* nishimura@xxxxxxxxxxxxxxxxx <nishimura@xxxxxxxxxxxxxxxxx> [2011-03-28 16:33:11]:
> Hi,
>
> This patch looks good to me, except for one nitpick.
>
> On Sun, 27 Mar 2011 23:12:54 -0700
> Ying Han <yinghan@xxxxxxxxxx> wrote:
>
> > In the global background reclaim, we do soft reclaim before scanning the
> > per-zone LRU. However, the return value is ignored. This patch adds the logic
> > where no per-zone reclaim happens if the soft reclaim raise the free pages
> > above the zone's high_wmark.
> >
> > I did notice a similar check exists but instead leaving a "gap" above the
> > high_wmark(the code right after my change in vmscan.c). There are discussions
> > on whether or not removing the "gap" which intends to balance pressures across
> > zones over time. Without fully understand the logic behind, I didn't try to
> > merge them into one, but instead adding the condition only for memcg users
> > who care a lot on memory isolation.
> >
> > Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
> > ---
> > mm/vmscan.c | 16 +++++++++++++++-
> > 1 files changed, 15 insertions(+), 1 deletions(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 060e4c1..e4601c5 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -2320,6 +2320,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
> > int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
> > unsigned long total_scanned;
> > struct reclaim_state *reclaim_state = current->reclaim_state;
> > + unsigned long nr_soft_reclaimed;
> > struct scan_control sc = {
> > .gfp_mask = GFP_KERNEL,
> > .may_unmap = 1,
> > @@ -2413,7 +2414,20 @@ loop_again:
> > * Call soft limit reclaim before calling shrink_zone.
> > * For now we ignore the return value
>
> You should remove this comment too.
>
> But, Balbir-san, do you remember why did you ignore the return value here ?
>
We do that since soft limit reclaim cannot help us make a decision
from the return value. balance_gap is recomputed following this
routine. May be it might make sense to increment sc.nr_reclaimed based
on the return value?
--
Three Cheers,
Balbir
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>