On Thu, 16 Nov 2006, Linus Torvalds wrote: > > > On Thu, 16 Nov 2006, Alan Stern wrote: > > On Thu, 16 Nov 2006, Linus Torvalds wrote: > > > > > > Paul, it would be _really_ nice to have some way to just initialize > > > that SRCU thing statically. This kind of crud is just crazy. > > > > I looked into this back when SRCU was first added. It's essentially > > impossible to do it, because the per-cpu memory allocation & usage APIs > > are completely different for the static and the dynamic cases. > > I don't think that's how you'd want to do it. > > There's no way to do an initialization of a percpu allocation statically. > That's pretty obvious.
Hmmm... What about DEFINE_PER_CPU in include/asm-generic/percpu.h combined with setup_per_cpu_areas() in init/main.c? So long as you want all the CPUs to start with the same initial values, it should work. > What I'd suggest instead, is to make the allocation dynamic, and make it > inside the srcu functions (kind of like I did now, but I did it at a > higher level). > > Doing it at the high level was trivial right now, but we may well end up > hitting this problem again if people start using SRCU more. Right now I > suspect the cpufreq notifier is the only thing that uses SRCU, and it > already showed this problem with SRCU initializers. > > So I was more thinking about moving my "one special case high level hack" > down lower, down to the SRCU level, so that we'll never see _more_ of > those horrible hacks. We'll still have the hacky thing, but at least it > will be limited to a single place - the SRCU code itself. Another possible approach (but equally disgusting) is to use this static allocation approach, and have the SRCU structure include both a static and a dynamic percpu pointer together with a flag indicating which should be used. Alan Stern - 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/
