On Thu, 2018-03-01 at 16:19 -0700, Logan Gunthorpe wrote: (Switching back to my non-IBM address ...) > On 01/03/18 04:00 PM, Benjamin Herrenschmidt wrote: > > We use only 52 in practice but yes. > > > > > That's 64PB. If you use need > > > a sparse vmemmap for the entire space it will take 16TB which leaves you > > > with 63.98PB of address space left. (Similar calculations for other > > > numbers of address bits.) > > > > We only have 52 bits of virtual space for the kernel with the radix > > MMU. > > Ok, assuming you only have 52 bits of physical address space: the sparse > vmemmap takes 1TB and you're left with 3.9PB of address space for other > things. So, again, why doesn't that work? Is my math wrong The big problem is not the vmemmap, it's the linear mapping. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
