Johannes Weiner <hannes@xxxxxxxxxxx> writes: > On Tue, Apr 25, 2023 at 11:12:28AM +0800, Huang, Ying wrote: >> Johannes Weiner <hannes@xxxxxxxxxxx> writes: >> >> > Kswapd currently bails on higher-order allocations with an open-coded >> > check for whether it's reclaimed the compaction gap. >> > >> > compaction_suitable() is the customary interface to coordinate reclaim >> > with compaction. >> > >> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> >> > --- >> > mm/vmscan.c | 67 ++++++++++++++++++----------------------------------- >> > 1 file changed, 23 insertions(+), 44 deletions(-) >> > >> > diff --git a/mm/vmscan.c b/mm/vmscan.c >> > index ee8c8ca2e7b5..723705b9e4d9 100644 >> > --- a/mm/vmscan.c >> > +++ b/mm/vmscan.c >> > @@ -6872,12 +6872,18 @@ static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx) >> > if (!managed_zone(zone)) >> > continue; >> > >> > + /* Allocation can succeed in any zone, done */ >> > if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) >> > mark = wmark_pages(zone, WMARK_PROMO); >> > else >> > mark = high_wmark_pages(zone); >> > if (zone_watermark_ok_safe(zone, order, mark, highest_zoneidx)) >> > return true; >> > + >> > + /* Allocation can't succeed, but enough order-0 to compact */ >> > + if (compaction_suitable(zone, order, >> > + highest_zoneidx) == COMPACT_CONTINUE) >> > + return true; >> >> Should we check the following first? >> >> order > 0 && zone_watermark_ok_safe(zone, 0, mark, highest_zoneidx) > > That's what compaction_suitable() does. It checks whether there are > enough migration targets for compaction (COMPACT_CONTINUE) or whether > reclaim needs to do some more work (COMPACT_SKIPPED). Yes. And I found that the watermark used in compaction_suitable() is low_wmark_pages() or min_wmark_pages(), which doesn't match the watermark here. Or did I miss something? Best Regards, Huang, Ying
