On Thu, Apr 04, 2024 at 03:06:25PM +0100, Matthew Wilcox wrote: > On Thu, Apr 04, 2024 at 09:45:58AM -0400, Peter Xu wrote: > > On Thu, Apr 04, 2024 at 01:05:57AM +0100, Matthew Wilcox wrote: > > > if (PageHuge(page)) > > > page = compound_head(page); > > > > I would think PageHead() check would help us to avoid compound_head() on > > heads, which should still be the majority cases iiuc (assuming page->flags > > is already around in the cache anyway). I've no strong opinion though, as > > I can hardly tell a difference in reality. > > compound_head() includes a check for PageHead(). Adding the check just > makes things slower. They check different fields (compound_head, offset 0x8 for the former). Again I'm ok with either way to go and I don't expect measurable difference.. so if you prefer this I'm happy with it too. Andrew, could you help update with Matthew's fixup? The comment is definitely better than what I wrote in all cases. Thanks, -- Peter Xu
