On Nov 3, 2015, at 1:10 AM, Christoph Lameter wrote: Dear Christoph,
> On Sun, 1 Nov 2015, Jungseok Lee wrote: > >> There is no room to adjust 'atom_size' now when a generic percpu area >> is used. It would be redundant to write down an architecture-specific >> setup_per_cpu_areas() in order to only change the 'atom_size'. Thus, >> this patch adds a new definition, PERCPU_ATOM_SIZE, which is PAGE_SIZE >> by default. The value could be updated if needed by architecture. > > What is atom_size? Why would you want a difference allocation size here? > The percpu area is virtually mapped regardless. So you will have > contiguous addresses even without atom_size. I think Catalin have already written down a perfect explanation. I'd like memory with an alignment greater than PAGE_SIZE. But, __per_cpu_offset[] is PAGE_SIZE aligned under a generic setup_per_cpu_areas(). That is, secondary cores cannot get that kind of space. Thanks for taking a look at this doubtable change! Best Regards Jungseok Lee -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/