On 11/23/18 12:45 PM, Mel Gorman wrote: ... > Fault latencies are slightly reduced while allocation success rates remain > at zero as this configuration does not make any special effort to allocate > THP and fio is heavily active at the time and either filling memory or > keeping pages resident. However, a 49% reduction of serious fragmentation > events reduces the changes of external fragmentation being a problem in > the future. > > Vlastimil asked during review for a breakdown of the allocation types > that are falling back. > > vanilla > 3816 MIGRATE_UNMOVABLE > 800845 MIGRATE_MOVABLE > 33 MIGRATE_UNRECLAIMABLE > > patch > 735 MIGRATE_UNMOVABLE > 408135 MIGRATE_MOVABLE > 42 MIGRATE_UNRECLAIMABLE Nit: it's MIGRATE_RECLAIMABLE :) > The majority of the fallbacks are due to movable allocations and this is > consistent for the workload throughout the series so will not be presented > again as the primary source of fallbacks are movable allocations. Note that I was more interested in the *reduction* of different kinds of fallbacks, not their ratios - that the majority is caused by movable allocations is fully expected. And the results above actually show that while the reduction for MOVABLE is ~50%, the reduction for UNMOVABLE is actually 80%! IMHO that's great (better than I would expect, in fact), and good to know. ... > Overall, the patch reduces the number of external fragmentation causing > events so the success of THP over long periods of time would be improved > for this adverse workload. > > Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
