On Tue, Feb 15, 2011 at 09:05:25AM -0800, Dave Hansen wrote: > On Tue, 2011-02-15 at 18:01 +0100, Andrea Arcangeli wrote: > > > The entire mapping is contained in a THP but the > > > KernelPageSize shows 4kb. For cases where the mapping might > > > have mixed page sizes this may be okay, but for this > > > particular mapping the 4kb page size is wrong. > > > > I'm not sure this is a bug, if the mapping grows it may become 4096k > > but the new pages may be 4k. There's no such thing as a > > vma_mmu_pagesize in terms of hugepages because we support graceful > > fallback and collapse/split on the fly without altering the vma. So I > > think 4k is correct here > > How about we bump MMUPageSize for mappings that are _entirely_ huge > pages, but leave it at 4k for mixed mappings? Anyone needing more > detail than that can use the new AnonHugePages count. Anyone needing the detail that you ask for, already can use the AnonHugePages count. > KernelPageSize is pretty ambiguous, and we could certainly make the > argument that the kernel is or can still deal with things in 4k blocks. That's my point. We could bring it to 2m whenever AnonHugePages==Anonymous, that's a two liner change, but I'm not really sure if it makes sense or it provides any meaningful info. That is a slot specific to show hugetlbfs presence and to differentiate between 2m/1g mappings. I think remaining mutually exclusive between AnonHugePages > 0 and MMUPageSize >4k is actually cleaner than a two liner magic returning 2m if AnonHugePages == Anonymous. -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>