[Devel] Re: [PATCH 8/8] Per-container pages reclamation

[Andrew Morton]

On Fri, 01 Jun 2007 11:44:25 +0400 Pavel Emelianov <xemul at openvz.org> wrote:

> Andrew Morton wrote:
> > On Thu, 31 May 2007 14:35:43 +0400
> > Pavel Emelianov <xemul at openvz.org> wrote:
> > 
> >>> Would I be correct in guessing that pages which are on the
> >>> per-rss-container lists are also eligible for reclaim off the traditional
> >>> page LRUs?  If so, how does that work?  When a page gets freed off the
> >> Yes. All the pages are accessible from booth - global and per-container
> >> LRU lists and reclamation can be performed from booth.
> >>
> >>> per-zone LRUs does it also get removed from the per-rss_container LRU?  But
> >>> how can this be right?  
> >> I don't get your idea here.
> > 
> > If we have a page which is on the zone LRU with refcount=1 and someone does
> > put_page() on it, we will take that page off the zone LRU and then actually
> > free the page.
> > 
> > I am assuming that your patches change that logic so that we will also
> > remove that page from the per-container LRU at the same time?
> 
> Oh, I see. No that will work another way. Page stays in per-container
> LRU lists as long as it is mapped. When the last process is unmapping
> the page, it it is removed, but stays in global LRU till its refcount
> drops to 0.

ho hum, OK.  This wasn't obvious from the code and it isn't something
I should have learned by emailing you guys!  Please have a think about
preparing an overall decription of the design and implementation of this
rather important kernel change?