Sorry for the delay. Recently I have no time at all ;)
> On Mon, Nov 15, 2010 at 09:50:36AM +0900, KOSAKI Motohiro wrote:
> > > > @@ -1835,8 +1978,6 @@ static void shrink_zone(int priority, st
> > > > break;
> > > > }
> > > >
> > > > - sc->nr_reclaimed = nr_reclaimed;
> > > > -
> > > > /*
> > > > * Even if we did not try to evict anon pages at all, we want to
> > > > * rebalance the anon lru active/inactive ratio.
> > > > @@ -1844,6 +1985,23 @@ static void shrink_zone(int priority, st
> > > > if (inactive_anon_is_low(zone, sc))
> > > > shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
> > > >
> > > > + /*
> > > > + * Don't shrink slabs when reclaiming memory from
> > > > + * over limit cgroups
> > > > + */
> > > > + if (sc->may_reclaim_slab) {
> > > > + struct reclaim_state *reclaim_state = current->reclaim_state;
> > > > +
> > > > + shrink_slab(zone, sc->nr_scanned - nr_scanned,
> > >
> > > Doubtful calculation. What mean "sc->nr_scanned - nr_scanned"?
> > > I think nr_scanned simply keep old slab balancing behavior.
> >
> > And per-zone reclaim can lead to new issue. On 32bit highmem system,
> > theorically the system has following memory usage.
> >
> > ZONE_HIGHMEM: 100% used for page cache
> > ZONE_NORMAL: 100% used for slab
> >
> > So, traditional page-cache/slab balancing may not work. I think following
>
> Yes, in theory you are right. I guess in theory the same hole exists
> if we have 0% page cache reclaimable globally, but this may be slightly
> more likely to hit.
I'm not worry about so much "0% page cache reclaimable globally" case
because I doubt it can be happen in real.
> > new calculation or somethinhg else is necessary.
> >
> > if (zone_reclaimable_pages() > NR_SLAB_RECLAIMABLE) {
> > using current calculation
> > } else {
> > shrink number of "objects >> reclaim-priority" objects
> > (as page cache scanning calculation)
> > }
> >
> > However, it can be separate this patch, perhaps.
>
> I agree. In fact, perhaps the new calculation would work well in all
> cases anyway, so maybe we should move away from making slab reclaim a
> slave to pagecache reclaim.
>
> Can we approach that in subsequent patches?
OK!
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