diff options
| author | Baolin Wang <[email protected]> | 2022-01-14 14:08:46 -0800 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2022-01-15 16:30:31 +0200 |
| commit | 7813a1b5257b8eb2cb915cd08e7ba857070fdfd3 (patch) | |
| tree | 99ed8f321920321f356b74d55f83688444dda6d2 | |
| parent | ac16ec835314677dd7405dfb5a5e007c3ca424c7 (diff) | |
mm: migrate: add more comments for selecting target node randomly
As Yang Shi suggested [1], it will be helpful to explain why we should
select target node randomly now if there are multiple target nodes.
[1] https://lore.kernel.org/all/CAHbLzkqSqCL+g7dfzeOw8fPyeEC0BBv13Ny1UVGHDkadnQdR=g@mail.gmail.com/
Link: https://lkml.kernel.org/r/c31d36bd097c6e9e69fc0f409c43b78e53e64fc2.1637766801.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: zhongjiang-ali <[email protected]>
Cc: Xunlei Pang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | mm/migrate.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 9d2642a34018..f50087d3ebf2 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1206,6 +1206,14 @@ int next_demotion_node(int node) /* * If there are multiple target nodes, just select one * target node randomly. + * + * In addition, we can also use round-robin to select + * target node, but we should introduce another variable + * for node_demotion[] to record last selected target node, + * that may cause cache ping-pong due to the changing of + * last target node. Or introducing per-cpu data to avoid + * caching issue, which seems more complicated. So selecting + * target node randomly seems better until now. */ index = get_random_int() % target_nr; break; |