On 01/13/2015 12:41 PM, Kirill A. Shutemov wrote: > On Tue, Jan 13, 2015 at 12:36:23PM -0800, Dave Hansen wrote: >> On 01/13/2015 11:14 AM, Kirill A. Shutemov wrote: >>> pgd_t * pgd; >>> atomic_t mm_users; /* How many users with user space? */ >>> atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */ >>> - atomic_long_t nr_ptes; /* Page table pages */ >>> + atomic_long_t nr_pgtables; /* Page table pages */ >>> int map_count; /* number of VMAs */ >> >> One more crazy idea... >> >> There are 2^9 possible pud pages, 2^18 pmd pages and 2^27 pte pages. >> That's only 54 bits (technically minus one bit each because the upper >> half of the address space is for the kernel). > > Does this math make sense for all architecures? IA64? Power? No, the sizes will be different on the other architectures. But, 4k pages with 64-bit ptes is as bad as it gets, I think. Larger page sizes mean fewer page tables on powerpc. So the values should at least _fit_ in a long. Maybe it's not even worth the trouble. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>