On Tue, Sep 27, 2011 at 11:42 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote: > Hi :) > > On Wed, Sep 28, 2011 at 00:14, Prateek Sharma <prateek3.14@xxxxxxxxx> wrote: >> Hello everyone, >> I am trying to understand the kernel page frame reclaiming >> mechanism, but one thing's bothering me: >> How does the kernel 'know' which anonymous pages to evict? In the LRU >> scheme, 'referenced/used' information for each page is required >> (AFAIK). But anonymous pages can be used by user processes 'at any >> time' without the kernel knowing about it. > > Same question hog my mind too so far :) > > The only satisfying self answer I could deduce is: > kernel can't track every access to pages when you do it like e.g mov > %ax,8(%esp). What kernel could track is when you access data via > wrappers. I forgot which ones, but remember some of them are updating > those "referenced" etc flags. Perhaps something like get_pages or > alike. > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > page_referenced_anon is called for anonymous pages by page_referenced. And as far as i could figure out, that uses mmu_notifiers. [calls pmdp_clear_flush_young_notify] Whether every anonymous page access is trapped, or only a few of them, i have not yet figured out. Linux-mm seems to be full of magic! _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
