On Fri, 2 Apr 2010 17:02:40 +0100 Mel Gorman <mel@xxxxxxxxx> wrote: > Fragmentation index is a value that makes sense when an allocation of a > given size would fail. The index indicates whether an allocation failure is > due to a lack of memory (values towards 0) or due to external fragmentation > (value towards 1). 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/extfrag_index (/proc/sys/vm?) Like unusable_index, this seems awfully specialised. Perhaps we could hide it under CONFIG_MEL, or even put it in debugfs with the intention of removing it in 6 or 12 months time. Either way, it's hard to justify permanently adding this stuff to every kernel in the world? I have a suspicion that all the info in unusable_index and extfrag_index could be computed from userspace using /proc/kpageflags (and perhaps a bit of dmesg-diddling to find the zones). If that can't be done today, I bet it'd be pretty easy to arrange for it. -- 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>