Re: [PATCH] add extra free kbytes tunable

From: Hugh Dickins
Date: Fri Mar 01 2013 - 17:34:39 EST


On Fri, 1 Mar 2013, Simon Jeons wrote:
> On 03/01/2013 05:22 PM, Simon Jeons wrote:
> > On 02/23/2013 01:56 AM, Johannes Weiner wrote:
> > > Mapped file pages have to get scanned twice before they are reclaimed
> > > because we don't have enough usage information after the first scan.
> >
> > It seems that just VM_EXEC mapped file pages are protected.
> > Issue in page reclaim subsystem:
> > static inline int page_is_file_cache(struct page *page)
> > {
> > return !PageSwapBacked(page);
> > }
> > AFAIK, PG_swapbacked is set if anonymous page added to swap cache, and be
> > cleaned if removed from swap cache. So anonymous pages which are reclaimed
> > and add to swap cache won't have this flag, then they will be treated as
>
> s/are/aren't

PG_swapbacked != PG_swapcache
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