Hello Dave, On Mon, Jun 02, 2014 at 09:11:37AM -0700, Dave Hansen wrote: > On 06/01/2014 10:24 PM, Naoya Horiguchi wrote: > > Detail about the data format being passed to userspace are explained in > > inline comment, but generally in long entry format, we can choose which > > information is extraced flexibly, so you don't have to waste memory by > > extracting unnecessary information. And with FINCORE_SKIP_HOLE flag, > > we can skip hole pages (not on memory,) which makes us avoid a flood of > > meaningless zero entries when calling on extremely large (but only few > > pages of it are loaded on memory) file. > > Something similar could be useful for hugetlbfs too. For a 1GB page, > it's pretty silly to do 2^18 entries which essentially repeat the same > data in an interface like this. Good point. For hugetlbfs file, we link a hugepage to pagecache at the index of "hugepage" offset, so the second 1GB page in a hugetlbfs file are linked to index 1, not 2^18. Current version of fincore() already handle hugepage properly, so meaningless data copy doesn't happen. Thanks, Naoya Horiguchi -- 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>