Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise

[Michal Hocko]

On Fri 29-01-16 19:35:18, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > From: Michal Hocko <mhocko@xxxxxxxx>
> > 
> > zone_reclaimable_pages is used in should_reclaim_retry which uses it to
> > calculate the target for the watermark check. This means that precise
> > numbers are important for the correct decision. zone_reclaimable_pages
> > uses zone_page_state which can contain stale data with per-cpu diffs
> > not synced yet (the last vmstat_update might have run 1s in the past).
> > 
> > Use zone_page_state_snapshot in zone_reclaimable_pages instead. None
> > of the current callers is in a hot path where getting the precise value
> > (which involves per-cpu iteration) would cause an unreasonable overhead.
> > 
> > Suggested-by: David Rientjes <rientjes@xxxxxxxxxx>
> > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> > ---
> >  mm/vmscan.c | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> > 
> 
> I didn't know http://lkml.kernel.org/r/20151021130323.GC8805@xxxxxxxxxxxxxx
> was forgotten. Anyway,

OK, that explains why this sounded so familiar. Sorry I comepletely
forgot about it.

> Acked-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

Can I change it to your Signed-off-by?

-- 
Michal Hocko
SUSE Labs