information should always come from the same variable. > (And of course the problem with cpus on nodes with no local memory > needs to be resolved as well.) All CPUs get assigned to some node at boot. And there should be always per cpu variables or pda to use. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
