mm: swap: mTHP allocate swap entries from nonfull list

Track the nonfull cluster as well as the empty cluster on lists.  Each
order has one nonfull cluster list.

The cluster will remember which order it was used during new cluster
allocation.

When the cluster has free entry, add to the nonfull[order] list.   When
the free cluster list is empty, also allocate from the nonempty list of
that order.

This improves the mTHP swap allocation success rate.

There are limitations if the distribution of numbers of different orders
of mTHP changes a lot.  e.g.  there are a lot of nonfull cluster assign to
order A while later time there are a lot of order B allocation while very
little allocation in order A.  Currently the cluster used by order A will
not reused by order B unless the cluster is 100% empty.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Chris Li <[email protected]>
Reported-by: Barry Song <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Kairui Song <[email protected]>
Cc: Kalesh Singh <[email protected]>
Cc: Ryan Roberts <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions