For multi-gen lru shrink_inactive trace, here are some mistake: First, nr_scanned in evict_folios means all folios which it touched in `get_nr_to_scan`(so not means nr_taken). So, we may get some info from trace like this:
``` kswapd0-89 [000] 64.887613: mm_vmscan_lru_shrink_inactive: nid=0 nr_scanned=64 nr_reclaimed=0 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 nr_ref_keep=0 nr_unmap_fail=0 priority=4 flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC ``` Actually, we don't taken too much folios in shrink. This patch use difference between before sc->nr_scanned and after shrink to replace nr_taken and pass this to shrink_inactive tracing. Second, also like above info, we can't get nr_folios going to where, actually in multi-gen lru shrink, many keep by folio_update_gen when look around or other promote this folio. Third, evict_folios don't gather reclaim_stat info after shrink list, so, dirty\writeback\congested stat will miss, and we can't control LRUVEC_CONGESTED or reclaim_throttle. Patch 1 aim to resolve first and second, patch 2 resolve third. Huan Yang (2): tracing: mm: multigen-lru: fix mglru trace mm: multi-gen lru: fix stat count include/linux/vmstat.h | 2 ++ include/trace/events/vmscan.h | 8 ++++- mm/vmscan.c | 61 ++++++++++++++++++++++++++++++++--- 3 files changed, 65 insertions(+), 6 deletions(-) -- 2.34.1
