Re: [PATCH 3/3] Provide control over unmapped pages

Balbir Singh
2010-12-01T05:23:12Z

* Balbir Singh <balbir@linux.vnet.ibm.com> [2010-12-01 10:48:16]:

> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2010-12-01 10:32:54]:
>
> > On Tue, 30 Nov 2010 15:46:31 +0530
> > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> >
> > > Provide control using zone_reclaim() and a boot parameter. The
> > > code reuses functionality from zone_reclaim() to isolate unmapped
> > > pages and reclaim them as a priority, ahead of other mapped pages.
> > >
> > > Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> > > ---
> > > include/linux/swap.h | 5 ++-
> > > mm/page_alloc.c | 7 +++--
> > > mm/vmscan.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-
> > > 3 files changed, 79 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/include/linux/swap.h b/include/linux/swap.h
> > > index eba53e7..78b0830 100644
> > > --- a/include/linux/swap.h
> > > +++ b/include/linux/swap.h
> > > @@ -252,11 +252,12 @@ extern int vm_swappiness;
> > > extern int remove_mapping(struct address_space *mapping, struct page *page);
> > > extern long vm_total_pages;
> > >
> > > -#ifdef CONFIG_NUMA
> > > -extern int zone_reclaim_mode;
> > > extern int sysctl_min_unmapped_ratio;
> > > extern int sysctl_min_slab_ratio;
> > > extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
> > > +extern bool should_balance_unmapped_pages(struct zone *zone);
> > > +#ifdef CONFIG_NUMA
> > > +extern int zone_reclaim_mode;
> > > #else
> > > #define zone_reclaim_mode 0
> > > static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
> > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > > index 62b7280..4228da3 100644
> > > --- a/mm/page_alloc.c
> > > +++ b/mm/page_alloc.c
> > > @@ -1662,6 +1662,9 @@ zonelist_scan:
> > > unsigned long mark;
> > > int ret;
> > >
> > > + if (should_balance_unmapped_pages(zone))
> > > + wakeup_kswapd(zone, order);
> > > +
> >
> > Hm, I'm not sure the final vision of this feature. Does this reclaiming feature
> > can't be called directly via balloon driver just before alloc_page() ?
> >
>
> That is a separate patch, this is a boot paramter based control
> approach.
>
> > Do you need to keep page caches small even when there are free memory on host ?
> >
>
> The goal is to avoid duplication, as you know page cache fills itself
> to consume as much memory as possible. The host generally does not
> have a lot of free memory in a consolidated environment.
>
My local MTA failed to deliver the message, trying again.

--
Three Cheers,
Balbir