* Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> wrote: > Alan D. Brunelle wrote: > > > I think you're right: the kernel as a whole may not be ready for 4,096 > > CPUs apparently... > > Mike has been working diligently on getting all these cpumasks off the > stack for the last months and has created an infrastructure to do > this. So I think we are close. It might just be a matter of merging > some more patches that are still left in Ingo's tree. hm, there are no such patches left that i know of - the only bits in -tip are the zero-based percpu, which was found to be a bit fragile in testing: earth4:~/tip> git-log-line --author=Travis linus.. d379497: Zero based percpu: infrastructure to rebase the per cpu area to zero b3a0cb4: x86: extend percpu ops to 64 bit [and it has no relevance to stack footprint.] So i dont think the current cpumask_t approach will work. We simply should not get into an endless fight against the windmills that introduce on-stack cpumask_t again and again. We should just take the plunge once and do a clean alloc/free cpumask model. Most of the hotpath cpumasks are constant or pre-constructed, so they are not a real issue. Plus, on the general question of stack footprint problems and the difficulty of debugging them, the worst-case stack footprint tracer i wrote for -rt some time ago should be dusted off as well and put into ftrace. David has something quite close to that for Sparc64 already. Ingo -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
