> > Why do you want to create a virtual page table at the PMD level ? Also, > > you are changing the geometry of the page tables which I think we don't > > want. We chose that geometry so that the levels match the segment sizes > > on server, I think it may have an impact with the hugetlbfs code (check > > with David), it also was meant as a way to implement shared page tables > > on hash64 tho we never published that. > > The number of virtual page table misses were very high on certain loads. > Cutting back to a virtual PMD eliminates most of that for the benchmark I > tested, though it could still be painful for access patterns that are > extremely spread out through the 64-bit address space. I'll try a full > 4-level walk and see what the performance is like; I was aiming for a > compromise between random access and linear/localized access.
Let's get more numbers first then :-) > Why does it need to match segment sizes on server? I'm not sure whether we have a dependency with hugetlbfs there, I need to check (remember we have one page size per segment there). For sharing page tables that came from us using the PMD pointer as a base to calculate the VSIDs. But I don't think we have plans to revive those patches in the immediate future. Cheers, Ben. > As for hugetlbfs, it merged easily enough with Becky's patches (you'll have > to ask her when they'll be published). > > -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
