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| author | Baolin Wang <baolin.wang@linux.alibaba.com> | 2022-01-15 01:08:46 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-01-15 17:30:31 +0300 |
| commit | 7813a1b5257b8eb2cb915cd08e7ba857070fdfd3 (patch) | |
| tree | 99ed8f321920321f356b74d55f83688444dda6d2 /mm | |
| parent | ac16ec835314677dd7405dfb5a5e007c3ca424c7 (diff) | |
| download | linux-7813a1b5257b8eb2cb915cd08e7ba857070fdfd3.tar.xz | |
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 <baolin.wang@linux.alibaba.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
Cc: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -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; |