Re: [PATCH v2 4/4] mm, compaction: direct freepage allocation for async direct compaction
From: Vlastimil Babka
Date: Mon Apr 11 2016 - 03:27:11 EST
On 04/11/2016 09:13 AM, Joonsoo Kim wrote:
On Thu, Mar 31, 2016 at 10:50:36AM +0200, Vlastimil Babka wrote:
The goal of direct compaction is to quickly make a high-order page available
for the pending allocation. The free page scanner can add significant latency
when searching for migration targets, although to succeed the compaction, the
only important limit on the target free pages is that they must not come from
the same order-aligned block as the migrated pages.
If we fails migration, free pages will remain and they can interfere
further compaction success because they doesn't come from previous
order-aligned block but can come from next order-aligned block. You
need to free remaining freelist after migration attempt fails?
Oh, good point, thanks!