On Wed, Sep 22, 2021 at 02:27:24PM +0000, 解 咏梅 wrote: > But now, move_pages_to_lru didn't increase nonresident age for active rotation. > Back toinactive age, VM ONLY care about the pages left inactive lru, AKA activation and reclaiming. > Anyway reactivation is rare case, so whatever it contributes to nonresident age or not is ok to me. > > But I am interested the logic how to guess the pages will be referenced again in the future. > If active reactivation does matter to nonresident age. why not active rotation? But, currently it doesn't. Can you point me to the code you're referring to? Looking at move_pages_to_lru(), any pages with PageActive() set count toward the non-resident age. That means activations from the inactive list, as well as rotations on the active list, increase the nonresident age. As to your question which one is right: the original workingset patch was wrong not to count activations and reactivations. If we see a page referenced in memory, it means it's hotter than the page that's not refaulting -> nonresident age increses. So the code as it is now looks correct to me. Thanks
