Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH 1/5] mm, page_alloc: Spread allocations across zones before introducing fragmentation | From | Vlastimil Babka <> | Date | Mon, 26 Nov 2018 13:36:57 +0100 |
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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@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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