On Wed, Jun 15, 2016 at 03:13:13PM +0200, Vlastimil Babka wrote: > On 06/09/2016 08:04 PM, Mel Gorman wrote: > >kswapd checks all eligible zones to see if they need balancing even if it was > >woken for a lower zone. This made sense when we reclaimed on a per-zone basis > >because we wanted to shrink zones fairly so avoid age-inversion problems. > > Now we reclaim a single lru, but still will skip over pages from the higher > zones than reclaim_idx, so this is not much different from per-zone basis > wrt age-inversion? >
Yes, but it only applies in the case where the allocation request is zone restricted. Previously, even with fair zone allocation policy, we had problems with a high zone with recently allocated pages being reclaimed simply because the low watermark was reached. Think of bugs in the past where the normal zone was a small percentage of memory. -- Mel Gorman SUSE Labs
