On Tue, Feb 16, 2010 at 05:41:39PM +0900, KOSAKI Motohiro wrote: > > On Tue, Feb 16, 2010 at 04:03:29PM +0900, KOSAKI Motohiro wrote: > > > > Unusuable free space index is a measure of external fragmentation that > > > > takes the allocation size into account. For the most part, the huge page > > > > size will be the size of interest but not necessarily so it is exported > > > > on a per-order and per-zone basis via /proc/pagetypeinfo. > > > > > > Hmmm.. > > > /proc/pagetype have a machine unfriendly format. perhaps, some user have own ugly > > > /proc/pagetype parser. It have a little risk to break userland ABI. > > > > > > > It's very low risk. I doubt there are machine parsers of > > /proc/pagetypeinfo because there are very few machine-orientated actions > > that can be taken based on the information. It's more informational for > > a user if they were investigating fragmentation problems. > > > > > I have dumb question. Why can't we use another file? > > > > I could. What do you suggest? > > I agree it's low risk. but personally I hope fragmentation ABI keep very stable because > I expect some person makes userland compaction daemon. (read fragmentation index > from /proc and write /proc/compact_memory if necessary). > then, if possible, I hope fragmentation info have individual /proc file. > I'd be somewhat surprised if there was an active userland compaction daemon because I'd expect them to be depending on direct compaction. Userspace compaction is more likely to be an all-or-nothing affair and confined to NUMA nodes if they are being used as containers. If a compaction daemon was to exist, I'd have expected it to be in-kernel because the triggers from userspace are so coarse. Still, I can break out the indices into separate files to cover all the bases. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>