hi,
Why?
Returning ISOLATE_SUCCESS means that we fall through. This means busy
work in migrate_pages(), updating list accounting and the list. It's
wasteful but is it functionally incorrect? What problem did you observe?
there may are many times the cc->migratepages is zero, but the return
value is ISOLATE_SUCCESS.
If this is simply a performance issue then minimally COMPACTBLOCKS
yes, My concern is the performance.
the comment of ISOLATE_NONE makes me confused. :(
If you think we should update the COMPACTBLOCK in this case, my patch is
wrong.
still needs to be updated, we still want to see the tracepoint etc. To
ok.
preserve that, I would suggest as an alternative to leave it returning
ISOLATE_SUCCESS but move
err = migrate_pages(&cc->migratepages, compaction_alloc,
(unsigned long)cc, false,
cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC);
update_nr_listpages(cc);
inside a if (nr_migrate) check to avoid some overhead.
thanks.
Huang Shijie
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