On Thu, Jan 6, 2011 at 9:09 AM, Jack Steiner <steiner@xxxxxxx> wrote: > SGI is currently developing an x86_64 system with more than 16TB of memory per > SSI. As far as I can tell, this should be supported. The relevant definitions > such as MAX_PHYSMEM_BITS appear ok. > > One area of concern is page counts. Exceeding 16TB will also exceed MAX_INT > page frames. The kernel (at least in all places I've found) keep pagecounts > in longs. > > Have I missed anything? Should this > 16TB work? Are there any kernel problems or > problems with user tools that anyone knows of. > > Any help or pointers to potential problem areas would be appreciated... I don't know of any place that uses ints to count physical pages. However, the page_referenced functions in mm/rmap.c return reference counts as an integer. I believe a wraparound would only mislead the LRU algorithms, but I haven't thought about it much. (Not sure why we return a count anyway, since I believe callers only want to compare it against zero ???) -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>